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PEW

User Guide

of 86 PEW User Guide

Document Version 1.5 –07 September 2012

About this document This guide is designed to assist the user in becoming quickly familiar with the capabilities of PEW, its interface

and how the program is used.

It has been produced to the recommendations of British Standard BS7649 – Guide to the design and preparation

of documentation for users of application software.

Trademarks All trademarks acknowledged.

.

Associated PEL Support Services Documents PEW Reference Guide: This document summarises the mathematical theory used by the PEW

program.

Contacting PEL Support Services This program is developed, maintained and supported by PEL Support Services, ABB. We run a Hotline

telephone and email service to answer any queries about PEW.

Please let us have any suggestions on how you feel we could improve PEW. You can contact us by any of the

following routes:

By Telephone: ++44 (0)1925 74 1126

By Fax: ++44 (0)1925 74 1265

By E-mail: [email protected]

By Post: PEL Support Services

ABB Limited.

Daresbury Park

Daresbury

Warrington

Cheshire

WA4 4BT

United Kingdom.

Owner: M. G. Pass, ABB.

Approved By: M. G. Pass, ABB.

Document Version / Issue Date: Version 1.5 –07 September 2012

Software Version PEW 4.2.6

Last Amended Date: 07 September 2012

Last Amended By: J. Galligan, ABB.

Copyright 2000-2012 ABB. All rights reserved.

No part of this publication may be reproduced or transmitted in any form, or by means, electronic,

mechanical, photocopying, recording or otherwise without the prior written permission of ABB.

PEW User Guide of 86


Change history This table records the changes made to each new revision of this document.

Changes to approved issues are indicated by a double revision bar on the outer margin next to the text. This is

an example.

Revision Date Description of change

1.0 18 July 2000 First Approved Issue

1.1 05 Feb 2001 Second Approved Issue comprising the following:

Deleted: Text in Appendix C.1 – Vessel Calibration input data –

End dimensions.

New: Figure 20 and accompanying bullets points below.

New: Appendix sections C.3 to C.5.

1.2 21 March 2001 Third Approved Issue (ABB logo attached).

1.3 10 Oct 2002 Fourth Approved Issue (Industrial IT logo & paragraph added, “Eutech”

removed, Front page modified)

1.4 24 October 2005 Removed Industrial IT logo

1.5 07 September

2012

Added PPDS Calculator section. Properties calculator added to tutorial.

Removed images for Windows functions (calculator and save dialog)



Contents

1. PEW User Guide 7

1.1. Introduction ............................................................................................................................................................. 7 1.1.1. Principle features of PEW .................................................................................................................................. 7

1.2. PEW Calculations ................................................................................................................................................... 7 1.2.1. Fluid Flow .......................................................................................................................................................... 7 1.2.2. Heat Transfer ..................................................................................................................................................... 8 1.2.3. Mixing ................................................................................................................................................................ 9 1.2.4. Equipment .......................................................................................................................................................... 9

1.3. How this guide is structured ................................................................................................................................ 10

2. The PEW User Interface 11

2.1. The PEW start up screen ...................................................................................................................................... 11 2.2. Calculation Type Inputs Forms ........................................................................................................................... 12

2.2.1. Fluid Flow Inputs ............................................................................................................................................. 14 2.2.1.1. Incompressible .......................................................................................................................................... 14 2.2.1.2. Compressible ............................................................................................................................................. 15 2.2.1.3. Gravity Flow ............................................................................................................................................. 17 2.2.1.4. Manifold T-junction .................................................................................................................................. 19 2.2.1.5. Symmetrical T-junction ............................................................................................................................ 20 2.2.1.6. Expansion/Contraction .............................................................................................................................. 20 2.2.1.7. Orifice ....................................................................................................................................................... 22 2.2.1.8. Restrictor ................................................................................................................................................... 24 2.2.1.9. Two Phase Flow ........................................................................................................................................ 26

2.2.2. Heat Transfer Inputs......................................................................................................................................... 28 2.2.2.1. Heat Transfer Coefficients ........................................................................................................................ 28 2.2.2.2. Pipe Heat Loss .......................................................................................................................................... 30 2.2.2.3. Vessel Heat Loss ....................................................................................................................................... 33 2.2.2.4. Batch Heating/Cooling .............................................................................................................................. 36 2.2.2.5. Simple Heat Exchanger ............................................................................................................................. 38 2.2.2.6. Tank Solar Heating ................................................................................................................................... 38 2.2.2.7. Finned Tube .............................................................................................................................................. 39

2.2.3. Mixing Inputs ................................................................................................................................................... 41 2.2.3.1. Vortex Profile ............................................................................................................................................ 41 2.2.3.2. Power Numbers ......................................................................................................................................... 42 2.2.3.3. Speed/Power curves .................................................................................................................................. 42

2.2.4. Equipment Inputs ............................................................................................................................................. 49 2.2.4.1. Vessel Calibration ..................................................................................................................................... 49

2.3. Calculation Type – Fittings Form ........................................................................................................................ 51 2.4. Calculation Types – Results Forms ..................................................................................................................... 53 2.5. Handling Calculation Results............................................................................................................................... 54

2.5.1. Printing Results ................................................................................................................................................ 54 2.5.2. Creating a Graph .............................................................................................................................................. 54 2.5.3. Creating a Summary Table............................................................................................................................... 54

2.6. PEW Menus ........................................................................................................................................................... 55 2.6.1. Project Menu .................................................................................................................................................... 55 2.6.2. Calculation Menu ............................................................................................................................................. 56 2.6.3. Edit Menu......................................................................................................................................................... 56 2.6.4. Summary Menu ................................................................................................................................................ 57 2.6.5. Graph Menu ..................................................................................................................................................... 58 2.6.6. Units Menu....................................................................................................................................................... 59 2.6.7. Tools Menu ...................................................................................................................................................... 60

2.6.7.1. Pipe Inner Diameter Calculator ................................................................................................................. 61 2.6.7.2. Molecular Weight Calculator .................................................................................................................... 62 2.6.7.3. K-value Calculator .................................................................................................................................... 63 2.6.7.4. Pipe Roughness Calculator ....................................................................................................................... 66 2.6.7.5. Calculator .................................................................................................................................................. 66



2.6.7.6. Text Editor ................................................................................................................................................ 66 2.6.7.7. Calculate Physical Properties .................................................................................................................... 67 2.6.7.8. Calculate Physical Property ...................................................................................................................... 68

2.6.8. Window Menu ................................................................................................................................................. 68 2.6.9. Help Menu ....................................................................................................................................................... 68

2.7. The PEW Toolbar ................................................................................................................................................. 69

3. PEW Tutorial 71

3.1. General ................................................................................................................................................................... 71 3.2. Solving the Network .............................................................................................................................................. 71

3.2.1. Starting PEW ................................................................................................................................................... 71 3.2.2. Selecting the Calculation type .......................................................................................................................... 71 3.2.3. Entering pipework and losses data on the Inputs form .................................................................................... 72 3.2.4. Entering data on the Fittings form ................................................................................................................... 72 3.2.5. Calculating fluid properties and process conditions data ................................................................................. 73 3.2.6. Performing the Calculation .............................................................................................................................. 74 3.2.7. Repeating the calculation for other values ....................................................................................................... 75 3.2.8. Plotting the Graph ............................................................................................................................................ 75 3.2.9. Creating a Summary Table............................................................................................................................... 76 3.2.10. Saving a PEW file ...................................................................................................................................... 77

Figures

Figure 1 PEW start up screen ................................................................................................................................................ 11 Figure 2 Inputs section of the Incompressible Flow window ............................................................................................... 13 Figure 3 Fittings section of the In/compressible flow window ............................................................................................. 51 Figure 4 Results section of the Calculation Type window .................................................................................................... 53 Figure 5 Units Form .............................................................................................................................................................. 59 Figure 6 Pipe Inner Diameter Calculator dialog ................................................................................................................... 61 Figure 7 Molecular Weight Calculator dialog....................................................................................................................... 62 Figure 8 Fittings Loss (K-value) Calculator dialog .............................................................................................................. 63 Figure 9 Pipe Roughness Calculator dialog .......................................................................................................................... 66 Figure 10 PPDS Calculator dialog ........................................................................................................................................ 67 Figure 11 Selecting the Calculation type .............................................................................................................................. 71 Figure 12 Inputs section of the Incompressible data Input window ...................................................................................... 73 Figure 13 Fittings section of the Incompressible data Input window ................................................................................... 74 Figure 14 Results section of the Incompressible data Input window .................................................................................... 74 Figure 15 Graph of Pressure drop against Mass flow ........................................................................................................... 75 Figure 16 Summary Table..................................................................................................................................................... 76 Figure 17 Choosing a Fluid Flow Program ........................................................................................................................... 81 Figure 18 Vertical Tank with a Dished and Conical End ...................................................................................................... 82 Figure 19 Inclined Vessel ..................................................................................................................................................... 83

Appendices

Appendix A – In-cell Units Conversion ................................................................................................................................. 79 Appendix B – Choosing a Fluid Flow Program ..................................................................................................................... 80 Appendix C – Vessel Calibration ........................................................................................................................................... 82



1. PEW User Guide

1.1. Introduction

The Process Engineers Workbench (PEW) program processes individual process engineering

calculations. It also allows the user to build up a collection (or project) of calculations which can

then be used to generate summaries and graphs to analyse the results.

All the calculations present at any one time, together with any summaries or graphs which have

been created, comprise the project. Any combination of the various calculation types can be

present in a project and several cases of the same type are allowed.

A project can have any number of calculations, graphs and summaries each having its own sub-

window that can be minimised or maximised.

1.1.1. Principle features of PEW

Fluid flow calculations are for single, unbranched pipes of single diameter.

Compressible flow calculations are available in isothermal and adiabatic modes and are valid

up to approximately 0.3 Ma.

Fluids must be single phase gas or liquid.

PEW is capable of Design calculations as well as the usual Ratings calculations, that is, data

about the piping system such as pipe inner diameter or roughness can be calculated from the

fluid flowrate and pressure drop.

1.2. PEW Calculations

The calculations contained in PEW are for:

Fluid Flow

Heat Transfer

Mixing

Equipment.

These are described in the following sections:

1.2.1. Fluid Flow

The calculations available for Fluid Flow are:

Incompressible Flow Calculates either pressure drop, flowrate, roughness or

diameter, given the other three, for flow of an incompressible

fluid along a pipe of circular cross-section.

Compressible Flow Calculates any of inlet/outlet pressure, mass flowrate, or pipe

diameter for adiabatic or isothermal flow of a compressible

fluid along a circular cross-section pipe.

Gravity Flow Calculates either flowrate or depth of liquor in an inclined,

partly filled pipe or duct or pipe diameter in an inclined pipe.

Manifold and Symmetrical

T junctions

Gives the pressure drop through various types of T-junction in

round pipes. Both manifold flow and symmetrical flow are

considered.

Pressure Drop through Calculates both the perceived pressure drop (the static pressure



Expansion/Contraction drop) and the frictional pressure loss for various types of

expansion and contraction in cylindrical pipes.

It displays the number of velocity heads lost in the fitting.

Orifice Calculation This models an orifice or venturi required to measure the

flowrate of a gas, liquid or steam.

It can calculate any one of orifice diameter, pressure drop and

flowrate given the two. The scope is limited to square-edged

orifice plates with one of:

Corner pressure tappings

D and D/2 pressure tappings

Flange pressure tappings.

Restrictor Orifice This models the flow through restrictor orifices for either

liquid or gas flows. It will calculate any one of flowrate,

pressure drop and orifice diameter given the other two.

Two phase flow This program is designed to evaluate the two phase flow

regime in a pipe as well as the frictional and gravitational

pressure drops and the void fraction.

It is based on the methods outlined in the HTFS handbook

sheets TM1, 2, 4, 6, 12, 13, 14 and 15.

1.2.2. Heat Transfer

The calculations available for Heat Transfer are:

Heat Transfer Coefficient The Heat Transfer Coefficient in Smooth Pipes is calculated.

The pipe may be in any orientation and all flow types, from

laminar to turbulent, are catered for.

Pipe Heat Loss This calculates the heat loss from (or gain to) a lagged pipe.

Vessel Heat Loss This models the heat loss from (or gain to) a flat-topped

cylindrical storage vessel, partly full of liquid, standing on the

ground, or raised above the ground.

