Objective Learn about Cooling and Cooling systems Define heat pump Learn about energy storage systems

Refrigeration Cycle

92 °F 56 °F 69 psig DB = 77 °F WB = 64 °F orifice capillary tube TXV 110 °F ~200 psig DB = 60 °F WB = 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°F Water 42°F Building Water 52°F Chiller

Water Cooled Chiller Outside air 95°F Inside 75°F Water 42°F Building Water 52°FWater 120°F Water 100°F Cooling tower Chiller

Cooling Evaporative cooling Compressor Cooling Sorption cooling DX machine Chiller Air Cooled Condenser Water Cooled Condenser 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 Water need some treatment - Legionella !

What is Heat Pump ? Cooling Heating Outside 95°F Outside 55°F Inside 75°F

COP for heat pump

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 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 Cycle Strong 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 Cooled Condenser Water Cooled Condenser 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