Performance Optimization Of The LPG Vaporization System Utilizing Solar Assisted Heat Pump

With the rapid development around the world,the total amount of global energy consumption is increasing year by year,and the demand for clean energy and renewable energy is constantly increasing.In order to efficiently use various energy sources,this paper conducts a performance optimization study on the LPG vaporization system utilizing direct-expansion solar assisted heat pump(named as DX-SAHPV system).Direct-expansion solar assisted heat pump(DX-SAHP)is a thermal device with good heat collection performance and low economic cost,and it is also an important component of the DX-SAHPV system.This paper uses the finite-time thermodynamic theory to establish the DX-SAHP general thermodynamic model,and establishes the heat transfer model of the collector/evaporator under dry and wet conditions.It takes the heating performance and economic performance of DX-SAHP as the optimization goal,calculates the thermal economic parameters of the system under different working conditions,and analyzes the impact of meteorological conditions,structural parameters and economic parameters on the performance of DX-SAHP.The research results show that when the design parameters are the same,the heating performance of DX-SAHP under wet conditions can be effectively improved by 20% ～50%;meteorological parameters and structural parameters have an important influence on the optimization characteristics of DX-SAHP.This paper establishes the DX-SAHPV system full-condition dynamic simulation mathematical model.According to the characte ristics of the system’s annual gas consumption and the natural gasification characteristics of LPG,eight operating modes of the DX-SAHPV system are proposed,so that the operation of the system efficiently fits the weather changes throughout the year and the user gas load fluctuation.This paper uses Matlab software to simulate the DX-SAHPV system throughout the year,and the annual operating distribution of each mode of the system is obtained,and the annual operating performance of the system is in-depth studied.The annual gas supply load of the DX-SAHPV system is 30497.89 k Wh.The annual heat supply of DX-SAHP is 13443.8k Wh,and the annual average COP is 3.51.The lowest monthly average COP of the year is 2.66 in January,and the highest monthly average COP of the year is 4.42 in June.The annual operation performance is good.On the basis of the DX-SAHPV dynamic simulation simulation throughout the year,this paper takes a 1000 residential community in Beijing area as the gas supply object.By changing the design parameters of the hot water storage tank volume,the system start/stop temperature and the start/stop temperature difference,the DX-SAHPV system under different design conditions has been dynamically simulated throughout the year,and the annual operating characteristics of the system under various design conditions have been optimized and analyzed.The results show that when the volume of the hot water storage tank is increased from 1000 L to 2000 L,the total annual energy consumption of the DX-SAHPV system is reduced by544.6k Wh,and the thermal economy of DX-SAHP is reduced by 8.9%.When the start temperature of DX-SAHP rises from 313 K to 323 K,the total annual energy consumption of the system increases by 1049.2k Wh,and the thermal economy of DX-SAHP is reduced by 13.9%.When the start/stop temperature difference of DX-SAHP is reduced from 10 K to 5K,the total annual energy consumption of the system increases by 797.6k Wh,the thermal economy of DX-SAHP increases by2.9%.In order to ensure the efficient operation of the DX-SAHPV system throughout the year,the volume of the hot water storage tank is designed to be 1000 L,and the start/stop temperature of the DX-SAHP should be set at 313K～318K.