The vessel can be lagged or unlagged and the effect of solar

radiation can be considered.

The effect of wind speed, conduction into the ground (where

appropriate) and conduction of heat between the liquid and

vapour space are also modelled.

Simple Heat Exchanger This models the exit temperatures, the duty and log mean

temperature difference for a heat exchanger from the inlet

temperature, flowrates and specific heats, heat transfer area and

overall coefficient.

Tank Solar Heating This models the incident solar radiation to flat-topped

cylindrical tanks.

It calculates the radiant heat at intervals throughout the day, the

peak energy input and the total isolation during the day.

Allowance is made for the effects of latitude, time of year and

cloud cover.



Finned Tube Heat Transfer This calculates the heat transfer coefficient and pressure drop

for the flow of a gas over a bank of finned or plain tubes.

Batch Heating and Cooling

Times

This calculates either the time taken to heat (or cool) a batch to

a target temperature or the temperature reached by a batch in a

given time, given a particular heating/cooling load.

1.2.3. Mixing

The calculations available for Mixing are:

Vortex Profile Vortex Profile in unbaffled vessels calculates the shape of the

vortex produced by agitator in a circular unbaffled vessel. It

applies only to agitators mounted on a vertical shaft at the axis

of the vessel.

The shape is described by the heights of the liquid at the

centre, agitator blade tip and circumference of the vessel.

Table of Power Numbers This is a pair of reference tables of power numbers for various

configurations of agitators in baffled and unbaffled vessels

under fully turbulent conditions.

Speed versus Power This calculation enables the evaluation of either agitator speed

given the power or the power required by an agitator given the

agitator speed.

The program uses fitted data from curves of Power Number as

a function of Reynolds Number and applies correction factors

for „non-standard‟ geometries.

1.2.4. Equipment

The calculations available for Equipment are:

Vessel Calibration This calibrates cylindrical tanks that may have a flat,

ellipsoidal, dished or conical ends independently of one

another.

Dished and conical ends may have a transition knuckle and the

axis of the tank may be horizontal, vertical or inclined.



1.3. How this guide is structured

This guide is designed to assist the user in becoming quickly familiar with the capabilities of

PEW, its interface and how the program is used.

The chapters are organised as follows:

Chapter 1 An introduction to PEW.

Chapter 2 Detailed information on the PEW user interface.

Chapter 3 A tutorial to guide the user through a typical PEW session emphasising the

commonly used features. It is recommended that the user should read this

chapter while running the program.

Appendices Describe the In-cell units conversion feature, advice on choosing a Fluid

Flow program and Vessel Calibration.



2. The PEW User Interface

The user interface displays menus and a toolbar that allows the system being modelled to be easily

defined. It also offers many useful features including automatic units conversion and a calculator.

As a general concept, the PEW interface for a calculation consists of an input section on the left of

the screen and a results section on the right. The layout is designed to allow both the inputs and

results to be displayed on a single screen and to be printed on a single sheet of A4 paper.

On-line help is available within the program.

2.1. The PEW start up screen

The PEW start up screen consists of the following:

Menus Bar Displays the menu options that are available.

Toolbar Buttons Descriptive text appears automatically as the cursor is held over the

buttons to describe their function.

Status Bar Displays the upper and lower limits of the information that can be

entered when the cursor is placed in an input cell.

Calculation Type

selection dialog

The first action to take when the PEW start up screen appears is to

select the type of calculation to work on (see section 2.2 for more

information).

Figure 1 PEW start up screen

The following sections in this chapter contain detailed information on how this interface is used.



2.2. Calculation Type Inputs Forms

The first step when using PEW is to select the type of calculation to work on.

The calculation types are accessed by selecting Add from the „Calculation‟ menu or clicking the

Add a new case button (see left) on the toolbar.

The Calculation types available are:

Fluid flow

Heat transfer

Mixing

Equipment.

The selections available from these Calculation types are:

Fluid flow Incompressible

Compressible

Gravity flow

Manifold T-junction

Symmetrical T-junction

Expansion/contraction

Orifice

Restrictor

Two phase flow.

Heat transfer Heat transfer coefficients

Pipe heat loss

Vessel heat loss

Batch heating/cooling

Simple heat exchanger

Tank solar heating

Finned tube.

Mixing Vortex profile

Power numbers

Speed/power curves.

Equipment Vessel calibration.

Selecting a calculation type brings up the appropriate form for that calculation. The form includes

both the input data and results for that calculation.

The details of the input portion of the forms are described further in this chapter.



The example Input form shown in Figure 2 appears when Fluid flow and Incompressible are

selected.

Clicking the Edit . . . button toggles between the Inputs section at the top of the „Incompressible

Flow‟ window and the Fittings section at the bottom of the window.

Figure 2 Inputs section of the Incompressible Flow window

Note. Although the units are displayed in metric, the values can be entered in any units – see

Appendix A for more information. The default units can be changed from metric to any

other required unit set – see section 2.6.6 for more information.

The inputs forms are always populated with reasonable default values as a guide to the

type of information required.

Clicking an input cell displays (on the status bar at the bottom of the screen) the upper

and lower limits of the information that can be entered.



2.2.1. Fluid Flow Inputs

The following are the different types of calculation available for Fluid Flow:

Incompressible

Compressible

Gravity Flow

Manifold T-junction

Symmetrical T-junction

Expansion/Contraction

Orifice

Restrictor

Two Phase Flow.

2.2.1.1. Incompressible

Calculates the incompressible flow along a single, unbranched, cylindrical pipe of a fixed

diameter.

The following selections can be made:

Calculate Select Calculate from one of the following:

Flow

Diameter

Roughness

Pressure Drop (default selection).

Values for the other three must be supplied and the text „(estimated)‟

appears next to the value which is to be calculated.

Pipework Enter values for:

Length

The actual length of the pipe.

Diameter

The internal pipe diameter (see section 2.6.7.1 for more information).

Lining thickness

If there is a lining to the pipe, enter that here.

Roughness

The absolute roughness in the pipe.

The value depends on the material of construction and condition of

the pipe (see section 2.6.7.4 for more information).

Losses Enter values for:

Static head loss

This is the difference in elevation between the point of discharge and

the point of entry to the pipe. Therefore, this number is positive if the

pipe runs uphill and negative if it runs downhill.

Fittings loss (velocity heads)

This is the total K-value for the pipe and should take into account

pipe entry and exit effects, fittings losses, bends, Tee's etc.

The „Edit‟ button displays a form which describes the pipe fittings

which comprise the fittings loss.



Fluid Properties Enter values for:

Density

The actual density of the fluid at operating conditions.

Viscosity

The actual viscosity of the fluid at operating conditions.

Process Conditions Enter values for:

Pressure drop (estimated)

The measured or estimated pressure drop down the pipe is needed.

The program does not cater for reverse flow conditions so the

pressure drop must not be less than the static head loss. If this data is

real, there may be plant data errors (static head errors ), instrument

errors or gas entrainment.

Mass flow

The flowrate down the pipe (default value is kg/s).

2.2.1.2. Compressible

Calculates the compressible flow along a single, unbranched, cylindrical pipe of a fixed diameter.


Flow mode Select Flow mode from either:

Isothermal

The isothermal theory is most suitable when pressure and velocity

changes along the pipe are small relative to the pressure and velocity

of the fluid.

Adiabatic

For higher Mach numbers, adiabatic theory is normally preferred as

smaller errors are likely than for other conditions.


Flow

Diameter

Inlet Pressure

Outlet Pressure (this is the default selection).

Values for the other three must be supplied and the text „(estimated)‟

appears next to the value which is to be calculated.


Length

The actual length of the pipe.

Diameter

The internal pipe diameter (see section 2.6.7.1 for more information).

Lining thickness

The pipe lining thickness (if applicable).

Roughness

The absolute roughness in the pipe.

The value depends on the material of construction and condition of

the pipe (see section 2.6.7.4 for more information).

Fittings loss (velocity heads)



This is the total K-value for the pipe and should take into account

pipe entry and exit effects, fittings losses, bends, Tee's etc.

The „Edit‟ button displays a form which describes the pipe fittings

which comprise the fittings loss.

Fluid properties Enter values for:

Density at 0 C and 1 bara

The density should be given at C and 1 bara as the calculation uses

ideal gas theory to calculate the densities at operating conditions from

this value.

Viscosity (process conditions)

The viscosity at mean operating conditions is needed. This implies

that some idea of the answers is needed before running the program.

For example, the viscosity of steam is approximately 0.02 cP.

Gamma

The ratio of specific heats, gamma or Cp/Cv is required for any

compressible flow calculations.

Process conditions Enter values for:

Inlet / Outlet pressure

Either the measured or the target value is required for each of these.

The program will reject the input if the outlet pressure is greater than

the inlet pressure.

Inlet temperature

The inlet temperature is needed to calculate the actual density and,

for adiabatic flow, the temperature loss.

Mass flow

The mass flowrate down the pipe is required.

A volume flowrate cannot be used as any of the conditions inputs

could affect the actual mass flowrate.



2.2.1.3. Gravity Flow

Calculates the gravity flow in an inclined, partially filled pipe or duct.


Container type Select Container type from either:

Pipe (a closed vessel)

Duct (an open vessel).


Flowrate

The mass flowrate in the container.

Depth

The depth of the fluid in the container.

Diameter (pipe only)

The diameter of the pipe.

Dimensions Enter values for:

Lining thickness

Enter a value of 0.0 if the pipe or duct is unlined or the lining

thickness has been included in the diameter.

A typical epoxy or ebonite lining has a thickness of 6 mm.

Roughness of wall

The absolute roughness in the pipe and the condition of the pipe.

Slope

A positive fraction is required.

A slope of 0.025 (1:40) is recommended as any larger will lead to

wave formation. Smaller slopes are more difficult to install though

slopes of 0.005 (1:200) are commonly found in chlorine cellroom

headers.


Density and Viscosity of the fluid at operating conditions.

Pipe conditions Different inputs are required depending on the calculated variable

and whether the container is a pipe or a duct.

The required inputs are:

Container Type

Calculated Variable Pipe Duct

Flowrate Pipe Diameter

Relative Depth

Duct Width

Liquor Level

Depth Pipe Diameter

Liquor Flowrate

Duct Width

Liquor Flowrate

Diameter Maximum Relative Depth

Liquor Flowrate

N/A



When the container is a Pipe:

Calculate Flowrate

This is the mass flowrate. The following inputs are required:

Pipe Diameter

This is the actual inner diameter as the lining thickness is

subtracted if the lining is present.

Relative Depth

The observed relative diameter is required, that is, the observed

depth of liquid/pipe diameter.

Calculate Depth

The observed relative diameter is required, that is, the observed depth

of liquid/pipe diameter. Values above 0.8 can mean that the

maximum stable flow limitation is being reached.

The following inputs are required:

Pipe Diameter

This is the actual inner diameter as the lining thickness is

subtracted if the lining is present.

Liquor Flowrate

The actual mass flowrate.

Calculate Diameter

The program calculates internal diameters for pipes assuming it to be

an ANSI 150 standard carbon steel pipe as follows:

1 – 1+ in Schedule 80

2 – 6 in Schedule 40

8 – 16 in Schedule 30

18 in Schedule Wall

20, 24 in Schedule 80

Above 24 in Metric sizes.

The result will be the actual inner diameter seen by the flowing liquor

as the lining thickness is subtracted if the lining is present.

The following inputs are required.

Maximum Relative Depth

The maximum relative depth allowable before a larger pipe size

is required. Values above 0.8 can mean that the maximum stable

flow limitation is being reached.

Liquor Flowrate


When the container is a Duct:

Calculate Flowrate

This is the mass flowrate. The following inputs are required:

Duct Width

The duct width. The program subtracts the lining thickness if one

has been specified.

Liquor Level

The fluid level in the duct.



Calculate Depth

This is the fluid level in the duct. The following inputs are required:

Duct Width

The duct width. The program subtracts the lining thickness if one

has been specified.

Liquor Flowrate


2.2.1.4. Manifold T-junction

Calculates the pressure drop for a T-junction consisting of a straight manifold of consistent bore

with a (smaller) branch pipe at right angles to it. Both combining and dividing flows are possible.


Flow Select Flow type from one of the following:

Combining

Dividing.

Enter values for:

Mass flow into/out of manifold

The mass flow into the T along the manifold and the mass flow away

from the T along the manifold are required.

