| The solar-assisted heat pump system adopts the solar hot water energy storage method to assist the heat pump heating method,which can solve the technical defects of the traditional solar-assisted heat pump system in extreme weather such as reduced efficiency.At present,few studies have been performed on the temperature of the water entering the heat pump system from the solar energy storage(the auxiliary water temperature).The research also found,the ambient temperature,auxiliary hot water temperature,and opening degree of the EEV have a significant impact on the heating capacity and COP of heat pump systems with auxiliary hot water.However,there are few studies on the effect of these three factors on the performance of solar-assisted heat pump systems.In this paper,a hot water-assisted heat pump heating system and a solar hot water-assisted heat pump drying system are set up indoors and outdoors.We carried out an experimental study of the performance of a heat pump system with auxiliary hot water under different ambient temperatures,auxiliary hot water temperatures,and opening degrees of the EEV.In the solar hot water auxiliary heat pump drying system,potato chips are used as the drying material,and solar hot water auxiliary heat pump drying experiments with different hot water temperatures and single heat pump drying experiments are carried out in winter.It is concluded that the solar hot water auxiliary heat pump system can effectively improve the system efficiency under low-temperature conditions.The main research contents are as follows:(1)In the indoor hot water-assisted heat pump heating system experiment,36 sets of experiments were designed by the orthogonal combination method,and the system heating and COP were calculated.The calculation results show that when the opening degree of the electronic expansion valve is the same,the higher the simulated ambient temperature and the auxiliary hot water temperature,the higher the heating capacity and COP of the system.However,the higher the ambient temperature,the more limited the increase in the heating capacity of the auxiliary hot water,and as the temperature of the auxiliary hot water increases,the increase in the heating capacity is gradually slowing down.When the simulated ambient temperature and auxiliary hot water temperature remain unchanged,as the opening of the electronic expansion valve decreases,the greater the system heating capacity,the higher the COP.(2)By comparing the system heating capacity and COP under different working conditions,it is found that: At a lower ambient temperature,increasing the appropriate auxiliary hot water temperature can make the COP higher than the COP under higher ambient temperature conditions.It shows that auxiliary hot water has a significant effect on the improvement of COP.Under natural conditions,this experimental method can be used to achieve the purpose of improving the efficiency of the heat pump system in a low-temperature environment.(3)The Box Behnken design of Design Expert software is used to analyze the influence of system heating and COP under three different factors designed in the experiment of the hot water auxiliary heat pump heating system.The analysis shows that the quadratic equation model can accurately describe the change law of system heating capacity and COP.At the same time,it is found through the response surface diagram that among the factors that affect the system performance,the auxiliary hot water temperature was the most important factor,followed by the ambient temperature and opening degree of the EEV,which fully shows that the addition of auxiliary hot water can greatly improve the system performance.(4)Combined with the theoretical results of the indoor experiment,the outdoor solar hot water auxiliary heat pump drying system experiment is carried out,and the system performance is analyzed and the following is obtained: The average system heating capacity of the auxiliary hot water temperature of 30 ℃ group increased by3.82% and 16.12% respectively compared with the average system heating capacity of the basic group and the auxiliary hot water temperature group of 10 ℃;the average system heating capacity of the basic group increased by 11.84% compared with the average system heating capacity of the auxiliary hot water temperature of 10 ℃ group.The average COP of the auxiliary hot water temperature of 30 ℃ group was 8.24%and 34.16% higher than that of the basic group and the auxiliary hot water temperature of 10 ℃ group,respectively;the average COP of the basic group was 23.95% higher than that of the auxiliary hot water temperature of 10 ℃.It is found that in the outdoor experiment,the solar hot water auxiliary system with the auxiliary hot water temperature of 10 ℃ does not provide effective heat assistance to the heat pump system as in the indoor experiment.(5)Analyze the drying performance of the solar hot water auxiliary heat pump drying system,the calculation result shows that the SMER of the auxiliary hot water temperature of 30 ℃ group increased by 29.84% compared with the basic group;compared with the basic group,the MER of the auxiliary hot water temperature of30 ℃ group increased by 23.94%;compared with the basic group,the energy saving efficiency of the auxiliary hot water temperature of 30 ℃ group increased by 5.27%.The drying time is opposite to the moisture content of the dry base.The drying time of the auxiliary hot water temperature group is 10 ℃ is 12 hours,and the drying time of the basic group is 10 hours,the drying time of the auxiliary hot water temperature is30 ℃ is 9 hours.The moisture content of the dry basis is respectively: 9.588%,8.039%,5.801%.(6)Observing the appearance of the dried sample,it can be seen that the finished product dried by the solar hot water-assisted heat pump drying system has a uniform color and bright yellow.The traditional natural-air-dried finished product is dark gray in color,and a small part of it is jet black.Therefore,the use of solar hot water auxiliary heat pump drying system not only saves time but also the appearance of the dried product is better. |
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