Objectives

• Finish duct systems

• Learn about plumbing systems

• Discuss your question relate to HW4

• Introduce some project topics

VAV Operation

How to use multiple pumps

Dampers

Summary of Air Distribution Systems

• Select diffuser based on ADPI

• Given a layout of duct system• Calculate total pressure drop• Deal with non-circular ducts and fitting losses

• Select the fan based on fan and duct curve

Hydronic Terms

• Head loss

• Open-loop vs. closed loop

Head Loss

Fittings

g

Vkh

2

2

Pumps

• Driving force to move air water in buildings

• Raise pressure and produce flow

• One main type• Centrifugal

Pump curves

• NPSHR = Net Positive Suction Head Required

Plumbing Arrangements

Project

• Design problem• ….

• Research problem• ….

Cooling tower

TCWRTCWS

TCTS TCTR

Q

P

- Find COPfor several weather condition

-Use nonlinear equation solution methods

Weather parameters

Couple chiller and cooling tower

HVAC ControlEconomizer (fresh air volume flow rate control)

filterfan

cooling coil

heating coil

filter steamhumidifier

mixing

damper fresh air

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 heatingHumidifier: 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

coolingHumidifier: IF (DPTSP>DPTSA) increase humidifying or IF (DPTSP<DPTSA)

decrease hum.

Mixture in zone 3: IF ((DPTM>DPTSP) ) cooling/dehumidifying and reheatinCool. 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

Return

In-Take air

Exhaust

Supply

Fan

Ducts

Biomedical Engineering (BME) Building

Duct Optimization

Life Cycle Cost Analysis• Engineering economics

Option A

Option B

Enthalpy wheel

VAV Example

»http://www.trane.com/commercial/library/vol242/v24b6.asp

-One system

-Multiple Spaces/Zones

- VAV box for each space/zone