Mass flow in branch

PEW calculates the branch flow from the mass flow into the manifold

and the mass flow out of the manifold. If the two known flowrates

include the branch flow, the calculator can be used to calculate the

missing manifold flow.


Manifold diameter

This is the diameter of the main pipe. Note this is assumed to be

straight with the branch at right angles.

Branch diameter

This is the diameter of the branch. This must not be greater than the

manifold diameter.

The branch-manifold join is assumed to be sharp-edged with no

rounding


Density manifold in/out

The density of the fluid in the inlet and outlet manifolds should be

supplied at the operating conditions.

Density in branch

The density of the fluid in the branch at the operating conditions is

also required.

Note. These correlations are for single phase flow only.

Viscosity

This is only required to check the Reynolds Number. If in doubt,

make it too large rather than too small.



2.2.1.5. Symmetrical T-junction

Calculates the pressure drop in T-junctions consisting of a straight manifold of constant bore with

a branch pipe of the same bore at right angles to it. The junction should have a sharp-edged join

with all the flow entering or leaving via the branch.

They are of two types of T-junction: Combining or Dividing.

Flow is symmetrical about the branch either entering or leaving through both arms of the T.


Flows Select Flows from one of the following:

Combining

Dividing.

Pipe diameters The T-junction is symmetrical so the branch and the main part of the

T-junction are assumed to have the same diameter.


Inlet / Outlet density

The density of the inlet and outlet fluid should be given at the

operating conditions.

Note. These correlations are for single phase flow only.

Viscosity



2.2.1.6. Expansion/Contraction

Calculates both the perceived pressure drop (the static pressure drop) and the frictional pressure

loss for various types of expansion and contraction in cylindrical pipes.


Pipe diameter Enter Pipe diameter values for:

Inlet

The diameter of the upstream pipe.

Outlet

The diameter of the downstream pipe.

PEW compares the two diameters to determine whether a contraction

or expansion is being specified and sets the shape options for the

fitting accordingly.

Included angle of

expansion

Specify the following if an expansion is detected:

Conical Expansion types

Data is available for various angles of the cone. These are:

0 to 15

15 to 25

25 to 35

35 to 50

50 to 120



Abrupt Expansion types

An immediate right-angle (180) change in diameter.

Contraction type

If a contraction is detected, specify the following:

Rounded

A smoothly rounded change in diameter.

Tapered

Data used here assumes a cone of total angle ≤ 60 degrees.

Abrupt

An immediate right angle change in diameter.


Mass flow

The mass flow through the fitting.

Inlet density

The inlet density of the fluid in the pipe at the entry to the fitting.

Outlet density

The outlet density of the fluid in the pipe at the exit from the fitting.

Viscosity





2.2.1.7. Orifice

Models an orifice or venturi required to measure the flowrate of a gas, liquid or steam. It can

calculate one of orifice diameter, pressure drop and flowrate given the other two. The scope is

limited to square-edged orifice plates with one of the following:

Corner pressure tapping

D and D/2 pressure tappings

Flange pressure tappings.


General data Select the variable to calculate from one of the following:

Flow

Pressure drop

Orifice diameter.

Select the Fluid from the following:

Liquid

Gas

Steam.

The remaining information required in the „General Data‟ section is

dependant on the choices made for the Fluid and the required

variable to Calculate.

The required inputs are:

Fluid Type

Calculated

Variable Liquid Gas Steam

Flow Density Density

Gamma

Gamma

Pressure

Drop

Density

Flow Meter Range

Density

Gamma

Flow Meter

Range

Gamma

Flow Meter

Range

Orifice

Diameter

Density

Flow Meter Range

Density

Gamma

Flow Meter

Range

Gamma

Flow Meter

Range

The various inputs are:

Density

Give a reference fluid density at 20 C and 1 atmosphere.

Gamma

The ratio of specific heats is required for gas or steam – typically

around 1.4.



Flow Meter Range

The maximum flow allowed on the flow meter is required, unless this

is the calculated variable. If a pre-existing orifice plate is being rated,

it is the flow that is used to calculate the pressure drop.

Upstream physical

properties

Enter values for:

Pressure

The pressure upstream of the orifice plate.

Temperature

The temperature upstream of the orifice.

Density

The density upstream of the orifice.

Viscosity

The viscosity upstream of the orifice.

Orifice details The calculated variable chosen earlier determines the values to be

entered here:

Calculated variable – Flow

Inputs are required for:

Orifice diameter

Orifice pressure drop

Calculated variable – Pressure Drop


Orifice diameter

Calculated variable – Orifice diameter


Standard Orifice (Y/N)

If a standard orifice size is to be found, the program assumes the

given maximum flow and uses the closest pressure drop to that

given.

Orifice pressure drop

Class B (Y/N)

Is a class B calculation required? If No then the pipe condition and a

% correction must be supplied.

The Pipe category should be selected from one of the following:

1. Steel non-rusty cold-drawn

2. Steel non-rusty seamless

3. Steel non-rusty welded

4. Steel slightly rusty

5. Steel rusty

6. Steel slightly over-rusted

7. Steel new bitumenised

8. Steel used bitumenised

9. Steel galvanised

10. Cast iron non-rusty

11. Cast iron rusty

12. Cast iron bitumenised.



Correction Factor

The percentage of pressure drop for expansibility, Re and correction

factors. Typical value is 50%.

Select Taps from one of the following:

Corner

D and D/2

Flanged

Venturi

Tolerances

This is only appropriate when the upstream and downstream straight

pipe lengths are less than the minimum.

Leave as zero unless there is a special reason.

Corrections

Leave as zero unless there is a special reason.

Material

Select the pipe Material from one of the following:

MS (Mild Steel)

SS (Stainless Steel)

CI (Cast Iron)

Other (any other).

Pipe internal diameter

Enter the actual internal diameter of the pipe.

2.2.1.8. Restrictor

This program models the flow through restrictor orifices for either liquid or gas flows. It calculates

any one of flowrate, pressure drop and orifice diameter given the other two.



Flow

Pressure drop

Orifice diameter

For gases: this should be less than 13% of the pipe area. If it is

much greater than this, the experimental results on which the

calculations are based do not apply and theoretical extrapolation

may be suspect.

For liquids: the relevant ratio is Orifice thickness/diameter (t/d).

If this is between 0.6 and 1.0 it is not possible to predict whether

the flow reattaches before leaving the orifice, and this affects the

pressure drop. The calculation assumes 0.8 as the dividing line

but displays a warning.

Geometry Enter values for:

Pipe diameter

The internal diameter of the pipe must be given. For gases, the

ratio of orifice diameter to this diameter is important.



Orifice diameter

For gases:

This should be less than 13% of the pipe area.

If it is much greater than this, the experimental results on which

the calculations are based do not apply and theoretical

extrapolation may be suspect.

For liquids:

The relevant ratio is Orifice thickness/diameter (t/d).

If this is between 0.6 and 1.0 it is not possible to predict whether

the flow reattaches before leaving the orifice, and this affects the

pressure drop. The calculation assumes 0.8 as the dividing line,

but gives a warning.

For calculating orifice diameter, the program first assumes

separated flow and, if this indicates uncertainty, calculates for

reattached flow. If the answer is still in the uncertain region then

both values are given together with a warning.

Plate thickness

This is the thickness from the upstream to the downstream side. It

is important for liquid flow (see above).


Upstream/Downstream pressure

If the pressure drop calculation is requested, the downstream

pressure is calculated from the upstream pressure. For gases, the

downstream pressure should not be less than one fifth of the

upstream pressure.

Mass flow

The mass flowrate can be supplied or calculated from orifice

diameter and pressure drop if required.

Upstream temperature

The upstream temperature must be supplied but the program will

calculate the static and stagnation temperatures.

Fluid properties Enter the following values for either Liquid or Gas:

Liquid:

Viscosity

Fluid viscosity. Typical values are around 1 cP for liquids.

Density

Density. An example is Water = 1000 kg/m3.

Gas:

Viscosity

Fluid viscosity. Typical values are around 0.018 cP for air at

ambient conditions.

Compressibility

The Compressibility factor. This represents the deviation from

ideal.

Exponent K

This is the exponent of isentropic expansion, for ideal gases –

this is the same as Gamma.



Molecular weight

See section 2.6.7.2 for more information on the molecular weight

calculator.

Results The results are displayed on screen when the problem is calculated.

If the calculation generates any warnings or errors, these can be

accessed by pressing the „Show details‟ button. A warning message

indicating that more information is available appears in red.

2.2.1.9. Two Phase Flow

This program characterises the two phase flow regime using several different methods. The

frictional and gravitational pressure gradients and the calculated void fraction are also supplied.


Pipe characteristics Enter the following values:

Slope of pipe

The angle of the pipe to the horizontal is required with negative

being defined as down flow. The program has no facility to

handle angled pipes. Therefore, it performs the calculation for

both horizontal and vertical flow then reports the results for both.

Pipe diameter

The internal pipe diameter.

Pipe roughness

See section 2.6.7.4 for more information on the Pipe Roughness

Calculator.

Process fluids Enter the following values for either Liquid or Vapour:

Liquid:

Flowrate (required in mass units).

Density (at the operating conditions).

Typical values are:

Water: 1000 kg/m3

Ethanol: 789 kg/m3

Acetone: 788 kg/m3

Viscosity (at the operating conditions).

Typical values are:

Water: 1.0019 Cp

Ethanol: 1.197 Cp

Benzene: 64.7 Cp.

Liquid Surface Tension (Mandatory)

Typical surface tension values are:

Water: 72 dyn/cm

Methanol: 26 dyn/cm

Benzene: 28 dyn/cm

Mercury: 472 dyn/cm



Vapour:

Flowrate (required in mass units).

Density (at the operating conditions).

Typical values are:

Air: 1.2928 kg/m3

CO2: 1.9768 kg/m3

Ethane: 1.3567 kg/m3

Viscosity (at the operating conditions).

Typical values are:

Air: 0.01812Cp

Ethanol: 0.01463 Cp

Benzene: 0.00915 Cp.



2.2.2. Heat Transfer Inputs

This program calculates coefficients for smooth pipes. The pipe can be in any orientation and all

the different flow regimes from laminar to turbulent are catered for.

The following are the different types of calculation available for Heat Transfer:

Heat Transfer Coefficients

Pipe Heat Loss

Vessel Heat Loss

Batch Heating/Cooling

Simple Heat Exchanger

Tank Solar Heating

Finned Tube.

2.2.2.1. Heat Transfer Coefficients


Flowrates Select Flowrates from one of the following:

Velocity (in m/s)

Enter the mean velocity in the pipe.

Mass (in kg/s)

Enter the mass flowrate in the pipe.

Volume (in m3/s)

Enter the volume flowrate in the pipe.

Pipe properties Enter values for:

Diameter (Internal)

This is assumed to be a smooth pipe, that is, a relative roughness

of below 0.00001.

Length (from inlet)

The length of the tube from the inlet.

Orientation

Enter whether the pipe is horizontal or vertical.

Flow direction

The direction of flow in a vertical pipe is required.

System Temperatures Enter values for:

Wall temperature

The temperature of the wall. If it is not known then it can be

found using an estimation of the tube side coefficient, the wall

resistance and the temperature and heat transfer coefficient of the

fluid outside the tube.

Fluid inlet temperature

The temperature of the bulk fluid at the inlet is required.

Fluid outlet temperature

The outlet temperature of the bulk fluid is required.



Fluid Physical

Properties

Enter the following values for either Liquid or Gas:

Viscosity (Fluid Temp)

Some typical values are (cP ):

25 C 100 C

Water 1.0 0.3

Hydrocarbons 0.4 0.2 ( liquid )

Hydrocarbons 0.008 0.010 ( vapours )

Steam 0.01 0.013

Air 0.018 0.022

Viscosity (Wall Temp)

Some typical values are (cP ):

25 C 100 C

Water 1.0 0.3

Hydrocarbons 0.4 0.2 ( liquid )

Hydrocarbons 0.008 0.010 ( vapours )

Steam 0.01 0.013

Air 0.018 0.022

Density

The density at the bulk fluid temperature is required for

horizontal tubes and at the wall temperature for vertical tubes.

Specific Heat Capacity

The specific heat capacity at the bulk fluid temperature is

required.

Some typical values are ( all J/kg.K ):

Water 4200

Hydrocarbons 2000-3000 (gaseous and liquid)

Steam 2000

Air 1000

Thermal Conductivity

The thermal conductivity is required at the bulk fluid

temperature.

