| With the continuous deepening of my country’s energy saving and emission reduction and "coal to electricity" policies,air source heat pumps have been more and more widely used due to their energy saving,environmental protection,safety,reliability,and ease of control.However,frost formation in winter conditions is an unavoidable problem for air source heat pumps.Frost will cause the heat transfer resistance of the outdoor evaporator to increase,and the heat transfer performance will deteriorate,and the operating efficiency of the entire system will be significantly reduced.Sex.At present,many scholars have conducted in-depth research on the frost suppression method of the air source heat pump.Among them,some scholars use electric heating to preheat the air at the entrance of the outdoor evaporator,so as to achieve the purpose of frost suppression.However,electrical energy is a high-quality energy source,and it is not energy-saving to preheat the air with electric heating.Aiming at the deficiencies of the above methods,a preheated air source heat pump system is proposed,which has a good frost suppression effect in a high humidity environment.This article first explains the design idea of the preheated air source heat pump system: by using the lower grade heat generated by the air source heat pump to preheat the air at the inlet of the evaporator to achieve the purpose of frost suppression,this approach is more direct than electricity Heating is more energy efficient.Then the form of the air-to-air heat exchanger was screened,and the sensible heat exchanger was selected for use.Finally,the sensible heat exchanger,air duct and preheating mixing box are combined to design a preheatded air source heat pump system.Aiming at the proposed new system,the Energy Plus energy consumption simulation software was first used for simulation research,and then an experimental platform was built for experimental research.Through simulation calculations and experimental tests,the following conclusions were finally drawn:(1)In a high humidity environment with a relative humidity of 85%,the preheated air source heat pump system has a good frost suppression effect.(2)In different temperature regions,using different preheating air volume in different regions can obtain the "double benefit" of frost suppression and energy saving.The outdoor air temperature is below-13 ℃,and the maximum preheating air volume ratio of 31% can be used to make the system achieve frost-free operation,the unit has no defrost power consumption.At the same time,because the preheating greatly improves the COP of the unit,the electric power can be reduced by12.4% to achieve frost suppression and optimal state of energy saving.When the outdoor air temperature is-13 ～-3 ℃,if you want the best frost suppression effect,adjust the proportion of the preheating air volume to the maximum,you can achieve a71.3% reduction in frost rate,and the electrical power of the unit is reduced by 4.9%;Frost is suppressed while energy saving is optimal.A 23% preheat air volume ratio can be used to reduce the frost rate by 54.6% and the unit’s electrical power by 12.1%.When the outdoor air temperature is above-3 ℃,the frost suppression effect of the system is inversely proportional to the energy saving effect.Therefore,in order to obtain the best frost suppression effect,the maximum preheating air volume ratio is required.At this time,the electric power is increased by about 40%,and the energy saving of the system is relatively poor. |
