Humidification Overview

Dave Bennett

Regional Sales Manager

Why Humidify

Properly Controlled Humidification:

• Enhances Occupant Health and Comfort

• Improves Manufacturing Processes

• Helps Preserve Building Materials and

Furnishings

Cost for Humidification is Easily Offset by:

• Gains in Life of Materials

• Process Effectiveness

• Increased Productivity & Quality

• Occupant Vitality and Satisfaction

Humidification Applications

3

Area of focus Reasons to humidify

Hospitals

Surgical suites

Labs

MRI suites

Burn wards

Neonatal

Pharmacies

Safety

Codes and regulations

Product preservation - medications

Infection control

Proper equipment operation

Healing

Universities

General laboratories

Animal laboratories

Research facilities

Server rooms

Libraries

Process integrity

Proper equipment operation

Preservation

Pharmaceuticals

Manufacturing

Research laboratories

Server rooms

Product storage

Process integrity

Product preservation

Codes and regulations

Manufacturing

Wafer fab

Electronic

Aviation

Printing plants

Clean rooms

Process integrity

Static control

Evaporative cooling

MuseumsExhibition areas

Storage areasArt and artifact preservation

Terms - Relative Humidity

THE ACTUAL AMOUNT OF WATER VAPOR IN THE AIR COMPARED

TO THE MAXIMUM IT CAN HOLD AT ANY GIVEN TEMPERATURE

PERCENT

RELATIVE

HUMIDITY

SATURATION CURVE

(100% RH)

Terms - Relative Humidity

30 ºF

70 ºF

Relative Humidity is a term used to describe the actual amount of water vapor in the air as a percentage of the maximum amount of water vapor which the air could hold at a given temperature.

18% RH

80% RHNOTE:

The absolute

amount of

water vapor

stays constant

at 19 Grs/Lb

Dispersion Panel

Steam injection multi-tube

Steam injection single tube

Terms - Absorption distance

Absorption distance varies

based on incoming Temp

and RH as well as

dispersion type

Terms - Atmospheric Generators

When the system is first activated, the fill valve opens and the evaporating chamber fills with water to the

operating level.

On a call for humidity, the heating elements are energized,

causing the water to boil. The fill valve opens and

closes as needed to maintain the operating

water level.

During refill in tap/softened water systems,

a portion of the surface water is skimmed

off, carrying away precipitated minerals.

Systems with the RO/DI water option (using

deionized water or water that has been

treated using reverse osmosis) do not

require skimming.

Steam created in the evaporating chamber

flows through steam hose, tubing, or piping

to the dispersion assembly, where it is

discharged into the airstream.

HumidificationComponents

Typical humidification system

Steam Generator

or Steam Boiler

Steam Piping

Steam Dispersion

10

Humidifier placement

11

Humidifier placement

Types of Humidification

1/29/2019 12

ISOTHERMAL

Isothermal means occurring at

constant temperature.

In the isothermal process, water is

boiled from a heat source and the

and the resulting steam is added to

the air.

The isothermal process can warm the

air by up to several degrees. This is

due to the temperature difference

between the and the temperature of

the steam.

ADIABATIC

In the adiabatic process, all of the heat for evaporation is taken from the air itself. On the psychrometric chart, this process follows the wet bulb line.

As the process moves up and down the wet bulb line, the RH and the air temperature are both changing, but the total heat content remains unchanged.

Stated another way, the air temperature is lowered and the humidity is increased by a simple transfer of heat from the air to the water as it evaporates.

Types of Humidification Systems

Adiabatic

Pressurized Water

Wetted Media

1/29/2019 Confidential 13

Isothermal

Pressurized

• Steam from boilers or district plants

Atmospheric/Non-Pressurized

• Steam generators by humidifier supplier

Isothermal - Single-tube steam jacketed

Isothermal - Single-tube steam jacketed

Isothermal - Single-tube steam jacketed

Isothermal - Single-tube steam jacketed

Isothermal - Pressurized Steam Jacketed

Isothermal – Dispersion Panel

Drain Tempering

• Water tempering device.

• Mixes cold water with hot condensate

discharged from steam humidification

equipment to reduce the discharged water

temperature.

• Most municipalities prohibit draining

water hotter than 140˚F (60˚C) into

their sewer systems.

• PVC drain pipes are susceptible to

damage from water that is too hot.

AdiabaticEvap Cooling &

Humidification Systems

Direct or indirect evaporative cooling

Indirect evaporative cooling occurs in the heat exchanger without adding moisture.

Direct evaporative cooling and humidification adds moisture to the supply air.