Some typical values are ( all W/m.K ):

25 C 100 C

Water 0.50 0.55

Hydrocarbons 0.1 0.08 (liquid)

Hydrocarbons 0.013 0.02 (vapours)

Steam 0.015 0.021

Air 0.025 0.027

Thermal Expansion Coefficient

The thermal expansion coefficient at the bulk fluid temperature

is required for horizontal tubes and at the wall temperature for

vertical tubes. The thermal expansion coefficient may be

estimated using the difference in densities at two temperatures or

set to 1/T(K) for gases at low pressures.



2.2.2.2. Pipe Heat Loss

Calculates the heat loss (or gain) from a (lagged) pipe either at a single point or as a profile along

the pipe.


Calculation type Select Calculation type from one of the following:

Single point

Profile along pipe.

Geometry Enter values for:

Pipe length

This is not used by the calculation program itself as it displays

the heat loss per metre of pipe. However, when that is returned to

PEW, the total heat loss is calculated using this length. This

assumes constant fluid temperature down the pipe.

Internal diameter

This diameter excludes any lining which may be present.

Wall thickness

The thickness of the wall should be given excluding any lagging

or lining.

Lagging thickness

This can be zero if no lagging is present.

Lining thickness

The lining is assumed to be within the pipe. If no lining is present

then enter zero for this value. The lining thickness is limited to

90% of the pipe radius as it is assumed that at least 10% of the

pipe should remain clear.

Process Select Fluid from either of the following:

Condensing

If the fluid is condensing then it is assumed to be at a constant

temperature along the length of the pipe and the temperature

profile option is not be displayed.

Non-condensing

Enter values for:

Mass Flow

The mass flowrate of fluid through the pipe helps to determine

the inside heat transfer coefficient. Note that the underlying

calculation engine assumes turbulent flow in its calculations.

Internal temperature

This is the average temperature of the fluid within the pipe.

External Temperature

The temperature of the air outside the pipe must lie between

-40°C and 40°C as the properties of air in the program only cover

this range.



Heat transfer Select Inside coefficient from either of the following:

Given

Calculated

Enter values for:

Wall Conductivity (the thermal conductivity of the wall

material).

Some approximate values in W/m.°C are:

Brick 0.4 - 0.8

Hastelloy 9 - 20

Inconel 12 - 14

Stainless 13 - 26

Monel c.25

Carbon Steel 40 - 50

Lagging conductivity

Some typical values (W/m.°C) are:

Nilflame 0.03 @ 100°C

Calcium Silicate 0.055 @ 100°C

0.08 @ 600°C

Lining conductivity

Typical values (W/m.°C) are:

Plastic 0.12 ->1.7

Glass 1 -> 4

Inside dirt resistance

This must lie between 0 and 0.05

Surface emissivity

This determines the heat loss due to radiation.

The background temperature is assumed to be the air

temperature. A figure of 0.9 represents a typically dirty surface.

Inside coefficient

This is the heat transfer coefficient between the fluid in the pipe

and the pipe wall. This can be calculated by the program if it is

not supplied.

The program calculates the inside coefficient given fluid flow,

viscosity and thermal conductivity but turbulent flow is assumed.

If laminar flow is suspected, the coefficient must be estimated

and supplied to the program.

Additionally, if the tube contains a vapour which is condensing

due to the heat loss, the coefficient is much higher than the

calculated single phase values. Note that condensation can occur

on the pipe walls even if the bulk vapour is superheated (wet wall

superheated).

For cases other than single phase turbulent flow the user should

calculate the inside coefficient and input it into the program. In

the absence of a user specified value, the program assumes an

inside coefficient of 10,000 w/m2 for condensing fluids.



Fluid properties Properties for the fluid must be supplied at two temperatures if a

temperature profile is to be calculated.

Enter values for:

Temperatures

Specific heat capacity

Typical specific heats (J/kg.°C) are:

Water approx. 4200

Steam 1900-2100

Organic liquids 840 – 2500

Viscosity

Typical viscosities (cP) are:

Water 0.3 – 1.8

Steam approx. 0.02

Conductivity

Typical conductivities (j/kg.C) are:

Water approx. 0.6

Steam 0.02 – 0.04

Results Basic results are shown on screen in the form of heat loss in W or

W/m versus differing wind speeds.

More detailed results are available by accessing the „Show details‟

button.

For a single point calculation these include for each wind speed:

The temperatures at the interface between fluid, lining, wall,

lagging and air.

The inside heat transfer coefficient and the elements which

comprise the outside heat transfer coefficient.

Natural convection forced, forced convection and radiation.

For a temperature profile case, these values are given at 10

equidistant points along the pipe in addition to the inlet.



2.2.2.3. Vessel Heat Loss

This program models the heat loss from a flat-tipped cylindrical storage vessel partly filled with

liquid, standing on the ground or raised on legs.

The vessel can be lagged or unlagged and the effects of solar radiation can be considered.

The effects of windspeed, conduction into the ground (where appropriate) and conduction of heat

between the liquid and vapour space within the vessel can also modelled.


Tank description The tank is assumed to be a vertical cylinder with a flat roof.

Enter the following Tank description information

Internal diameter

The internal diameter.

Height

The height of the tank.

Wall thickness

The thickness of the tank walls. The roof is assumed to be the

same thickness.

Liquid level %

The liquid level in the tank as a percentage.

Temperature

The temperature of the liquid in the tank. The vapour

temperature is calculated and so is closer to the ambient

temperature than the liquid.

Pressure

The pressure within the tank.

Conductivity

The thermal conductivity of the tank. Some typical approximate

values in W/m.C are:

Brick 0.4 - 0.8

Hastelloy 9 - 20

Inconel 12 - 14

Stainless 13 - 26

Monel 25 (approx.)

Carbon Steel 40 - 50

Location

Select either On Ground or On Legs.

For a tank on legs, the calculation assumes that the vessel is

completely surrounded by air at constant ambient conditions and

the base is assumed to be flat.

See the following section „Ground conditions‟ for more

information.



Lagging Any combination of walls, roof and base of the tank can be lagged.

However, it is assumed that the base of a tank on the ground cannot

be lagged.

Select Lagging from one of the following:

Walls

Roof

Base

Specify the following if any lagging is present:

Thickness

All the lagging is assumed to be the same thickness.

Thermal Conductivity

The lagging thermal conductivity. Typical values are:

Nilflame 0.03 @ 100 C

Calcium Sulphate 0.055 @ 100 C

0.08 @ 600 C

Emissivities Enter a value for:

Tank

The tank emissivity is required if any tank surface is unlagged.

A typical value is 0.9 (This is the tank surface not the lagging

surface).

Lagging

The lagging emissivity is required if any lagging is present.

A typical value is 0.8.

Solar radiation The calculations can be carried out with or without including the

heating effect of the sun on the tank. The effects are assumed to apply

over the entire vessel top and over the projected area of half of the

wetted and unwetted cylinder.

Enter either Yes or No:

Yes:

The program iterates to achieve a balance between heat lost/gained

by the liquid surface, heat lost/gained by the unwetted walls in the

sun and in the shade, and the heat lost/gained by the roof in the sun.

If solar radiation is to be considered, the following information is

required:

Latitude

The latitude (in degrees) north of the equator is needed. A value

of 50 would be typical for the UK.

Solar Energy

The solar energy incident on a horizontal surface.

Values can be calculated for a given set of conditions using the

tank solar heating program in PEW.

No:

Solar radiation is ignored.



Ambient conditions Enter Ambient conditions values for:

Temperature

The ambient temperature outside the tank should be supplied. It

is assumed to be constant all around the tank.

Wind Speed

The wind speed affects the convection from the tank surfaces.

Typical values are:

Gale force 3 to 4 = 5 m/s

Gale force 8 = 15 m/s.

Ground conditions If the tank location is selected as On Ground, enter values for:

Temperature

The ground on which the tank sits is modelled as an infinite flat

solid and heat loss into it is through conduction.

Thermal conductivity

Typical values are around 0.5 W/m2.C

Physical Properties Physical properties for both the liquid and vapour are required.

Liquid in tank The physical properties of the tank liquid at three reference

temperatures are required.

The first two reference temperatures should span the range of

temperatures in the tank and surroundings and are the temperatures

for the following data on density, conductivity and specific heat.

The third reference temperature is only needed to calculate liquid

viscosity which is modelled with an Antoine type equation.

The default property values provided are those of water.

Density

Liquid density at the first two reference temperatures. Note the

second density value must be less than the first, because

otherwise the coefficient of volumetric expansion will be

negative, and the Grashof number, used in the correlations for

htc becomes negative, with strange effects.

Conductivity

Liquid thermal conductivities at the first two reference

temperatures.

Specific heat

Liquid specific heat at the first two reference temperatures.

Viscosity

Liquid viscosity at three temperatures. These must not be

identical or the program will not be able to work out the

constants for the Antoine-like equation that it uses.

Vapour in tank The physical properties of the tank vapour at two reference

temperatures are required. The reference temperatures should span

the range of temperatures in the tank and surroundings.

Is the vapour air?

Enter either Yes or No:

Yes:



The program has built in correlations for the physical properties of air

so vapour properties for air are not required.

The default property values provided are those of air but do not give

exactly the same answers as the internal correlations, as these are

more accurate.

No:

The following values must be supplied if the vapour is not air:

Vapour thermal conductivity at the first two reference

temperatures.

Vapour specific heat at the first two reference temperatures.

Vapour viscosity at the first two reference temperatures.

Vapour molecular weight. The average molecular weight at

operating conditions.

Results The total heat loss for the vessel appears on the screen.

More detailed results are available by pressing the „Show details‟

button.

2.2.2.4. Batch Heating/Cooling

This program calculates either the time taken to heat (or cool) a batch to a target temperature or the

temperature reached by a batch in a given time given a heating/cooling load.

In either case, PEW divides the target to 10 equal time/temperature points to indicate the progress

of the batch to its final state.


Operating Conditions Select Calculate from one of the following:

Duration

The time required to heat up or cool down the batch.

Final Temperature

The final temperature of the batch is calculated given the time

available.

Select Heating Medium from one of the following:

Non-Isothermal

The heat exchange medium is assumed to have a constant Cp,

and so cools down through the jacket/heat exchanger.

Isothermal

The heat exchange medium is assumed to be at a constant

temperature. For example, condensing steam or evaporating

refrigerant.

The remaining values required for the operating conditions section

are:

Batch start temperature

The temperature of the batch at the start of the time period being

considered.

Inlet temperature of the HE medium

This is the temperature of the heating/cooling medium as it enters

the coils/jacket/exchanger. For the isothermal case, this is its

temperature throughout the coils/jacket/exchanger.



and either:

Final Temperature of Batch

This is the target temperature of the batch. PEW divides the

progression towards this into ten equal increments to show how

the temperature varies during the heating/cooling period.

OR:

Duration of Heating

The time for which heating or cooling is occurring. The program

divides this into ten equal intervals to display the temperature of

the batch as a function of time.

Vessel Data Select the Type of Vessel from one of the following:

Jacketed

Heat exchange occurs within the vessel the batch is assumed

perfectly mixed with any deviations from this being

accommodated by changes in U.

OR:

External HE

The batch is constantly pumped out of the vessel and through an

external heat exchanger. The user must supply the flowrate of the

batch through this external exchanger (assumed to be

countercurrent).

Additional vessel data required is:

Mass of batch

The total mass of the batch. This should include the mass of

anything to be heated/ cooled simultaneously the vessel for

example.

Specific Heat of Batch

The specific heat (not a function of temperature) of the batch.

This must take account of the effect of including the vessel etc.

in the batch mass to be heated.

Heat Exchange Data Enter values for:

Heat Transfer Area

This is the effective area for heat exchange given the U assumed.

Overall Heat Transfer Coefficient (HTC)

The U value for the vessels jacket/coils or the external HE.

Supplementary Data Enter values for:

Flow of Batch through HE

This is only required when you have specified an external heat

exchanger and is the rate at which the batch liquid is pumped

through that exchanger.

Flowrate of HE medium

The flow of the heat exchange medium through the

jacket/coils/exchanger. This is only required when a non-

isothermal heating/cooling medium is specified.



Specific heat of HE medium

The specific heat of the heat exchange medium. This is only

required when a non-isothermal heating/cooling medium is

specified.

