Cellulose pad, Evaporative cooling, air-conditioning system, condenser, Coefficient of performance
This paper presents an experimental investigation of the application of direct evaporative cooling to reduce energy consumption in a residential sized split Air-Conditioning system. Direct evaporative cooling is employed at the air-cooled condenser of a split air-conditioning system to pre-cool the ambient air flowing over the condenser coils. Different ambient conditions of air were simulated using a heater to mimic typical high temperature environments. Rigid cellulose pads with thickness ranging from 2-6inches (5.1cm-15.24cm) served as the heat exchange medium for air-water interaction, and were tested to determine the influence of the pad thickness in pre-cooling the ambient air before it flows over the condenser coils to extract heat from the refrigerant in the condenser. It was observed that a 10C drop in ambient air temperature causes the condensing temperature of the refrigerant to drop by 0.60C. This drop in condensing temperature of the refrigerant causes a decrease in power consumption of the unit, accompanied by an increase in Coefficient of Performance (COP). Results obtained shows that up to 44% increase in COP, and a 20% decrease in power consumption can be achieved by employing evaporative cooling. Additionally, the COP was found to increase by 4% for every 10C drop in refrigerant condensing temperature. The water consumption pattern of the hybrid system is monitored to provide a realistic estimate of the operating cost, and profitability of the hybrid system. It was observed that 0.34liters of water is consumed for every percent increase in COP. To provide a realistic estimate of the daily water consumption of the hybrid system, the operation time was increased from 1-4hours, in step increments of 1hour. The volume of water consumed was found to increase by a factor of 1.8, 2.5, and 3.2, for 2hrs, 3hrs and 4hrs of operation respectively. This shows that as the operating hours of the hybrid system in a day increases, the volume of water consumed will decrease.