Heat exchanger with bypass

dampers (both airstreams)

Final evaporation media

DispersionFilter

DispersionFilter

Heating coil

Final evaporation media

Cooling coil

Conditions*Blue = Indirect cooling

Red = Directcooling

Black = With humidification

*Typical conditions

Wetted Media Systems

Wetted media benefits

Energy efficient cooling

Low maintenance

Simple, reliable systems

LEED credits and utility rebates

Lowest first cost

High-Pressure Atomization Systems

What is a high-pressure system?

Disperses mineral-free water at high-pressure into air

Adiabatic process affects both temperature and RH

High-pressure water through specially-designed nozzle orifice breaks into

ultra-fine droplets to maximize evaporation

90% are 10 microns or less, maximizing evaporation (average human hair = 40 microns)

Ultra-fine droplets

Atomization System components

12

34

5

6

7

2. Duplex water softener

3. RO station & holding tank

4. High-pressure pump station

5. Zone control cabinet

7. Dispersion into the air

6. Solenoid valves turn on

1. Supply water to dechlorinator

1 2

3

4

5

6

Water Quality and Treatment Systems

29

Humidifiers and water type

Four types of water used in humidifiers

• Potable water

• Softened water

• Reverse osmosis water

• Deionized water

Do not use

Well Water!

Water Properties

• Grains of Hardness

o Measure of water hardness

o 17.1 ppm = 1 grain hardness

• Total Dissolved Solids (TDS)o All substances that are dissolved in the water

o Principal TDS contributors: calcium and magnesium

carbonates and bicarbonates (principal scale forming

substances) among others

• pHo pH is a measure of the acid or base levels of the water

� Range is 0 – 14; 7 is neutral

• Chlorides (not chlorine)o Main corrosion mechanism in stainless steels is chloride

stress corrosion cracking

o Chlorine gains a negative charge when dissolved in water

o Remains in the tank and concentrates as water is boiled off

30

31

Softened water

• Ion exchange process – calcium replaced by sodium

• Dramatically improves humidifier performance and

efficiency

• Extend maintenance intervals

from yearly to every 3 years

with softening alone

• Soften if water hardness

exceeds 12 grains

32

Reverse osmosis water

• Water is softened and cycled through a reverse

osmosis permeable membrane

• 97% of total dissolved

solids (TDS) are

removed

Dechlorinator

These are important to protect your RO

membranes. RO membranes can be

destroyed by Chlorine.

34

De-ionized water

Deionization is a chemical process that uses specially

manufactured ion-exchange resins, which exchange

hydrogen and hydroxide ions for dissolved minerals,

and then recombine to form water. Deionization

produces highly pure water, with the advantage that

the process is quicker and does not build up scale.

Deionization does not significantly remove uncharged

organic molecules, viruses or bacteria.

Water treatment systems example

Dechlorinator

Water Softener

Reverse Osmosis

Project Design

What you need to start a job

�Entering and leaving conditions

(CFM, air temp, OA% and RH)

�Water Quality Test

�Absorption distance

�Humidification load

�Consider Maintenance Needs

�Humidification Accuracy Required

�Determine Steam Source

�Plan for Control System

Interoperability

Water Testing

Ultra-sorb XV

Steam injection multi-tube

Steam injection single tube

Absorption distance comparison

Guaranteed short absorption distance in inches

40

Your Local Rep can be very helpful!

Load Calculation

41

• Water with low mineral content means low

maintenance

• Hard water affects energy efficiency – more

wasted water to remove minerals

• Clean water ensures performance

Maintenance

Reduce Humidifier Maintenance With Softening or RO

42

• Hard water forms scale and

needs cleaning with chemicals

or mechanical removal of

solids

• Water softeners extend

maintenance intervals by a

factor of three

1/29/2019

• Reverse osmosis systems uses

easy-to-replace parts and may

eliminate humidifier

maintenance

Poor Maintenance = Down time and Service Costs

Efficiency of heat exchanger reduced

After cleaning

Application/Design Concerns

Typical Application/Design concerns

�Steam Piping Layout

�Water quality vs Maintenance

�Condensate Management

�Control Sequence

�Redundancy

�Air velocities (200-3000 FPM is

typical)

Piping

Steam Traps and Water Seals

Condensate Management

Condensate Management

Condensate management

53

�Condensate drains, pumps, and

Steam Traps

�Maintenance Access (access

doors are a good idea)

�Keep away from Duct Transitions

Considerations for Locating the Steam Dispersion

HumidificationControls

Control

Generators typically come with an integral controller

Why is an integral controller important?

