Course project presentation

• Thursday in class

• Timing: 4 minutes (strictly controlled)• Approximately 1 PowerPoint Slides per minute

Content • Problem Introduction • Methodology • Results • Comments and recommendation

• You need to email me your presentation before the class!

• 2 minutes for Question and Answers

Final project report

• Introduction

• Methodology

• Results

• Comments

• DO NOT submit pictures without comments

• Analyze the result - create diagrams and tables

Objectives

• Finish control systems – sequence of operation • Psychrometric chart

• Learn about desiccant systems • Psychrometric chart

• Learn about software for load calculation

• Review

HVAC ControlExample 2:

Dew point control (Relative Humidity control)filter

fancooling

coil

heating

coil

filter

mixing

damper fresh

air

T & RH sensors

We either measure Dew Point directly or T & RH sensors substitute dew point sensor

Humidity generationHeat gains

We should supply air with lower humidity ratio (w) and lower temperature

Relative humidity control by cooling coil

»TDP

Mixture

Cooling Coil

RoomSupply

»Heating coil

Relative humidity control by cooling coil (CC)• Cooling coil is controlled by TDP set-point

if TDP measured > TDP set-point → send the signal to open more the CC valve

if TDP measured < TDP set-point → send the signal to close more the CC valve

cooling

coil

heating

coil

»mixing

Fresh air

Tair & TDP sensors

Control valves

• Heating coil is controlled by Tair set-point

if Tair < Tair set-point → send the signal to open more the heating coil valve if Tair > Tair set-point → send the signal to close more the heating coil valve

Sequence of operation(ECJ research facility)

»Control logic:

»Mixture in zone 1: IF (( TM<TSP) & (DPTM<DPTSP) ) heating and humidifying

»Heater control: IF (TSP>TSA) increase heating or IF (TSP<TSA) decrease heating

»Humidifier: IF (DPTSP>DPTSA) increase humidifying or IF (DPTSP<DPTSA) decrease humid.

»Mixture in zone 2: IF ((TM>TSP) & (DPTM<DPTSP) ) cooling and humidifying

»Cool. coil cont.: IF (TSP<TSA) increase cooling or IF (TSP>TSA) decrease cooling

»Humidifier: IF (DPTSP>DPTSA) increase humidifying or IF (DPTSP<DPTSA) decrease hum.

»Mixture in zone 3: IF ((DPTM>DPTSP) ) cooling/dehumidifying and reheatin

»Cool. coil cont.: IF (DPTSP>DPTSA) increase cooling or IF (DPTSP<DPTSA) decrease cooling

»Heater control: IF (TSP>TSA) increase heating or IF (TSP<TSA) decrease heating

Set Point (SP)

Mixture 2

Mixture 3

Mixture 1

»DBTSP

DPTSP

Sensible and Enthalpy and Desiccant wheels

Desiccant wheel

»Figure 3 – A desiccant-based cooling system combined with regenerative heat exchanger, vapor compression cooling, and evaporative

humidifier (hybrid system).

Computer software for load calculation

• http://www.xpedio.carrier.com/idc/groups/public/documents/marketing/hap_ehelp_009.pdf

• http://www.doe2.com/equest/

• http://tc47.ashraetcs.org/pdf/Presentations/Liesen_Chicago.pdf

Residential vs. Commercial systems

• Course focus was on HVAC equipment that is used in both: residential and commercial systems

• Emphasize on the application in commercial systems

Commercial HVAC Systems

Single zone Multi zone

VAVCAV VAV CAVAll Hydroinicthat relay on infiltration

With and without reheaters

DOAS with fan coilsor radiant ceilings

With reheaters

Dual duct

Dual duct DOAS with

fan coils

With and without humiditycontrol

This is not the complete list !

Typical Components in Commercial systems

• Constant operation

• Outdoor air supply

• Two fans (supply and return)

• Multizone system

• Control

• …..

Residential System

Course objectives• Apply fundamental physical principles to HVAC

design• Describe and size each component in an HVAC

system• Design HVAC systems based on manufacturer’s

datasheets• Contrast residential systems with commercial

systems and use appropriate design techniques for each type of system

• Solve HVAC design problems with high-quality references