The Effect of Increasing Sub-Cooling on Air-Cooled A/C System's Capacity

Abstract

The present research covers the effect of adding an extra water-cooled condenser in series with the main vapor compression refrigeration system as a heat sink source for system sub-cooling. An experimental laboratory study has been done on a split unit air conditioner with a (24000 Btu/hr) nominal capacity, taking into consideration the effect of outdoor ambient temperature and cooling load. A high accuracy fully instrumented experimental rig interfaced with a computer has been constructed, specially designed for refrigerant R22, using a capillary tube with a size chosen according to ASHRAE to control the refrigerant mass flow rate. The extra refrigerant sub-cooling temperature difference was between TSC= 5 oC and 10^oC, this value was chosen in order to not exceed the limits of the original system sub-cooling. The experimental results show that there is an increase in the system capacity by +1.37% to +7.065% when TSC= 5 oC, for ambient temperature between Tamb=30 oC and 46^oC, and +4.1% to +14.13% when TSC= 10^oC for the same previous Tamb. The power consumed per ton of refrigeration shows a decrease by -0.948% to -3.417% for TSC= 5^oC, and -2.84% to -7.745% for TSC= 10 oC for the same ambient temperature previously mentioned......