• Performs water level controlo Fill/drain

• Regulates steam output

• Allows for diagnostics

• Allows for connection to building automation systems

Typical Field Installed Controls• RH sensor (duct or room)

• RH High Limit (on/off or modulating)

• Air Flow Switch (sail or pressure)

Water Level Controls

Hard or Softened Water RO or DI Water

Output Control Options

• On-off

• Time proportioning/ modulating control

• Fully modulating – SSR, SCR, valves with high

turndown ratio 50 to 1

• For Gas Models you can find 5:1 modulation

Tight control requires RO or DI

water

Step 6: Define Humidifier Accuracy• Good Strategies are based on air changes per hour

and RH accuracy requirement

• Discharge Air Humidity Control does not work

• Averaging several humidity sensors leads to unhappy sensors

• Sensor accuracy and sequence must be built to meet project demands.

• Equipment type affects accuracy

• Make up water type affects accuracy

• Supply air temp changes affect accuracy

• 1 degree F change is a 3% move in RH%

Control System Considerations

Humidifier Accuracy Example

+/- 1% accuracy with high number of air changes is possible,

provided:

• Temperature must stay within +/- 0.2F

Pressurized steam controlled by industrial steam valve with

adequate turndown

Resistive electric humidifier with DI/RO water and SSR controller-

NOT ELECTRODE TYPE

Typical projects allow for a 5-10% swing in humidification setpoint

Gas heat exchanger humidifiers may have limitations due to

modulating gas valve limitation and purge times

Control System Consideration

Control Application Examples –

• Low air temp/humidity control for surgical suite –

(Return air sensors, HEPA filter vs grid

placement/Absorption distance)

• 100% OA unit control –

(reheat, VAV operation affects on Absorption

Distance)

• Every Day Comfort – Humidistat and airflow switch

Control System Consideration

• Sensor placement – Make sure you capture all

your rooms on a VAV system

• Leaving Dispersion RH% vs the modulating duct

high limit set point difference

• BAS vs Local system output control

• BAS may require tuning to remove hunting

Sensor Placement

63

64

Spec items to pay attention to

�Maintenance – use manufacturers

recommendations

�Start up – ask that they submit a report for

record and use manufacturer recommendations

�Water Testing – consider having a water test

before final selection when possible. Add in

periodic testing to correct issue ahead of time.

�Specify Max Available Absorption distances

�Specify Heat Gain

�Piping details – show traps and dimensions

please.

�Don’t forget your Drain coolers

Three major dispersion tube technologies

R-value = 0.045 R-value = 0.16 R-value = 0.56

Thermal coating Steel w/ air gap* PVDF

Higher R-value = Higher energy and water savings *Steel with air gap tube uses thin PVDF strips to reduce heat conduction between tube and shield

Delivers 2 to 3.5 times the energy savings

Specify Heat Gain

Thermal Insulating

coating 0.030” thick

Stainless Steel

dispersion tubeAir gap. Width

ranges from 0” to 0.25”

PVDF strip

Stainless

Steel shield

Stainless Steel

dispersion tube

Stainless Steel

dispersion tube

PVDF Insulation

0.125” thick

Piping Details

Piping Details

Clean Steam

69

Clean Steam

• Scrutinize use in hospitals or museums

• Steam boilers with condensate return must

protect piping with dangerous chemicals

Sodium Sulfite, Sodium Hydroxide, Sodium

Gluconate

• Chemicals in steam used for humidification

will enter AHU air stream

• Steam to Steam units are available to

provide clean steam when needed

70

71

Pit Falls of designs

�Set point Sensor placement

�Control System Specifications and

Sequence

�Absorption distances Creeping

�Maintenance Access = Maintenance

Performed

�Piping Layout

�Electrode vs Resistive

About electrode humidifiers

Electrode Unit Principle of operation

Uses electrode probes

and the conductivity of

water to boil the water

instead of resistive

elements

XT Operation

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120 140

Seconds

Current

Current

Electrode Unit Start up

+/- 10%Settles in

at ~2/3

bottle

height

Nominal current

Water hits electrodes

Fill valve opens (current increase w/ more electrode covered)

Electrode Unit considerations for water

Check your conductivity before installing

• Levels over 400 micro semens work best

• Softened Water can cause high conductivity and increase cylinder replacement

Hard water works best

• Scale precipitates out and eventually fills the cylinder, reducing its output

76

Summary

• Test Your Water

• Add softeners to reduce maintenance and improve

performance

• Accuracy is affected by temp change, controls,

and steam source

• Specify Heat Gain

• Detail Piping Pitch, Steam Traps, and Drains

• Keep controls local when possible

QuestionsPDH Questions

PDH Questions

1/29/2019 78

Q1: Where is the best place to put a steam dispersion device?

Q2: Does the water type supplied to a humidifier affect the design?

Q3: Do you need water testing before selecting a humidifier?

Q4: What is the most accurate and quick responding humidification

system?

Thank you for you time!