Objective

• Address your concerns/suggestions• Review

• Learn about Cooling Systems • Compressor cooling circles

• Sorption coiling

• Evaporative cooling

Vapor Compression Cycle

Expansion valve

Outdoor 105°FIndoor 75°F

Thermodynamics - review

Thermodynamics - review

Thermodynamics - review

• Enthalpy: h [J/kg, Btu/lb]• Temperature change ΔT

Δh = cp ΔT – only for the same phase (air, water)

What if we have change of the phase -evaporation or condensation?

• Entropy: s [J/kgK, Btu/lb°F] Δh = T Δs for evaporation or condensation

What is the COP?

A. Congressional Observer Publications

B. California Offset Printers, Inc

C. Coefficient of Performance

D. Slang for a policeman

COPCoefficient of Performance

[W]energy electric Used

[W]energy cooling ProvidedCOP

Refrigeration Cycle

Components of a DX system

• Compressor

• Evaporator

• Condenser

• Expansion valve

92 °F

56 °F69 psig

DB = 77 °FWB = 64 °F

orificecapillary tube

TXV

110 °F~200 psig

DB = 60 °FWB = 53 °F

High pressure, high boiling/condensing point

Low pressure, low boiling point

DX Cooling Machine

Air Cooled Chiller

Outside air 95°F

Inside 75°FWater 42°F

BuildingWater 52°F

Chiller

Water Cooled Chiller

Outside air 95°F

Inside 75°FWater 42°F

BuildingWater 52°FWater 120°F

Water 100°F

Cooling tower

Chiller

Cooling

Evaporative cooling Compressor Cooling Sorption cooling

DX machine Chiller

Air CooledCondenser

Water CooledCondenser

Convert Cooling machine (DX machine) to heat pumps

Evaporative Chiller

Air cooled condenser

• Only for small capacity

• Cool the water or directly the refrigerant for compressor chillers

Cooling tower

• Provide cooling water for condenser or absorption

Type

Location Legionella

Evaporative Cooling

• Wet media/water spray – direct• Raise absolute humidity, lowers temperature of

conditioned air

• Cooling tower – indirect• Cools through a heat exchanger• Lowers temperature, does not affect absolute

humidity• Can directly cool air in cold weather

Evaporative Cooling

What is Heat Pump ?

Cooling Heating

Outside 95°F Outside 55°F

Inside 75°FInside 75°F

www.srpnet.com/energy/pumpworks.aspx

1) Compressor

2) Condenser

3) Evaporator

4) Air handler

5) Reversing valve

and expansion valve

COP for heat pump

energy electric Used

energy electric Usedcondenser on Cooling HeatingCOP

[W]energy electric Used

[W]energy heatin ProvidedHeatingCOP

energy electric Usedcondenser on Cooling energy heatin Provided

energy electric Used

energy electric Used

energy electric Used

condenser on Cooling HeatingCOP

1 CoolingHeating CPOCOP

Energy Storage Systems

Daily distribution of cooling load

Thermal Storage

• Make ice/chilled water at times of low demand or low energy prices

• Store water in insulated container

• Can be used to reduce overall demand

• Water can be used as secondary water source for fire protection

• Ice/snow

Thermal Storage

Reading Assignment

Tao and Janis Chapter 4