2.2.2.5. Simple Heat Exchanger

This program models the exit temperatures, the duty and the log mean temperature difference for a

heat exchanger given the inlet temperatures, flowrates and specified heats, heat transfer area and

overall coefficient.


Hot/Cold stream inlet

temperature

Enter values for the inlet temperatures of the streams to the

exchanger for both hot and cold streams these being defined as:

Hot stream

The stream to be cooled down.

Cold stream

The stream to be heated up.

Hot/Cold stream

thermal flow

Enter values for thermal flows of the hot and cold streams.

These can be calculated for each stream by multiplying the flowrate

of the stream by the average heat capacity of the stream.

UA value This is the product of the overall heat transfer coefficient and the heat

exchanged area.

Flow arrangement The pipes in the heat exchanger can be arranged as either:

counter current

co-current

a mixed arrangement of both.

2.2.2.6. Tank Solar Heating

This program calculates the incident solar radiation to flat-topped cylindrical tanks. It calculates

the radiant heat at intervals throughout the day, the peak energy input and the total insolation

during the day. Allowance is made for the effects of latitude, time of year and cloud cover.


Month/Day of the

month

As the amount of solar radiation varies through the year, the date for

the calculation must be specified. as Month and Day of the month.

The default values are the current date.

Latitude Enter a value for the latitude of the tank's position.

Enter a negative value to indicate the southern hemisphere.

A typical value for mid-England is 55.

Tank diameter Enter a value for the Tank diameter.

Tank height Enter a value for the Tank height.



Coefficient of air

transparency

Typical values of the air transparency vary between 0.7 and 0.85.

If in doubt use a value of 0.8.

Cloudiness factor The Cloudiness factor varies from 1.0 for a cloudless day to 0.7 for

heavy cloud.

2.2.2.7. Finned Tube

This program calculates the outside film coefficient and pressure drop for fluid flowing over a

rectangular bank or plain or finned tubes. The tubes in successive rows can be either in-line or

staggered.


Tube type Mandatory.

Select from either:

Plain

Low fin

High fin.

Layout Select for either:

Inline

Staggered

Equatorial.

Tubes Enter values for:

Lateral spacing

This is the distance between centres of tubes in the same tube

row.

Row spacing

This is the perpendicular distance between centres of tubes in

adjacent rows. This is not needed for equilateral layouts.

Length

The length of the tubes.

Tubes per row

Enter the number of tubes in each row.

No of rows

Enter the number of tube rows.

Roughness

Enter the roughness of the tube surface. This is only needed for

plain tubes.

Base tube diameter

The outside diameter of the tube.

Note. The „Roughness‟ field is not available when Low or High fin

have been selected for „Tube type‟.



Fins This part of the form is only available when Low or High fin have

been selected for „Tube type‟.

Enter values for:

Height

Enter the height of the fins on the tube. For Lowfin tubes the

maximum height is 6.35mm and for highfin tubes the maximum

is 50mm.

Thickness

Enter the thickness of the fins on the tube.


Enter a value for the thermal conductivity of the fins. This is not

required for plain tubes.

Select one of the following:

Fin pitch

This is the distance between the centre lines of successive fins. It

is the reciprocal of Fins/m.

Fin gap

Fin gap, or fin spacing is defined as the distance between the

inside faces of neighbouring fins.

Fins per metre

Enter the number of fins per metre of tube length.

Fluid Enter values for:

Flowrate

The flowrate of the gas over the bank of tubes.

Viscosity

Enter the viscosity of the gas flowing over the tube bank.


Enter the thermal conductivity of the gas flowing over the tube

bank.

Specific heat

Enter the specific heat of the gas flowing over the tube bank.

Density

Enter the density of the gas flowing over the tube bank.



2.2.3. Mixing Inputs

The following are the different types of calculation available for Mixing:

Vortex Profile

Power Numbers

Speed/Power curves.

2.2.3.1. Vortex Profile

This program calculates the shape of the vortex produced by an agitator in a circular unbaffled

tank. It applies only to agitators mounted on a vertical shaft at the axis of the vessel. The shape is

described by the heights of the liquid at the centre, agitated blade tip and circumference of the

vessel.


Vessel Diameter This is the inside diameter of the stirred vessel.

The calculation only applies to unbaffled vessels.

Agitator Diameter This is the overall diameter of the agitator blades.

Agitator Speed The agitator speed is used to calculate the angular velocity of the

batch both in the forced vortex core and in the free vortex which

surrounds it.

It is these vortices that cause the depression of the free surface.

Batch Static Height This is the total depth of liquid in the vessel with the agitator not

running.

It is not currently used in the calculation, but is included so that its

relation to the calculated differences can be easily seen.

Batch Static Height This is the total depth of liquid in the vessel with the agitator not

running.

It is not currently used in the calculation but is included so that its

relation to the calculated differences can be easily seen.

dc/D The forced vortex is that part of the batch which rotates at the same

angular velocity as the agitator itself. The size of the forced vortex

determines the overall shape of the free surface.

dc/D is the ratio of the forced vortex diameter (dc) to the agitator

diameter (D).

This option should be used for disc turbines with the default value of

0.73.

Use a value of 0.73 if in doubt over other types.

OR: Agitator Blade Width This is the width of the agitator measured in a plane parallel to the

agitator shaft. It is not the actual blade width if the blades are

inclined.

This is used to estimate the forced vortex core size using a correlation

which is only valid for flat paddles.

Use the dc/D option if in doubt.



2.2.3.2. Power Numbers

This is a pair of reference tables of power numbers for various configurations of agitators in

baffled and partially baffled tanks under fully turbulent conditions.

A pair of options toggles between the tables for baffled and partially baffled data.

2.2.3.3. Speed/Power curves

This program enables the evaluation of either agitator speed given the power input or the power

required by an agitator given the agitator speed.

The program uses fitted data from curves of Power Number as a function of Reynolds Number and

applies correction factors for „non-standard‟ geometries.


Give This determines the calculation type.

Select one of the following:

Speed

The speed and geometry need to be defined and the program

calculates agitator power.

Power or Power/Vol

The power requirement is given either as power or power per

unit volume together with the geometry. The program calculates

agitator power.

General Select one of the following (this is dependent on which option was

chosen above in Give):

Speed

The rotational speed of the shaft on which the impeller(s) is/are

mounted.

OR:

Power

The power required to drive the agitator(s).

OR:

Power/Vol

The power required to drive the agitator(s) expressed per unit

volume.

Enter the following values for the remaining General conditions:

Vessel Diameter

This is the fundamental quantity from which most of the others

are derived.

Once this value has been entered, the other quantities are entered as

standard defaults by the program. These can be changed by the user

as required.

Bottom shape

This is the shape of the vessel bottom. A correction factor is

applied if the user specifies a flat bottom – the default value is

„Dished‟.



Agitators Up to three impellers can be specified on a shaft. Once the first

agitator is specified, the second and third are restricted to those types

that can be correctly combined in this way.

General options that can be specified for the agitators are:

The number of impellers of the first type (1 to 3)

If there are several identical impellers on the shaft then they only

have to be defined once. Use this input to define how many

identical impellers are present.

Several non-identical impellers can be defined – see below for

details.

Clearances

The clearance is the distance from the agitator to the bottom of

the vessel. There are two options – Default and Supplied:

Default

The program does not ask for clearance information and positions

the agitators at the recommended clearances.

Note that the program moves them if the number of impellers are

changed as this determines the clearances.

Supplied

The user is asked to enter clearances. The program checks that

these are sensible values and displays warnings if they are not.

The convention for ordering the impellers in this program is from

the bottom of the vessel up. This is how they are arranged if

„Default‟ clearances are selected. If the supplied clearances that

indicate the impellers are in a different order, the calculation

engine automatically renumbers them for the purposes of the

calculation.

Select the impeller type from the drop down box. Select one of

the following:

Rushton

Flat Blade

45 Pitched

60 Pitched

Propeller

Anchor

Gate

Concave.

Options for the second and third impeller are restricted by the

choice for the first.

The following details the required inputs for each impeller type:

Rushton

Number of blades

The number of impeller blades.

Impeller Diameter

This is the most important data describing the impeller. If it is

changed, the other dimensions of the impeller are reset

automatically (these can be subsequently corrected if required).



Clearance


the vessel. The program sets this automatically if default

clearances were set at the previous prompt.

Multiple impellers can be specified in any order but they will be

arranged automatically at the end of editing so the first is the

lowest.

Blade width

The dimension across the impeller blade.

Blade thickness

The dimensions through the thickness of the blade.

Blade length

The length of a single blade.

Disc diameter

The diameter of the disc on which the blades are supported.

Disc thickness

The thickness of the disc on which the blades are supported.

Flat Blade

Number of blades


Impeller Diameter




Clearance



clearances are set at the previous prompt.



lowest.

Blade width


Blade thickness


45 and 60 Pitched

Number of blades


Impeller Diameter




Clearance








lowest.

Blade width


Blade thickness


Angle

Blade angle to vertical.

Blades pumping

Whether the impeller pumps the liquid up or down.

Propeller

Number of blades

The number of impeller blades – the limit is three for this

impeller type.

Impeller Diameter




Clearance






lowest.

Propeller pitch

This can be compared to the pitch of a screw thread. It is the

distance that would be travelled by the propeller it is was turned

one revolution in a solid medium.

Typical values range from D->2D where D is the diameter of the

propeller.

Anchor

Impeller Diameter




Clearance






lowest.

Edge clearance

The clearance of the anchor from the walls of the vessel.

Number of cross bars

The number of horizontal bars that help to support the vertical

bars of the gate.



Arm thickness

The radial distance through the anchor blade.

Impeller height

The height of the anchor from its lowest point in the centre to the

tops of its arms.

Blade shape (round/flat)

The shape of the anchor. This makes a difference in the clearance

correction for the laminar and transitional regimes.

Gate

Impeller Diameter




Clearance






lowest.

Edge clearance

The clearance of the anchor from the walls of the vessel.

Number of cross bars

The number of horizontal bars that help to support the vertical

bars of the gate.

Vertical bar spacing

The external diameter of the vertical bars.

Arm thickness

The radial distance through the anchor blade.

Impeller height

The height of the impeller.

Blade shape (round/flat)

The shape of the anchor. This makes a difference in the clearance

correction for the laminar and transitional regimes.

Concave Blade

Impeller Diameter




Clearance






lowest.

Blade width




Blade thickness

The dimension through the thickness of the blade.

Blade radius

The length of a single blade.

Disc diameter

The diameter of the disc on which the blades are supported.

Disc thickness

The thickness of the disc on which the blades are supported.

Internals/Conditions The batch conditions are specified by entering the following data:

Batch depth

The depth of liquid in the vessel measured from the deepest

point.

Liquid density

The average density of the liquid in the vessel.

Liquid viscosity

The normal (dynamic) viscosity of the liquid in the vessel. Note

that these calculations are the Newtonian liquids only.

The batch internals are chosen from a drop down box. The options

available are:

None

3, 4 or Normal Baffles

1 or 2 Beavertails

1 or 2 Two Finger Baffles

1 or 2 Dip Pipes

Profiled

Helical Coil

Ringlet Coil

Additional information is required for the Normal Baffles option and

for the Helical Coil option.

Note. Dip Pipes and Ringlet Coils have no effect unless the vessel

is unbaffled. If they occur in baffled vessels, their additional

effect can be ignored and the baffles themselves only have to

be specified.

Normal Baffles

The following additional information is required:

Baffle width

The distance by which each baffle protrudes into the vessel.

Baffle Height

Baffles are normally either full or half height. The program

handles non full height baffles by regarding any impeller above

the baffles as unbaffled and any impeller with any part within the

baffles as fully baffled.

The type of baffle height specification – the height of the baffle

can either be described as a fixed proportion of the liquid height

or as a specific height.



Full

The baffles are always taken to be the same height as the liquid

in the tank.

Half

The baffles are always taken to be half the height of the liquid in

the tank.

Given

The user is prompted for a baffle height.

This height will not be reset by the program if you change the

batch height – this can be changed by the user as required.

In the calculation, if an agitator has any part of itself within the

baffled region it is treated as fully baffled. If it lies entirely

outside the baffled region it is regarded as unbaffled.

Baffle spacing

The gap between the baffles and the wall. This is relevant if

fouling is a problem. If space is present it is normally T/40 or

T/60 where T is the tank diameter but the exact value is not

critical.

