Experimental Research on Micro Channel Heat Exchanger Application for Wall-mounted Heat Pump Water Heater [11]

Heat pumps provide comfort in room and water heating with superior efficiency. Due to that, the heat pumps produce renewable energy, save energy consumption and avoid greenhouse gas emissions. Micro channel heat exchanger (MCHE), gets the attention from air-conditioning refrigeration industry because it has many advantages such as high heat transfer efficiency, less refrigerant charge, compact size and light weight. In home appliance water heater market, electric heater type is leading product, the quantity amount over 10 million per year, but the conversion efficiency of electricity to thermal always below 95%. For energy saving and renewable, more and more heat pump water heater are replacing the electric water heater. In this paper, we focus on the heat pump water heater performance and efficiency by MCHE replacing fin-tube evaporator and optimizing baseline MCHE condenser. Sanhua MCHE company developed MCHE for heat pump outdoor unit heat exchanger and study the application process. The performance, weight and refrigerant charge of the heat pump system using MCHEs are compared with copper tube & fin heat exchangers.
According to the experiments of 4 type heat exchanger combination dynamic running process, we can get below conclusion:
(1） For evaporator of heat pump water heater, MCHE can replace the baseline fin-tube one, and reach the same level of performance, but more lighter and lower cost;
(2） For condenser of heat pump water heater, 16mm MC tube can replace the baseline 25mm one, and tube pitch will be smaller, the tank contact area more bigger, so the unit COP could be increased about 0.3, efficiency grade could be increased 1~2 level, heating velocity also higher a little.
(3） As this kind of heat pump water heat unit is always installed in bathroom, the additional benefit is, it could be used as a dehumidifier for keeping room dry and comfortable when water heated.