Performance Optimization And Experimental Investigation For Transcriticai CO₂Heat Pump Water Heater

Ozone layer depletion and the greenhouse effect is present serious environmental problems facing humanity. Use of natural refrigerant CO2, not only helps to reduce mitigate the greenhouse effect and ozone depletion, while CO2trans-critical cycle in the presence of the exothermic temperature slip, especially for heat pump water heaters. For higher operating pressure and lower COP of transcritical CO2heat pump hot water, is theoretical system optimization and experimental studied is made.For heat pump water heater, the design should be based on GB/T23137-2008.The establishment of the compressor, evaporator, gas cooler and the throttle steady-state model. Analysis showed that:supercooling cycle performance parameters are favorable, the undercooling is increased by1℃, COP increased by7.8%. Superheat increased1℃, COP increased by0.4%. Thermal efficiency of the regenerator for each additional0.1, COP increased by1.3%. Condensing temperature and evaporating temperature is still the most important factors affecting cycling performance.Evaporating temperature and condensing temperature is increased by1℃, COP increased by13.4%and decreased by12%.External heat source directly affect the condensing temperature and evaporating temperature. Relying on the existing bench, cooling water and frozen water circulation system of parameters on the performance of experiments. The results showed that:the cooling water flow increases resulting in lower cooling water outlet temperature, so that the water temperature may fail to meet requirements. Frozen water flow have a small influence on heating coefficient of system cycle. Cooling water inlet temperature of rising, making a heating coefficient reducing. Frozen water inlet temperature rise, to transcritical CO2heat pump water heater influence is not big.Improve the efficiency of the transcritical CO2cycle heat pump water heating cycle to the promotion and application of key. Select the appropriate gas cooler and evaporator heat exchanger type, model and the use of solar assisted water supply and two-stage compression system to improve overall system efficiency is an effective way.