Select either of the following:

None

No gap between the baffles and the vessel walls.

T/60

A gap 1/60 the size of the vessel diameter (T).

Only a limited set of data is available for baffles for 45 and 60

Pitched blade impellers. The data set is restricted to:

Four Baffles

Wall-gap

4*T/12 flat wall baffles + T/40 wall-gap.

No-gap

4*T/10 flat wall baffles + No gap.

Half-Height

4*T/12 + wall-gap. Half height wall baffles.

Helical Coils

The following additional information is required:

Tube diameter

The diameter of the tubes from which the coil is composed. This

is only required to check that the coils are not too closely spaced.

Tube Pitch

The gap between the coils. This is only required to check that the

coils are not too closely spaced.



2.2.4. Equipment Inputs

The following are the different types of calculation available for Equipment:

Vessel Calibration.

2.2.4.1. Vessel Calibration

This program calibrates depth, wetted area and volume for cylindrical tanks which may have flat,

ellipsoidal, dished or conical ends independently of one another. Dished and conical ends may

have a transition knuckle and the axis of the tank can be horizontal, vertical or inclined.

See Appendix C for more information on Vessel Calibration.


General data Mandatory.

Select Orientation from one of the following:

Horizontal

Vertical

Inclined.

Enter the height of the upper end above the base in the Upper

end height field.

Select from either:

Total

Cylinder Length

Enter values for:

Total/Cylinder Length

Dependent on which option was chosen above – the total length

of the vessel including ends or the cylinder length.

Cylinder Diameter

The diameter of the central cylinder.

Density

The density of the liquid or solid in the tank – used to relate the

volume of the contents to the mass.

Note. All dimensions are vessel internal dimensions.

Enter the following if the vessel axis is inclined:

Upper and Height

Height of the upper end above the base.

End dimensions Enter values for:

Shape

Each end of the vessel can be either:

Flat

Straight across the end of the cylinder.

Conical

A cone with a rounded end which is linked to the main cylinder

by a transition knuckle.



Ellipsoidal

An elliptical end with no transition knuckle.

Dished

Rounded end that is linked to the main cylinder by a transition

knuckle.

Enter the following depending on the type of shape chosen:

Diameter of small end

The diameter of the rounded end of the cone which is only

required for conical ends.

Cylinder end distance

The distance from the end of the cylindrical portion of the vessel

to the end of the cone which is only required for conical ends.

Dished end radius or minor axis

This is required for ellipsoidal and dished ends and has the

following definitions:

Ellipsoidal

The minor radius of the ellipse.

Dished

The radius of the dished end.

Radius of transition knuckle

This is required for conical or dished ends which are assumed to

be joined smoothly to the main cylinder by a curved transition

knuckle.

Calibration The vessel can be calibrated for the volume, mass or depth of

contents.

Select Calibrate from one of the following:

Volume

Mass

Depth.

Select Points from one of the following:

Number

Select the number of points to be calibrated, up to a maximum of

20 and the increment size is calculated by the program to cover

the whole vessel.

Increment

Specify an increment size, and the program calculates increments

starting at the base of the vessel until the whole vessel is

calibrated, or 20 points are reached. If the increment size is too

small to calculate the whole vessel, a warning message is given,

an the final point gives the values when the vessel is full.

Given

The program can also calibrate to Given points. Set the number

of points required (up to a maximum of 10) and supply each

point in the given points fields. This allows uneven spacing of

the calibration points.



2.3. Calculation Type – Fittings Form

The „Fittings‟ form allows Fittings losses to be specified for the compressible and incompressible

flow calculation.

The forms are only available for:

Fluid flow – Incompressible

Fluid flow – Compressible.

The Fittings form is shown in Figure 3.

Clicking the Edit pipe . . . button toggles between the Fittings section of the form at the bottom of

the „In/compressible flow‟ window and the „In/compressible flow‟ section at the top of the

„Calculation Type‟ window.

Figure 3 Fittings section of the In/compressible flow window

The following selections can be made from this dialog:

Usage

90 degree bend The following define the type of bend:

Circular A smooth bend that turns through a right angle.

2 cut mitre A bend with two elbows in it of 45 degrees each.

3 cut mitre A bend with three elbows in it of 30 degrees

each.

Note. For a 45 degree bend multiply the figure by 0.7 and for 180

degrees multiply by 1.4. These figures can be entered in the

„Miscellaneous losses‟ cell.

Radius/Diameter This is the ratio of the radius of curvature of the

bend to the internal diameter of the pipe (The

radius of curvature is taken to the centre line of

the pipe).



Usage

Elbows The following define the type of elbow:

30 degrees A sharp turn through 30 degrees




Dead leg T junction A T-Junction with one leg blanked off with only one entry and one exit

of the same diameter.

Flow into leg The flow is into the blanked off part.

Flow out of leg The flow is across the blanked off end (there is

very little loss for flow past a blanked-off

branch).

Rectangular port

plug valve

The size of the port relative to the pipe area is shown in the prompt.

Circular port plug

valve

The port size is the same as the pipe area for this data.

Other valve types The values given for the following valves are all for turbulent flow

through a fully open valve (see R A Smith).

The adjustment factors for partly closed valves are given for each

valve type.

To account for a partly open valve, multiply the heads lost by the

factor, and include the result in miscellaneous losses.

Globe valve There is no data for forged globe valves larger than two inches nominal

diameter.

% open 20 40 60 80

Factor 4 2 1.2 1.0 (approx.)

Gate valve Here the seat area is assumed to be the same as the pipe area. Note

there is no data for valves smaller than 4 inches nominal diameter.

% open 20 40 60 80

Factor 200 30 8 3 (approx.)

Diaphragm valve % open 20 40 60 80

Factor 9 4 2 1.5 (approx.)

Butterfly valve The thickness of the valve is shown in the prompt.

% open 20 40 60 80

Factor 1000 50 9 2 (approx.)

Miscellaneous losses This can be used to enter any losses not specifically listed on the form.

Edit pipe … Clicking this button toggles between the Fittings section at the bottom

of the window and the Inputs section at the top.



2.4. Calculation Types – Results Forms

The Results form displays the calculation results.

The screen in Figure 4 shows the result when a „Calculation type‟ of Fluid flow/Incompressible

was calculated.

Figure 4 Results section of the Calculation Type window

Usage

Warning/errors Any warnings messages that might have been generated while PEW

was performing the calculation are displayed in this field in red text.



2.5. Handling Calculation Results

The following buttons on the toolbar (see section 2.7) allow the user to handle results in the

following manner:

Printing Results

Creating a Graph

Creating a Summary Table.

2.5.1. Printing Results

On the Project menu clicking Print, or clicking the toolbar Print button, lets you select the

following print options:

Current calculation Prints the current calculation.

Current graph Prints the current graph.

Summary Prints the Summary Table.

Units Prints the Unit Settings form (see section 2.6.6 for more information).

Whole Project Prints the whole project comprising the units settings, all the

calculations and any summaries or graphs that have been created.

2.5.2. Creating a Graph

Clicking this button generates a graph of the calculation.

See section 3.2.8 for an example.

2.5.3. Creating a Summary Table

Clicking this button generates a Summary Table of the calculation.

One a blank summary page has been created, cases and variables must be added to generate the

summary. This is performed using the Summary/Add/Cases and Summary/Add/Variable menu

items (see section 2.6.4 for more information on the „Summary‟ menu and section 3.2.9 for an

example of how a Summary Table is created).



2.6. PEW Menus

This section lists the various menus and describes the options that are available. Keyboard

shortcuts are shown in brackets.

2.6.1. Project Menu

The Project menu allows you to access the following options:

Menu Option Definition

New Creates a new .PEW project file.

If there are any cases on the workbench, PEW prompts to save the current

project first. The workbench will be re-initialised and all current cases,

summaries and graphs removed.

Cancel returns to the current project.

Open (Ctrl-O) Opens an existing .PEW project file

PEW prompts to save an existing project if appropriate. Once a project has

been selected, the current project is closed and the selected project opened.

Include Allows two or more projects to be combined.

An existing project can be selected to add to the current project. All data in

the current project, including the project name if set, remain, and the new

data is added to it.

Save (Ctrl-S) Saves the project with the current filename (if one exists) and a .PEW

extension. Otherwise, PEW will prompt for a filename.

All the cases in the current project are saved into one file with the specified

filename and can be reloaded into PEW using the Project/Open command.

Save As (Ctrl-A) Save the current project with a different filename.

Print (Ctrl-P) Allows the following print options:

print the current calculation, summary or graph.

print Units.

print the whole project.

To print a specific case, select it before choosing Project/Print.

See section 2.5.1 for more information.

Print Setup Displays the print setup dialog that allows settings (portrait, landscape etc.)

to be changed.

Exit First prompts to save the current project then exits and closes PEW.



2.6.2. Calculation Menu

The Calculation menu allows you to access the following options:


Add Lists the calculation types available and creates a new case of the

calculation chosen.

The calculation types in PEW are divided into four groups: fluid flow, heat

transfer, mixing and equipment. Multiple cases of the same calculation type

can be opened.

Copy Creates a copy of the current calculation.

Any data contained in the current calculation, including any calculated

results are copied to the new calculation. This option can be used where a

number of calculations on similar sets of data are required. Each calculation

case only holds the data that is currently entered on it, and previous data

will be lost, unless a copy of the calculation is used to carry out the next

calculation.

Calculate (F9) Runs the calculation for the currently selected case.

The case data must be visible on screen, that is, the case must be shown in a

window. This is because the data for minimised cases is stored temporarily

to make more resources available to the system.

Delete Displays a warning and deletes the currently selected case unless Cancel is

chosen.

Make default Makes the current case into the default for that calculation type.

Subsequent new calculations of that calculation type have the initial data

and units of the current case. These values are used in subsequent runs of

PEW until a new case is made into the default or the built-in values are

reset. This option can be used to specify a customised set of units for each

calculation type.

The data for the default cases is saved in a file called PEW.INI in the

WINDOWS directory. To reset the default case to the built-in values either

delete PEW.INI or edit it to remove the data for the relevant calculation

type.

2.6.3. Edit Menu

The Edit menu allows you to access the following options:


Copy Copies the selected text to the clipboard.

Paste Copies the text from the clipboard to the current field.

Copy Calculation

To clipboard

Copies the calculation result to the clipboard.



2.6.4. Summary Menu

The Summary menu allows you to access the following options:


Create Creates an empty summary form to which the required cases and variables

must be added.

Refresh Updates the form with the latest information.

Add First select:

Case One or more cases to add can be selected from the list of

cases in the project. This can include cases which are

currently visible or minimised. Cases of different calculation

types can be added. If there is more than one summary in the

project, the cases are added to the current summary.

A summary can hold twenty cases.

Then select:

Variable Once a case has been added to the summary, up to seven

variables can be selected to display on the summary. A list of

the variables available for all the cases on the summary is

shown. If more than seven variables are selected, the first

seven will be added and a warning given. Create another

summary to show more than seven variables.

Delete Select one of the following:

Case One or more of the cases on the current summary can be

deleted together with the variables associated with them.

A variable type cannot be removed from the summary even

if all the cases on which it appears are removed. If all cases

on the summary are deleted, the summary is also be deleted.

Variable Any of the variables on a summary can be deleted.

The cases remain so the summary is not deleted even if all

the variables are deleted.

Graph A bar graph can be created to show any of the data on the current

summary form.

A list of cases on the summary is provided followed by a list of the

variables on the summary, to choose from. These summary graphs can be

titled, saved with the project and printed. However, the data on them

cannot be changed after creation and the graphs are not updated if the

cases or summaries change.

For an updated version delete the old graph and create a new one.

Note. To select multiple cases or variables at one time:

Hold down the Ctrl key while clicking the selections to be chosen.



2.6.5. Graph Menu

The Graph menu allows you to access the following options:


Create Creates a graph to which variables can be added.

The graph plots the values of the same variable on each case of a given

calculation type. There must be at least two cases of the same type for a

graph to be drawn.

The program provides a list of the available calculation types. It then

prompts for the X and Y axes from all the variables in the selected

calculation type. If there are not enough calculations of any type to create a

graph, the program displays a warning.

X axis Lists the variables available to select for the X axis.

This can be used to change the x axis on the current graph.

Y axis List the variables available to select for the Y axis.

