Experimental Study On A Novel Air Source Gas Engine Heat Pump Supplying Cold And Hot Water

The air source gas engine heat pump adopts natural gas as the energy source and operates the heat pump system by a gas engine.However,the existing heat pump system usually uses an expansion valve to achieve the operation of cooling and heating conditions.The disadvantage is that when the cooling and heating modes of the heat pump system are switched,a single expansion valve cannot always be installed on the pipeline that is very close to the inlet of the evaporator,which makes the heat exchange effect of the evaporator in one of the operating modes worse.It is difficult to ensure that the system runs efficiently throughout the year.In addition,the waste heat of the gas engine is completely wasted to the environment in summer,and if it is directly used to assist evaporation in winter,its performance is worse than directly used to heat hot water.It can be seen that the waste heat utilization mode and operation mode of the gas engine need to be improved.In response to the above problems,this article improved the operating system,performed thermal calculations and component selection,used three thermal expansion valves and a non-standard design finned tube heat exchanger,designed an electrical control system,and developed a Experimental research on the influence of air source gas engine heat pump chiller and hot water units on the performance of the system under the year-round operating conditions.The main results are as following:When operating in summer conditions,the impact of ambient temperature on system performance is small,while in winter operating conditions,the impact of ambient temperature on system performance is greater.Moreover,the waste heat recovery effect of engine is important.Under all summer conditions,the system PER₁?primary energy ratio with heat recovery?is higher than PER₂??primary energy ratio without heat recovery??,and the average difference between the two is 0.59.It can be seen that air source gas engine heat pump cold and hot water units do not consider waste heat recovery in summer conditions and it is not economical to separately cool.For winter,the engine's waste heat can effectively overcome the problem of winter heating capacity attenuation.Therefore,it can be concluded that only by making full use of the engine's waste heat can the superiority of the air source gas engine heat pump cold and hot water units be reflected.In the transition season,the impact of external conditions on system performance is basically the same as that in winter heating conditions.However,compared with the winter conditions,the system performance of the unit is higher than the winter conditions,but the suction and exhaust of the units are also higher than the winter conditions.It is easy to blindly pursue excessive hot water temperature causes a series of high-voltage faults in the system.Therefore,when supplying domestic hot water in the transition season,the hot water temperature can meet the sanitary requirements of domestic hot water,and the set temperature should not be too high.Through experimental research on the annual operating performance of air source gas engine heat pump cold and hot water units,it can be seen that after using three thermal expansion valves and a non-standard design finned tube heat exchanger,the unit can run stably and has high energy efficiency.The average value is as high as1.45 which means that the system is able to achieve efficient operation throughout the year.