A Novel Technique for Reducing Cooling Load of an Air Conditioning System Operating in Hot and Humid Climates

Cooling load is the energy needed to be removed from a space by a cooling system to provide the desired level of comfort. Large space load requires high energy from the cooling system. A new technique of reducing the cooling load using condensate to pre-cool air stream entering the evaporator of a vapor compression air-conditioning system is presented in this paper. In a cooling process, water vapor condensation normally occurs when the evaporator coil surface temperature becomes lower than the dew point temperature of the humid air entering the evaporator. The cooling process results in appreciable amount of condensate in climatic conditions with high relative humidity and temperature such as those in Dhahran, Saudi Arabia. The rate of condensate yield is calculated using actual climate data of three typical summer days of Dhahran area for the months of June, July and August. These months are the most humid and hottest during the year. Each month is represented by a typical day determined by the average of the three hottest and humid days during the same months of the past three years. It is found that the condensate obtained during night time is more than the day time because of the high relative humidity at night. The results indicate that the cooling load can be reduced up to 10 % when the air entering the evaporator is pre-cooled by 4 °C using the condensate. In addition, the daily condensate yields from the evaporator coil in June, July and August are 1.27, 0.92 and 1.31 kg/kW-CDD, respectively.