This allows the Y axis of the current graph to be changed.

Second Y Adds a second Y variable to the graph.

Delete second Y Deletes the second Y added by the option „Second Y‟.



2.6.6. Units Menu

The Unit menu allows you to access the following options:


Open Opens the Units form (see Figure 5 below) to allow any unit to be changed

or to use a different set of units.

Changes to a unit take effect on all forms as soon as the focus is moved

from the changed unit. This may take some time on a large project. Clicking

Done on the form closes the form so giving a slight increase in available

resources.

Show If the Units form is open, clicking Show brings the form to the top and

gives it focus. The effect is the same as clicking Units on the Window

menu.

Close Closes the Units form.

Figure 5 Units Form

There are three predefined sets of units:

Engineering

SI

British.

Click the appropriate button to select a set of units. The selected unit set appears in the cells at the

bottom of the form.

Changes to the current choice can also be made by typing the new unit into the appropriate cell. If

the newly entered unit cannot be converted from the existing unit a warning appears and the

change does not take place.



Additional sets of units can be saved from the „Save units set‟ button. A prompts asks for a name

and the units are saved in a file PEW.INI in the Windows directory. There is no limit to the

number of unit sets but, if the same name is used twice, the new units set overwrites the old unit

set with the same name.

To reload a saved units set, click User and select the required set from the list.

The default units set is initially „Engineering‟. To change the default, first select the new units set

then click Make default. The new units set is automatically loaded each time PEW is started. The

„Default‟ option also selects this unit set.

2.6.7. Tools Menu

The Tools menu allows you to access the following options:

Pipe Inner Diameter Calculator

Molecular Weight Calculator

K-value Calculator

Pipe Roughness Calculator

Calculator

Text Editor.

Calculate Physical Properties

Calculate Physical Property

These are detailed in the following sections.



2.6.7.1. Pipe Inner Diameter Calculator

This dialog is used to calculate the pipe inner diameter.

Select a standard pipe size then the available schedules for that pipe size. The details for that

combination are displayed at the bottom of the dialog box.

Figure 6 Pipe Inner Diameter Calculator dialog


Usage

Standard Pipe Sizes Lists the pipe sizes available from 1/8 to 36.

Schedules Available Lists the pipe schedules available for the pipe size selected.

Inner Diameter Displays the Inner Diameter of the selected pipe.

Wall Thickness Displays the Wall Thickness of the selected pipe.

Outside Diameter Displays the Outside Diameter of the selected pipe.

Return Select which value is to be returned to the program. The default is

Inner Diameter.

OK Click OK to return the chosen value to the program. The value is

pasted into the cell that was highlighted when the Pipe Inner

Diameter Calculator was selected.



2.6.7.2. Molecular Weight Calculator

This calculates the molecular weight of a compound given its formula. The following rules are

used to interpret the formula:

Elements are given their usual atomic symbol, for example, He for Helium and O for Oxygen.

The first character must always be upper case and the second (if there is one) lower case. This

enables the Molecular Weight Calculator to distinguish formulae such as PO and Po. The

calculator regards the first of these as Phosphorous and Oxygen and the second as the element

Polonium.

No other symbols are recognised, for example, common groups like benzene rings, ethyl

groups etc.

Elements can be followed by numbers and are separated by spaces, dots or colons.

Brackets can be used as required to any level. For example, CH3(CH2)10CH3 would be one

way of describing Dodecane (see Figure 7). However, note that in this example the 10 refers to

the CH2 group, not the succeeding CH3. Thus water of crystallisation must be specified as

Na3SO3(H2O)5.

The atomic weights used by the Molecular Weight Calculator are taken from Perry‟s Chemical

Engineers Handbook.

Figure 7 Molecular Weight Calculator dialog


Usage

Enter Chemical Formula Enter the chemical formula then click the „=‟ button to calculate

the molecular weight.

Mol. Weight Outputs the molecular weight for the formula entered.

The molecular weight calculated is automatically pasted into the

cell that currently has focus when the dialog is closed. If this cell

does not accept the value it is pasted to the clipboard instead.

OK Click OK to paste the calculated value into the cell that was

selected when the Molecular Weight Calculator was run.



2.6.7.3. K-value Calculator

The Fittings Loss (K-value) calculator consists of a number of sections where the fitting's details

of a pipe are built up. The front sheet of the dialog contains a summary of the following sections:

Tee Junctions

Bends

Valves

Expansions/Contractions

User Defined (Process Equipment)

Manual Adjustment.

Figure 8 Fittings Loss (K-value) Calculator dialog


Usage

Summary Tab:

- Sub Total Outputs the sub total before a manual adjustment is added.

- Manual Adjustment The manual adjustment field is for entering miscellaneous fittings.

It is also used for manually adjusting the model in the validation

stage or for studying the effect of changes, for example, changing

a control valve position.

- Reason for Adjustment Text describing the reason for adjustment can be entered in this

field.

- Overall Total Outputs the overall total combining the sub total and the manual

adjustment to produce the fittings loss value for the fitting.



Tee Junctions Tab: The Tee Junctions calculation takes into account any blanked off

junctions. This can also be a line where the dead leg is isolated at

a valve further downstream.

Add a Tee

Junction:

Select a Tee Junction Type, enter the

Quantity and click Add. The entry is added

to the list at the bottom of the sheet.

Remove a Tee

Junction:

Select the Tee Junction then click Delete.

An example of a typical Tee Junction tab display is shown below:

Bends Tab: Bends are entered and deleted using the same method as for Tee

Junctions.

An example of a typical Bends tab display is shown below:



Valves Tab: Valves are entered by selecting a valve type then double-clicking

it.

This displays the various categories of valve available for that

type, for example, the Globe Valve type has two categories – cast

valves and forged valves (see below).

Add a Valve: Click the category required and select a

valve from the „Pipe Size (Nominal Bore)‟

drop down list. Specify how many of these

valves are required in the „Quantity‟ box

then click Add.

Delete a valve: Select the valve from the list and click

Delete.

An example of a typical Valves tab display is shown below:

Contractions/Expansions

Tab:

Click either Expansion or Contraction then follow the same

method as for Tee Junctions.

For exit losses: Select an expansion with a small/large area

ratio of zero.

For entry losses: Select a contraction with a small/large area

ratio of zero.

An example of a typical Contractions/Expansions tab display is

shown below:

User Defined (Process

Equipment) Tab:

The easiest way to model process equipment (for example, heat

exchangers and filters) is as a section of pipe with a fitting loss

coefficient.

The pipe length needs to be short so that the pressure drop is

solely due to the fittings 1m is generally used.

The values for mass flow, pressure drop etc. can be obtained from

the process datasheet.



Static head changes between inlet and outlet should not be taken

into account as the node information deals with this.

An example of a typical User Defined (Process Equipment) tab

display is shown below:

Note. The K-value is automatically posted into the cell that is currently active when the K-value

dialog is closed. This value is pasted to the clipboard if the cell does not accept the value.

2.6.7.4. Pipe Roughness Calculator

This calculator is used to select a Surface Type and Absolute Roughness. Clicking OK then adds

the selection to the calculation.

The units of measurement for roughness depend on the program calling the Pipe Roughness

Calculator. Those for PIPER are in mm. For other programs (for example, FLONET) the Pipe

Roughness Calculator displays and returns the relative roughness based on the relevant pipe

diameter.

By default, the units are in mm for PEW and the Absolute Roughness is returned.

Figure 9 Pipe Roughness Calculator dialog

2.6.7.5. Calculator

Opens the Windows Calculator to assist with your calculations.

2.6.7.6. Text Editor

Opens the Notepad text editor.



2.6.7.7. Calculate Physical Properties

The PPDS Calculator is used to calculate physical properties for a fluid, such as its density and

viscosity.

The properties to be calculated depend on which type of calculation case the calculator is run from.

The example dialog shown in Figure 10 is run from an Incompressible Flow form. On some forms

the properties are grouped into more than one stream. For example, for the Two Phase flow form

liquid and gas properties are grouped separately. Similarly, the pipe and vessel heat loss forms

group have properties at several different temperatures.

The dialog consists of two separate sections. The component section at the top of the dialog lets

you define the constituent parts of the fluid. Whenever you open the calculator the table always

contains the last values used. This lets you run multiple calculations on the same fluid without

having to specify the fluid each time. The lower section of the dialog is the properties calculator

itself.

Figure 10 PPDS Calculator dialog


Usage

Component section:

Add Component Opens a search dialog to let

you add a component to the

table.

Select a Databank to search

and type a search string.

Select the required

component in the results list

and click Add to stream.

Add as many components as

you need then click Close.



Clear Worksheet Clears the values you used last time, so that you can specify a new

fluid.

Select Units Opens a separate dialog that lets

you specify the units for

Temperature

Pressure

Molar Amount

Mass Amount

To change a unit, right-click the

cell and select an alternative in

the shortcut list. Then click OK.

Mol Wt The molecular weight is automatically entered for the component and

cannot be changed.

Molar (kmol) Enter the molar amount of each component.

Mol. Fraction Enter the molar fractions or relative amounts of each component.

(these are then normalised and displayed as fractions).

Mass (g) Enter the mass amount of each component.

Mass Fraction Enter the mass fractions or relative amounts of each component.(these

are then normalised and displayed as fractions).

Calculator section:

Phase Select one of the following from the list:

Liquid, Vapour, Ideal Gas

Temperature,

Pressure

Enter the temperature and pressure to be used in the calculation.

You can enter these in different units (see Appendix A)

Calculate Click Calculate to compute values for the properties

OK Click OK to paste the calculated values into the group of cells, one of

which was selected when the PPDS Calculator was run.

2.6.7.8. Calculate Physical Property

This second option also calls the PPDS calculator, but only to calculate a single fluid property.

2.6.8. Window Menu

This menu consists of the standard Windows options, that is, Cascade, Tile (horizontal and

vertical), Arrange Icons and a list of all available windows.

2.6.9. Help Menu

The Help menu provides on-line help information, a search facility and the latest version

information.



2.7. The PEW Toolbar

The toolbar buttons run the following commands:

Button Purpose

New Project

Creates a new PEW project.

Equivalent Project menu item New

Open a saved Project

Opens an existing (saved) PEW project

Equivalent Project menu item Open

Save Project

Saves the PEW project currently open.

Equivalent Project menu item Save

Print the current Project

Print the current PEW project.

Equivalent Project menu item Print

Add a new Case

Displays the „Calculation type‟ dialog.

Equivalent Calculation menu item Add

Copy the current Case

Creates a copy of the current calculation.

Equivalent Calculation menu item Copy

Calculate the current Case

Runs the calculation for the currently selected case.

Equivalent Calculation menu item Calculate

Delete the current Case

Displays a warning and deletes the currently selected case unless Cancel is chosen.

Equivalent Calculation menu item Delete

Create a Summary

Creates an empty summary form to which the required cases and variables can be

added.

Equivalent Summary menu item Create a Summary

Create a Graph

Creates a graph to which variables can be added.

Equivalent Graph menu item Create a Graph

Set X axis for Graph

Lists the variables available to select for the X axis.

Equivalent Graph menu item Set X Axis



Button Purpose

Set Y axis for Graph Text . . .

Lists the variables available to select for the Y axis.

Equivalent Graph menu item Set Y Axis

Add a variable to the current summary

One or more cases can be selected and added from the list of cases in the project.

Equivalent Summary menu item Add a case to the current summary

Add a case to the current summary

One or more variables can be selected and added from the list of variables in the

project.

Equivalent Summary menu item Add a variable to the current summary

Set numeric format for the calculations

The selection can be made from one of the following formats:

3

3.1

3.14

3.142

3.1416

3.14159

3.141593

3.1415927

This sets the number of significant figures, not the number of decimal places.

This means that choosing the fourth option „3.142‟ indicates that only four significant

figures will be displayed. The value „12345‟ would be displayed as 12350 under these

circumstances.

Display PEW helpfile

Displays the PEW on-line help.

Pressing F1 while a particular cell is selected displays the help file for that input

value.



3. PEW Tutorial

3.1. General

This example details the procedure to calculate the flowrate of water in 500 feet of 2 inch unlined

cast iron pipe up a 10 foot incline for pressure drops between 0.5 and 3 bar diff. There is one 90

circular bend in the pipe and five velocity heads lost in other fittings.

