72 Application of Residential R744 Heat Pump Water Heater in Zhongyuan Area of China

Due to the harmful effects upon the environment, the CFCs(chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons) and HFCs (hydrofluorocarbons) with a high Global Warming Potential (GWP) were banned by the international protocols. Natural alternatives are the sustainable solution for the environment and energy consumption, among which R744 is an excellent substitute for the synthetic fluids, especially in heat pump water heater applications. The distributed parameter model was proposed to investigate the system performance of a residential R744 heat pump water heater. The model was developed using Engineering Equation Solver (EES) software. The outdoor air temperature and tap water temperature in Zhengzhou, the typical city in Zhongyuan area, were utilized to practically research the performance of the system. Based on these calculated data, Total Equivalent Warming Impacts (TEWIs) was computed. Results show that the transcritical R744 heat pump water heater under design conditions has a higher COP of 4.663. When the unit is driven in Zhongyuan area of China an annual average COP of about 4.88 is achieved, which means R744 heat pump water heater is an excellent way for producing water in Zhongyuan. Compared with the hot water heater using other energy sources, the R744 heat pump water heater averagely decreases about 48% in the CO₂ amount produced. Therefore, the R744 based system is characterized in a higher energy efficiency and a very effective way for markedly reducing CO₂ emissions.