Lecture Objectives: Continue with air-conditioning (psychrometric) by looking into swimming pool example homework assignment problems Look at the cooling side of air condition solve some problems related to the cooling system efficiency

Heat pump example A recreation center Heat Pump Ice Rink Swimming pool Condenser Evaporator 85-89oF 30oF Consumes heat energy Rejects heat energy Electric power for a compressor

Swimming pool energy and mass balance

Evaporation Heat loss by evaporation: hm Tpool Tair pool W s W ≈ hm Ws Tpool Wair pool Depends on the air speed and even more on the condition of the water surface (people splashing in the water) Further analysis can be conducted in the psychrometric chart

Air conditioning in Air Handling Units (AHU) Fresh (outdoor) air Cooling coil Heating coil damper Fan (pull) Fan (push) mixing Recirc. air Filter Swimming pool

Air Handling Unit (AHU) Configurations

HW Assignment Textbook (Thermal Environmental Engineering) problems: 8.1, 8.8, 8.13, 8.20 Need to talk about: - humidification and - heat recovery

Humidification (steam or air washer) Steam humidifier Air washer (mister)

Cooling Cycle (we discussed this but we need some numerical examples) We need: COP = (h3-h2)/(h4-h3)

T-S diagram (water)

P-h Diagram (water)

P-h Diagram for R22

Example A) Calculate the COP when: ambient temperature is 30ºC Cooling coil (CC) is 10ºC Assume that : condensation is 10ºC above ambient temperature and evaporation is 10ºC below CC temperature B) How much electricity you need to provide 1 ton of cooling ?