Technologies to Improve the Performance of A/C Systems in Hot Climate Regions

Air conditioning contributes significantly to building energy consumption in hot climate regions. In addition to greater cooling requirements in hot climates, cooling equipment efficiency decreases with increasing outdoor temperature. Therefore, it is advantageous to develop improved technologies that can achieve higher efficiency at high ambient conditions. In this paper, two novel compression technologies are investigated for application in high ambient temperature air conditioning via numerical simulation. These technologies are liquid flooded compression with regeneration and vapor injected compression with economizing. The systems are modeled using the EES software (Klein, 2012) and compared with a baseline conventional vapor-compression cycle that utilizes R410A as the refrigerant. The cycle enhancements are considered for a number of refrigerant alternatives, including R410A, propane (R290), R32, and R1234yf. Parametric studies are conducted for air conditioning design conditions to predict the improvements in coefficient of performance (COP) for both system configurations with the various refrigerants. The simulation results show that the two novel technologies provide improvements in air conditioner performance and lower compressor discharge temperatures at high ambient temperatures. With respect to compressor discharge temperature, the vapor injection technology is superior to the oil flooding concept for the investigated working fluids. The COP comparisons indicate that oil flooding only improves the system performance when using the refrigerant R1234yf with a 14% increase in COP, whereas the vapor injection leads to significant improvements for all refrigerants with a maximum improvement of 21.5% for the refrigerant R410A.