| With the improvement of people’s requirements for building thermal comfort,the rise in building energy consumption has aggravated power loads and greenhouse gas emissions.The problems of high energy consumption from electric heating and the lack of rational utilization of solar energy resources in traditional non-central heating areas have not been effectively solved.Therefore,this paper proposed a photovoltaic(PV)driven air source heat pump(ASHP)heating system(PV-ASHP)with thermal energy storage to meet the needs of building heating and domestic hot water(DHW)at the same time.The hot water storage tank was added to improve the real-time power consumption of PV generation and reduce the grid consumption of the system at night.Experimental and simulation studies were carried out on the operating characteristics and energy transfer law of the system under different heat load modes,and the system was optimized and evaluated for energy savings,economy and environmental protection.The main work was as follows:1.Based on the meteorological data and building thermal parameters in Kunming,Yunnan,the thermal load of a 43.89 m~2 heating room was simulated and analyzed.Taking the maximum room heat load in the simulation results as the design boundary value,the component selection calculation of the PV-ASHP with thermal energy storage was carried out,and the experimental platform was built.In order to study the laws of photoelectric conversion,electrothermal conversion and storage and utilization of electrothermal energy in the system,a simulation model of PV-ASHP was built by TRNSYS software based on the established mathematical model of important components of the system.Three operating modes and six types of system operation evaluation indexes were proposed to study the influence of step-by-step increasing room heat loads on the heating performance of the system.2.The PV generation subsystem,ASHP heating subsystem and room heating subsystem in the simulation model were verified by experiments.The results showed that the deviation between simulation and experimental results was less than 10%.Based on the transient results and annual statistical results of the verified simulation model,the energy transfer characteristics of the hot water storage tank during the heating process of the system were analyzed,and the operation performance of the system under three different thermal load conditions of the room was further explored.The results showed that the strategy of supplying energy and storing energy at the same time during the day and releasing heat energy at night made the heat energy obtained by room heating and DHW in the evening account for 17.4%and 31.5%of the average heating capacity of ASHP during the day.Compared with meeting the single heating needs of the room,meeting both room heating and DHW could improve the energy efficiency of the system.This synergistic effect between room heating and DHW made the COP of ASHP,the self-consumption rate and the self-sufficiency rate of PV increase by 131.25%,10.53%and 9.56%,respectively.When 82 W photovoltaic modules were installed per square meter of building area,the electricity that PV could directly provide to ASHP accounted for 55.54%of the power consumption of the whole system every year.3.Based on the Hook-Jeeves algorithm,the optimization software Genopt was used to optimize the installation position of photovoltaic modules,and the installed capacity of photovoltaic modules with PV generation equal to the total power consumption of the system was optimized.The results showed that after optimization,the annual PV generation increased by 0.18%due to receiving more solar irradiation.After the optimization of the installed capacity of PV,the proportion of PV generation to the total electricity consumption of the system was increased from 80.79%to 99.65%,and the corresponding optimal capacity was 4500 W.4.The system proposed in this paper was compared with the electric heating system and the single ASHP system in terms of energy savings,economy and environmental protection.The results showed that the PV-ASHP system had greater advantages in energy savings and emission reduction than the control system.Compared with the electric heating system,the annual standard coal savings of the single ASHP system and the PV-ASHP system were 0.669 t and 2.488 t.The annual carbon dioxide emission reductions were 1.855 t and 6.899 t.The PV-ASHP system had the highest initial investment and the lowest annual operating cost among all systems,and its static investment recovery period was between 3.61 and 6.04 years.The advantages of PV-ASHP system in energy savings,environmental protection and economy will provide a reference value for the application of PV driven ASHP combined with building efficient heating technology in China. |
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