Simulation Of Small-scale Air Source Heat Pump Water Heater

This thesis is based on the working principle of small-scale air source heat pump waterheater. It establishes the steady-state model of the four components of the unit respectively,including scroll compressor, tube condenser, thermal expansion valve and finned tubeevaporator. And based on certain parameters coupling relationship, it establishes the modelof the entire system. Through the simulation study of its operating characteristics, it hasanalyses the influence of the ambient temperature, cooling water inlet temperature andcooling water flow on the system performance and provides the basis for the practicalapplication of control and regulation.The results indicate that the ambient temperature has a large influence on air sourceheat pump water heater performance. The heating capacity and power consumption areincreasing and the COP is increasing significantly with the ambient temperature rising.When the wet and dry bulb temperature is7/6℃、20/15℃、35/24℃, the system COP is2.76、3.76、5.5respectively. Meanwhile, when the cooling water inlet and outlet temperature is15/55℃, the cooling water flow is increasing as the ambient temperature rises. When thewet and dry bulb temperature is7/6℃、20/15℃、35/24℃, the system cooling water flow is0.018kg/s、0.028kg/s、0.044kg/s respectively. When the cooling water flow rate is0.025kg/s,the cooling water inlet temperature range is5-20℃, the unit’s water outlet temperature willrise, but its power consumption and exhaust temperature increases, and its heat capacity andsystem COP decreases. So, if a higher water temperature is not required, the cooling waterinlet temperature does not need rise.When the cooling water inlet temperature is15℃, thecooling water flow rate range is0.025-0.035kg/s, the system heating capacity increases andthe power consumption reduces, so the system COP increases, and its exhaust gastemperature, exhaust pressure and pressure ratio are decreases, it can improve the operatingconditions of the unit, but with the increase in traffic, the water temperature decreases,Therefore need to consider whether the water supply temperature can meet the requirements.