3.2. Solving the Network

The procedure to solve the network involves the following steps:

Accessing PEW

Selecting the Calculation type

Entering data on the Inputs form

Entering data on the Fittings form

Performing the Calculation

Repeating the calculation for other values.

The results can then be viewed, graphed, printed and saved.

3.2.1. Starting PEW

Procedure

1. Click Start > All Programs > PEL then click the PEW icon.

Note. If using the classic Start menu or earlier versions of Windows, click

Start > Programs…

A splash screen showing the program name and version number appears briefly before the start up

screen (see Figure 1) appears.

3.2.2. Selecting the Calculation type

Procedure

1. On the Calculation menu, click Add or click the Add a new case button on the toolbar.

2. In the Calculation type window, click Fluid flow in the left pane and Incompressible in the

right pane.

Figure 11 Selecting the Calculation type

3. Click OK.

The Incompressible Flow form opens.



3.2.3. Entering pipework and losses data on the Inputs form

Procedure

1. Click Flow (just underneath the heading Calculate) to select the Flow calculation.

2. Double-click the Pipework Length box to select the default value of 10m.

3. Enter the value 500 followed by a space followed by ft. Press Enter on the keyboard or click

another input box to perform the conversion automatically (see Appendix A for more

information about in-cell units conversion).

4. Double-click the Pipework Diameter box to select the default value. On the Tools menu, click

Pipe Inner Diameter Calculator.

5. Leave the type set to Steel Pipe, Select a 2 and 40 /STD/ 40S pipe then click OK. PEW

pastes the internal diameter into the „Pipe Diameter‟ box. The Lining thickness box is not used

in this calculation as the pipe is unlined.

6. Double-click the Pipework Roughness box to select the default value. On the Tools menu,

click Pipe Roughness Calculator. Select Cast iron, concrete, timber and then click OK.

PEW pastes the result into the Roughness box.

7. Double-click the Losses Static head loss box to highlight the default value.

Enter the value 10 ft.

8. The Pipework and Losses sections now looks like this:

3.2.4. Entering data on the Fittings form

Procedure

1. Click Edit to the right of the legend „Fittings loss (velocity heads)‟ to switch to the „Fittings‟

section.

2. Go to first cell in the Number of Items column and enter the value 1 to specify a single 90

circular bend.

3. Go to the „Miscellaneous losses‟ box at the bottom of the form and enter the value 5 to specify

five velocity heads lost through other fittings.

4. Click Edit pipe to switch back to the main input form.



3.2.5. Calculating fluid properties and process conditions data

Procedure

1. Click in the Density box. On the Tools menu, click Calculate Physical Properties.

2. When the Calculator appears, if any components appear in the worksheet click Clear

Worksheet to clear them.

3. Click Add Component to open the Select Components dialog. Enter water in the Search for

Name box, select WATER in the results list and then click Add to stream to add water to the

Calculator and then click Close.

4. Enter a temperature of 20°C and a pressure of 1 bar and click Calculate. The Calculator

returns a density of 999.48 kg/m3 and a viscosity of 0.9983. Click OK to return these values to

the Incompressible Flow form.

5. Double-click the Pressure drop to select the default value and enter 0.5 bar diff.

6. The Inputs and Fittings forms of the „Incompressible flow‟ window now look like this:

Figure 12 Inputs section of the Incompressible data Input window



Figure 13 Fittings section of the Incompressible data Input window

3.2.6. Performing the Calculation

Procedure

Click the Calculate button on the toolbar. The results appear (in blue text) in the „Results‟

form on the right of the „Calculation type‟ window as shown in Figure 14 when the calculation

has finished.

Note. Any warnings or errors produced during the calculation are displayed at the bottom

of the results form in red text.

Figure 14 Results section of the Incompressible data Input window

The value 1.372 kg/s for the Mass flow appears.



3.2.7. Repeating the calculation for other values

It is necessary to repeat the calculation over a range of pressure drops between 0.5 and 3 bar. This

is performed at 1, 2 and 3 bar. However, each set of results must be saved so the calculation should

be copied before making the changes.

Procedure

1. Click the Copy button on the toolbar. This produces a copy of the first case.

Change the title from Copy of No 1 to No 2.

2. Double-click the Pressure drop field and change the value to 1 bar diff.

3. Click the Calculate button on the toolbar to re-calculate the flowrate. This should produce a

value of 2.608 kg/s for the flowrate.

4. Repeat the last three steps for pressure drops of 2 and 3 bar diff. This should produce flowrates

of 4.096 and 5.176 kg/s respectively.

3.2.8. Plotting the Graph

Procedure

1. Click the Create a graph button on the toolbar.

2. In the „Graph – select calculation type‟ dialog, click Incompressible and then click OK.

3. In the „Graph – select X axis‟ dialog, click Pressure drop and then click OK.

4. In the „Graph – select Y axis‟ dialog, click Mass flow and then click OK.

5. The following graph appears:

Figure 15 Graph of Pressure drop against Mass flow

7. On the Project menu click Print, or click the toolbar Print button, to produce a paper copy of

the graph.



3.2.9. Creating a Summary Table

Procedure

1. Click the Create a summary button on the toolbar and enter Demonstration as the summary

title.

2. Click the Add a case to the current summary button on the toolbar.

3. In the „Summary – select case‟ dialog, select all four cases, and then click OK.

4. Click the Add a variable to the current summary button on the toolbar.

5. In the „Summary – select variable‟ dialog, select Pressure drop, Massflow, Velocity and

Reynolds number as the columns for the table and then click OK.

The following Summary Table appears.

Figure 16 Summary Table

8. On the Project menu click Print, or click the toolbar Print button, to produce a paper copy of

the Summary Table.



3.2.10. Saving a PEW file

Procedure

Click Save Project.

This saves the results in a comma separated text format as a *.pew. This can then be edited

using Lotus 1.2.3 or any other spreadsheet or text editor.



Appendices

Appendix A – In-cell Units Conversion

Units conversion is available for any field where it is appropriate. The conversion is always from

the units entered to the units shown on the dialog box.

In order to perform a units conversion you should type the following information into a field:

Value_Unit

where Value is the figure to be converted, Unit is the unit to be converted and „_‟ is a space.

The units conversion (if it is possible) is performed automatically as soon the cursor is moved

from the current field, as shown below:

Example

1. Enter the value and unit 2 (inches).

2. Move the cursor off the field or press Enter. The field now shows:

3. If the conversion is not possible a message box appears and the value in the field is taken as

being in the units specified on the dialog box.



Appendix B – Choosing a Fluid Flow Program

PEL contains four programs which are capable of fluid flow calculations. These are:

PEW

ADRIAN

FLONET

PIPER

The capabilities of each of these programs are summarised below and in Figure 17:

PEW

This program can handle:

A single, unbranched pipe of a fixed diameter.

Incompressible and compressible flow calculations. Compressible flow calculations are valid

up to approximately 0.3 Ma and include isothermal and adiabatic modes.

Single phase gas or liquid.

Design calculation as well as rating calculations, that is, for a fixed flow and required pressure

drop it will calculate the pipe diameter.

ADRIAN


Rating calculations in branched networks of high velocity gas flows.

Single phase gas flows up to 1.0 Ma including modelling of choked systems.

Isothermal and adiabatic calculations.

Directed piping network (that is, the fluid flow from the beginning of the pipe to the end of the

pipe) allowing for changes in diameter and full consideration of the order in which fittings

occur.

Loop-like as well as tree-like networks with care.

Note. ADRIAN is only valid for fully turbulent flow regimes.

FLONET


Rating calculations in complex networks of single phase gas or liquids.

Isothermal calculations only and gas flow below 0.2 Ma.

Complex networks can be modelled including loop-like structures with unknown direction.

Turbulent, transitional and laminar flow regimes.

Pumps and None-Return Valves can be included in the network.

PIPER


Single phase gas or liquid and two phase flow.

Single unbranched pipe of variable diameter.

Very detailed physical properties representation allowing modelling of phase change

throughout the piping system and modelling of non ideal gases.

Allows for heat transfer through the pipe wall.

Fully models all pressure discontinuities and calculate maximum non-choked flow in a system.



Figure 17 Choosing a Fluid Flow Program

PEW

Design Calculations

Which Fluid Flow

Program?

PIPER FLONET ADRIAN

Rating Calculations

Two Phase Liquid Gas

Non Ideal Near Ideal

Low

Ma < 0.2

High

Ma > 0.2



Appendix C – Vessel Calibration

This appendix discusses the types of calibration data required for horizontal, vertical and inclined

vessels.

Appendix C.1 – General Data for Horizontal or Vertical Vessels

Note. All dimensions are vessel internal dimensions.

Figure 18 Vertical Tank with a Dished and Conical End

The total length of the vessel, including the ends or the cylinder length (the central cylindrical

portion) can be supplied.

The diameter of the central cylinder is required.

The density of the liquid or solid in the tank is used to relate the mass and volume calibrations.

The height of top end of cylinder is only required for inclined tanks, and is the height of the

top end of the cylinder above the bottom end of the cylinder.

Cylindrical

Length

Cylinder Diameter

Radius

of

Dish

Transition

Knuckle

Radius

Distance from cylinder

to end of cone

Overall

Tank

Length

END2

END1

D



Appendix C.2 – General Data for Inclined Vessels

Inclined Vessel: Height (H) of Upper End above the Base (see Figure 19).

Figure 19 Inclined Vessel

The orientation of the axis of the central cylinder can be horizontal, vertical or inclined.

The sine of the angle of elevation is height/cylinder length H/L. If the angle is known but not

the height, the height can be calculated from:

Height = Length x sin ()

H

L

θ



Appendix C.3 – Input Data

End Dimensions

Each end of the cylinder can be:

Flat The straight across the end of the cylinder.

Conical A cone with a rounded end linked to the main cylinder by a transition knuckle.

Ellipsoidal An elliptical end with no transition knuckle.

Dished A rounded end linked to the main cylinder by a transition knuckle.

The diameter of the small end is only required for conical ends and is the diameter of the

rounded end of the cone shown as „D‟ in Figure 18.

The cylinder end distance is the distance from the end of the cylindrical portion of the vessel

to the end of the cone it is only required for conical ends.

The dished end radius or minor axis is required for ellipsoidal and dished ends and has

different meanings as follows:

Ellipsoidal The minor radius of the ellipse.

Dished The radius of the dished end.

The radius of the transition knuckle is required for conical or dished ends which are assumed to

be joined smoothly to the main cylinder by a curved transition knuckle.

Calibration

The vessel can be calibrated for the volume, mass or depth of contents.

The calibration points can be specified as follows:

Select the number of points to be calibrated up to a maximum of 20 and the increment size is

calculated by the program to cover the whole vessel.

Specify an increment size. The program calculates increments starting at the base of the vessel

until the whole vessel is calibrated or 20 points are reached. If the increment size is too small

to calculate the whole vessel, a warning message is given and the final point gives the values

when the vessel is full.

The program can also calibrate to given points. Set the number of points required up to a

maximum of 10 and supply each point in the given points fields. This allows uneven spacing

of the calibration points.



Appendix C.4 – Calculation Method

The tank is divided into up to five sections - the cylinder, the two ends and (if appropriate) the two

transition knuckles. Using explicit equations, the program starts by calculating the relationship

between the cylinder length and the overall length, fixing the value that the user has not provided.

The vessel wall surface areas of each constituent part of the vessel are calculated from explicit

geometric equations as a function of depth and angle of inclination. The volume of that section is

then calculated by multiplying by the height of the section.

If the user has fixed the mass or volume then the depth is calculated explicitly. However, if the

user has fixed the depth the resultant volume and mass increments are calculated iteratively.

Appendix C.5 – Possible Errors in the Calculation

The correlations for surface area used are rigorous descriptions of the geometric shapes involved.

Errors may appear in the integration and the iteration but these are very small (less than 0.1%).

The most likely source of error is unrealistic input.

The program does not perform the calculation and prints warning messages if any of the following

conditions apply:

The transition knuckle radius is too big for the cone or dished end.

The radius of the dished end is less than the tank diameter.

The height of the upper end of the cylinder is greater than the cylinder length for an inclined

vessel.

There are also various other possible input errors which are impossible to trap out such as too big,

too small increments, increment units etc.

The program may indicate that it cannot calculate the top increment in a tank and has reduced the

last calculated value accordingly. This could be within the programs convergence limits and any

error is less than 0.1%.



Notes Use this page to record any notes.