Testing of a cold thermal storage classroom air conditioning system equipped with occupancy sensors

A Kolin window type air conditioner model KAG-19ME installed in a classroom was equipped with a cold water thermal storage system controlled via occupancy sensors. The cold thermal storage system consisted of a 150 liter water tank with three partitions connected by weirs, one for the returning warm water, one for the cold water settling, and one for the cold water used for the releasing phase. The water is cooled, in the charging period, in the evaporator during periods when the air conditioning load is low. The cold water is used, during the releasing phase, to supercool the liquid from the condenser prior to throttling to the evaporator. The flow of water in and out of the storage tank is controlled by two pumps which is in turn controlled through occupancy sensor input. Two heat exchangers were used, one to supercool the refrigerant after the condenser, and the other to cool the water that will be stored inside the cold storage tank.Initial tests show an increase in the coefficient of performance of the air conditioning system, however, energy consumption is not mitigated because of additional consumption by the pumps.