Air Conditioning System − 2 Created by: David Chadderton Email: dchadder@ncable.net.au 8 November 2018
Packaged Room Air Conditioner and Evaporative Cooling Principal Operation 8 November 2018
Packaged air conditioning − RAC Through the wall room air conditioner used in small rooms, offices, workshops, motel rooms and homes. Noisy. Reverse cycle heat pump. Same as car air conditioning system. Same as refrigerator operation. Hermetically sealed refrigerant reciprocating piston compressor and electric motor, scrapped on failure. 8 November 2018
8 November 2018
8 November 2018
8 November 2018
8 November 2018
8 November 2018
Condenser, cools and liquefies the refrigerant at 40oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC 8 November 2018
Hot high pressure gas, 50oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC Warm liquid high pressure, 30oC 8 November 2018
Condenser, cools and liquefies the refrigerant at 40oC Hot high pressure gas, 50oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC Outside air, 0oC to 40oC Warm liquid high pressure, 30oC 8 November 2018
Condenser, cools and liquefies the refrigerant at 40oC Heat absorption Hot high pressure gas, 50oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC Heat absorption Evaporator, boils the liquid the refrigerant at 5oC Outside air, 0oC to 40oC Low pressure liquid and flash vapour, 5oC Warm liquid high pressure, 30oC 8 November 2018
Condenser, cools and liquefies the refrigerant at 40oC Heat absorption Hot high pressure gas, 50oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC Heat absorption Evaporator, boils the liquid the refrigerant at 5oC Cooling coil in air conditioning Outside air, 0oC to 40oC Warm liquid high pressure, 30oC Low pressure liquid and flash vapour, 5oC 8 November 2018
Cold low pressure vapour, 5oC Hot high pressure gas, 50oC Heat rejection Condenser, cools and liquefies the refrigerant at 40oC Heat absorption Evaporator, boils the liquid the refrigerant at 5oC Cooling coil in air conditioning Outside air, 0oC to 40oC Warm liquid high pressure, 30oC Low pressure liquid and flash vapour, 5oC 8 November 2018
Ground Source/Sink Heat Pump Condenser Underground In-ground plastic pipe coils to reject heat from the air conditioning system refrigerant condenser. This replaces the use of a cooling tower. No maintenance requirement. Running cost of only one pump, same as with a cooling tower, but minus the cooling tower fan and water treatment chemicals. Can be suitable for small buildings on well-drained sloping grassland by a river to ensure heat removal from the soil. 8 November 2018
Evaporative Cooling Directly evaporating mains cold water within a ventilated air handling unit is used in hot dry climates such as southern Australia where the atmospheric humidity is usually in the range of 20% to 40% year round, unless it is actually raining. (This is not very often!) It is the same principal as used by a cooling tower, except that air is the medium being cooled. This is the air breathed within the building. Characteristics of individual units and ducted systems: Very low energy use Low water consumption High air change rate − up to 60 per hour, one a minute Noticeable high air flow Can be noisy Individual units on roof Ducted systems Indoor air becomes more humid − 70%, noticeable Low cost Highly effective Minimal maintenance 8 November 2018
Ducted, roof mounted direct contact evaporative cooler Water spreader Mains cold water Supply air duct to room passing humid cooled air Filter material Hot dry external air, 30oC+ and 25% percentage saturation Axial fan Overflow from water tank 8 November 2018
End 8 November 2018