Post on 01-Jan-2016
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