| To solve the problem of frost formation on the evaporator surface when the air source heat pump is used in wet and cold environments,this paper proposes a new solar-assisted frost-free air source heat pump that combines dry air with a solar house shell to achieve frost-free operation of the evaporator and efficient heating of the heat pump system.This paper analyzes the evaporator frost formation process and frost growth law,takes the relative humidity of air as the focus of the system to achieve frost suppression,uses water vapor-free air for heat transfer,and investigates the heat transfer characteristics of this new system by numerical simulation.Firstly,the models of frost-free system and traditional air source heat pump system with frost conditions proposed in this paper are established,and the differences of evaporator heat absorption between them are analyzed,and the results show that the performance of traditional air source heat pump starts to be weaker than that of frost-free air source heat pump after 2 hours of frost phenomenon.The effects of different solar room shell sizes on the heat absorption performance of the heat pump system and the heat transfer performance of the shell were investigated.Secondly,the changes of evaporator heat absorption and total heat transfer from the solar house shell under the conditions of fan wind speed of 5m/s,10m/s,15m/s,20m/s and 25m/s are analyzed,and the phenomenon that the fan energy consumption of this system can be recovered by the evaporator in the form of heat energy is found.The effects of three fan-evaporator spacings on the heat transfer from each side of the solar house shell and the optimal evaporator location of the system are discussed.Then,the performance of the system at 8:00,10:00,12:00,14:00 and 16:00 hours of daytime operation is discussed,and it is found that the heat pump evaporator heat absorption shows an "M" shaped trend during the daytime.In addition,the temperature of the outer surface of the solar house enclosure was analyzed throughout the day,and it was found that the surface of the solar house enclosure does not frost within the operating conditions set in this paper.Finally,in order to understand the energy saving of the system,a comparison with the frost condition of the traditional air source heat pump was made,and it was found that the energy saving of the system was 58.2kWh per day in continuous operation during the heating season and 28.9kWh per day in daily operation(8:00～18:00).The results of this paper can provide new solutions for air source heat pumps in the field of decentralized heating and district heating in cold regions. |
