A development of a portable air conditioning-heat pump unit using helical coil heat exchanger

In the present energy crisis situation, maximization utilization of energy use is vital matter, especially an air conditioning unit which is one of the largest energy use in the home. The objectives of this paper are to: i) design and development of a portable air conditioning:-heat pump unit using helical coil heat exchanger, ii) improve the cooling performance of a portable air-conditioning heat pump unit, iii) enhance the heat recovery performance of the heat recovery system, and iv) improve the energy efficiency of the portable water-cooled air conditioning unit. In this research, a heat exchanger designed, working as water cooled condenser, consists of a shell and helically coiled tube unit which is fabricated by bending a 9.50 mm diameter straight copper tube into a helical-coil tube of twenty turns. Water and refrigerant R-22 are used as working fluids in shell side and tube side, respectively. The operation test results of the designed portable air conditioning-heat pump unit using helical coil heat exchanger, found that the unit worked satisfactorily. This paper then investigated the benefits of applying a helical coil heat exchanger for heat recovery of a portable air conditioning-heat pump unit. The unit with heat recovery system was set up for study at various water flow rates. The cooling performance, the heat recovery, and the energy consumption for different warm water flow rates were measured. The results show that the experimental unit when heat up the water by approximately 15-30°C at water flow rate of 0.5-2.0 l/min. The maximum achievable comprehensive COP was 5.13 when the water flow rate was set at 2.0 l/min. The COP of the designed air conditioning-heat pump unit is improved approximately 38% when compares to the typically air cooled counterpart. Moreover, according to the economic analysis, the unit is also economically attractive with the air conditioning-heat pump unit that has payback period of 4 months.