| China’s building energy consumption and total carbon emissions are increasing year by year,and the central heating system has problems of single product,poor safety and environmental pollution.The distributed heating system of solar-assisted air source heat pump has become one of the effective ways to reduce building energy consumption and carbon emissions.First of all,this paper proposes air-cooling concentrating photovoltaic/thermal coupled air source heat pump heating system(ACPVT-ASHP)and water-cooling concentrating photovoltaic/thermal coupled air source heat pump heating system(WCPVT-ASHP).ACPVT-ASHP system uses concentrating PVT to preheat the air and improve the heat source temperature of the heat pump.WCPVT-ASHP system uses the concentrating PVT to preheat the heating water,which can realize the direct heating of the concentrating PVT and improve the inlet water temperature of the heat pump.Taking the office building in Beijing as the heating object,the above system simulation model is built in TRNSYS,and the performance of the system in the heating season is obtained by simulating it in hours.Secondly,the energy efficiency,exergy efficiency,annual total cost(ATC),primary energy consumption(PEC),primary energy saving rate(PESR)and other indicators are selected to comprehensively evaluate the systems.Take the air source heat pump heating system(ASHP)as a comparison system,and compare the performance and cause of variation for systems from the typical day and heating season.The results show that compared with ASHP system,the average annual COP of ACPVT-ASHP system increases by 22.8%,PEC decreased by 1191.8kgce,PESR increases by 567%,operating cost decreases by 1713.5CNY and ATC increases by 33.7%;the average annual COP of WCPVT-ASHP system decreased by 6.0%.PEC decreased by 1075.37kgce,PESR increased by 528%,operation cost decreased by 1467.2CNY and ATC increased by 43%.Due to the input of solar energy,according to the first and second laws of thermodynamics,compared with ASHP system,the energy efficiency of ACPVT-ASHP system is reduced by 49.2%,and the exergy efficiency decreases by 23.5%;the energy efficiency of WCPVT-ASHP system is reduced by 59.7%,and the exergy efficiency decreased by 42.2%.Compared with the other two systems.ACPVT-ASHP system has significant advantages in energy saving,improving COP and reducing carbon emissions.Finally,the ACPVT-ASHP system is optimized with multiple objectives.The decision variables are the length of PV,the number of heat collecting tubes and the heat pump rating.The objective functions are ATC,PEC and the average annual COP.A method of using Grasshopper to call TRNSYS model and using Octopus operator to perform multi-objective optimization is proposed.Linear Program-ming Technique for Multidimensional Analysis of Preference(LINMAP),Technique for Order of Preference by Similarity to Ideal Solution(TOPSIS)and Shannon Entropy method are used to select the optimal solution.The results show that the deviation index of the optimal solution selected by LINMAP method is the smallest.The decision variables of the optimal solution of the ACPVT-ASHP system after optimization are that the length of the CPVT panel is 1.90m,the number of heat collecting tubes is 71,and the rated heat of the heat pump is 10.1kW.This decision-making scheme is a scheme that improves energy saving and heat pump performance at the expense of certain economy.The results of this paper provide theoretical support for the promotion and application of CPVT technology,provide new ideas for building clean heating,and lay a theoretical foundation for the promotion and implementation of CPVT coupled air source heat pump heating system. |
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