Research On Performance And Benefit Of Solar Integrative Air Source Heat Pump With Direct Heating By Refrigerant

Air source heat pump for radiant floor heating with direct heating by refrigerant(ASHP)is a kind of self-regulating space heating technology with flexible layout and convenient operation,which is more energy-efficient and environmentally friendly than air source heat pump for radiant floor heating with low-temperature warm water.Furthermore,ASHP can also utilize the solar energy for free with an energy grade very close to space heating to improve the heating performance.The development of ASHP combining with solar energy can effectively overcome the disadvantage of heating performance instability in the solar space heating device with the change of time and space.It is closely in line with the national strategy orientation and international development frontier for science and technology and the social livelihood of the people,which has a clear research meaning.Solar integrative air source heat pump for radiant floor heating with direct heating by R407c refrigerant(SIASHP)is put forward.SIASHP carries the existing capillary copper pipe network radiant floor heating condenser and the novel aluminum anodized solar selective absorption coating electrolytically colored on the surface of finned tube evaporator which integrates the solar thermal collector with the ASHP evaporator to be the solar finned tube evaporator as a whole.The novel modified polymethyl methacrylate shell and refrigerant bypass are also set up.SIASHP is a balanced decision between the maximum utilization of both solar radiation and air source for space heating and the minimum occupation of architectural space.The performances of part load rate conditions of SIASHP are studied by means of a DC inverter controller.By means of the TRNSYS energy consumption simulation software,set the device boot time as 08:00~18:00 and the indoor space heating target temperature as 20±2℃.On the basis of typical meteorological year data of Jinzhong in Shanxi Province,the results conclude that the average COP_h of SIASHP is 3.3%higher than the ASHP in January as the coldest month in the heating season on one side,while on the other side,the average COP_h of SIASHP is 7.2%higher than the ASHP in March as the warmest month in the heating season,reflecting the coupling influence of solar finned tube evaporator on the heating performance of SIASHP.The evaluation parameters PMV-PPD for indoor thermal environment state that both heating devices can build levelⅠindoor thermal environment with better thermal comfort.The heat transfer characteristics of solar finned tube evaporator are further analyzed and the conclusions are that the effective utilization rate of solar irradiance is 82.9%on average which is 4.7%lower than the theoretical value,and the normal emissivity of thermal energy is 9.2%on average which is 16.4%lower than the theoretical value,and the average heating capacity rate between solar radiation and air source is 0.132 in the typical heating season.In general,the comprehensive utilization characteristics of solar radiation and air source for SIASHP are excellent.Aiming at the inconsistent definitions of COP among the national standard specifications,put forward the classification of application conditions of COP and EER in order to eliminate the ambiguity based on investigating their history and definitions in ASHRAE.A kind of energy-saving potential evaluation method for heat pump is also suggested and the conclusion is when the practical COP_h is higher than 2.7,the primary energy ratio of heat pump can be higher than one.On the basis of construction method of transient integrated part load value(IPLV),propose the seasonal part load value(SPLV)containing the physical meaning of running time.The frost resistance coefficient(FRC)describing the energy-saving performance level of ASHP during defrosting is proposed as well.Experimental comparative investigation for SIASHP has been conducted including the COP_h characteristic fitting formulas under the conditions of-15~7℃outdoor dry-bulb temperature,0.71~3.71g/kg(a)moisture content and 120~180W/m~2 solar irradiance.The properties of frost resistance and IPLV and SPLV are also comparatively researched under the conditions of-11~-9℃outdoor dry-bulb temperature and 115~135W/m~2 solar irradiance.The average IPLV of SIASHP is 2.54 which is 14.9%higher than the 2.21 of ASHP,while the average SPLV of SIASHP is 2.53 which is 15.5%higher than the 2.19of ASHP.Under the conditions of reverse cycle defrosting with 100%load rate,the FRC of SIASHP is 8.7%which is 14.5%higher than the 7.6%of ASHP.Improve a set of exergy analysis method with the experimental feasibility researching on the coupling characteristics of various components in the SIASHP.Compared with the ASHP,experimental investigation for SIASHP has been conducted including the exergy efficiency,exergy improvement potential and the thermodynamics process quality number under the conditions of-15~7℃outdoor dry-bulb temperature and 120~180W/m~2 solar irradiance.The average exergy efficiency of SIASHP is 77.67%which is 8%higher than the71.95%of ASHP.The average exergy improvement potential of SIASHP is104.7W which is 1.5%lower than the 106.3W of ASHP.The average thermodynamics process quality number of SIASHP is 59.36%which is 5.4%higher than the 56.34%of ASHP.The structure and arrangement of capillary copper pipe network condenser suitable for SIASHP still need further optimized design and there is still more optimized design space for the solar finned tube evaporator.A system for evaluating the benefit of SIASHP from the power side to the service side is formed.Come up with a kind of macroscopic economic benefit evaluation method estimating the influence of energy price comparison on the energy-saving benefit of heat pump.Under the conditions of average technical and economic parameters in North China and the civil electricity,natural gas and power coal price calculated by RMB/kWh,RMB/Nm~3 and RMB/kg respectively,the 1:4 civil electricity and natural gas price comparison and the 2:3 civil electricity and power coal price comparison are the economic benefit tipping points of SIASHP compared to natural gas boiler heating and regional coal-fired boiler heating technology,respectively.Based on the economic benefit tipping points,the lower the energy price comparison is,the more the economic benefit of heat pump is.The annual cost of SIASHP is 27.24RMB/m~2 which is lower than the 27.65RMB/m~2 of ASHP,indicating that the SIASHP has a better microscopic economic performance.Come up with a kind of environmental benefit evaluation method estimating the influence of PM2.5 concentration in the atmosphere on the COP_h of SIASHP.When the PM2.5 concentration in the atmosphere is less than 90μg/m~3,SIASHP can obtain the environmental benefit.