Objective

• Learn about Cooling and Cooling systems • Define heat pump

• Learn about energy storage systems

Refrigeration Cycle

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

LocationWater need some treatment - Legionella !

What is Heat Pump ?

Cooling Heating

Outside 95°F Outside 55°F

Inside 75°FInside 75°F

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

www.srpnet.com/energy/pumpworks.aspx

1) Compressor

2) Condenser

3) Evaporator

4) Air handler

5) Reversing valve

and expansion valve

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

Can you use the steam for cooling?

A Yes

B No

Absorption Cycle

• Water is typical refrigerant• Strong vacuum - ~0.116 psi or 0.0008 MPa• Boiling point of water?

• Differences from vapor compression• No compressor

• Chemical (e.g. LiBr - hygroscopic) – Absorbs water vapor turns it into a liquid

– Regenerated by removing water

• Requires heat

Absorption CycleStrong vacuum Refrigerant: water Absorber: lithium bromide

Replace compressor

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

Cooling

Evaporative cooling Compressor Cooling Sorption cooling

DX machine Chiller

Air CooledCondenser

Water CooledCondenser

Convert Cooling machine (DX machine) to heat pumps

Evaporative Chiller

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 - whole Chapter 4