Air Source Heat Pump Assisted Solar Water Heating System Optimization Study In Xichang Area

Under the pressures of energy crisis and environmental pollution,the exploitation and utilization of renewable energy,such as solar energy has been highly valued and strongly supported.However,due to the instability of solar energy resources,solar hot water system should be provided with auxiliary heat source to ensure the actual energy supply,the organic integration of solar energy and air source heat pump is being taken more and more attention by scholars at home and abroad in which they can give full play to their respective advantages.So far,there is some disfigurements or deficiencies in the related research of the key parameters optimization and operation control of the air source heat pump assisted solar water heating system.The research was in process combined with the engineering case of Xichang area.The key parameters of the air source heat pump assisted solar water heating system was optimized and the operation mode is systematically analyzed under the selected typical day.The findings can provide a theoretical reference for the reasonable design of the air source heat pump assisted solar water heating system.First,the air source heat pump assisted solar water heating system adynamic simulation model is established on the platform of TRNSYS.The interactive orthogonal design method is proposed to investigate the key parameters and their interactions affecting the performance of air source heat pump assisted solar water heating system,solar fraction was selected as the target parameter and tilt angle,collector area,water tank volume and the rated power of heat pump were selected as influencing factors.Range analysis and variance analysis were applied to study the incidence of these factors and their interactions for solar fraction.The research results indicate that these four key parameters should be synchronized to optimize in the actual air source heat pump assisted solar hot water system optimization.In addition,based on the analysis sensitivity of the system about key parameters,the model of system design parameters optimization is established using Hooke-Jeeves algorithm.The life cycle cost of the system is selected as the optimization objective and the tilt angle,collector area,tank volume and the rated power of heat pump are selected as optimization variables,to optimize key parameters synchronously by means of Hooke-Jeeves algorithm.The research results indicate that the COPasys is increased and the operating cost of the system is reduced compared with the initial design.The decreasing rate of electricity consumption of the whole year is increased by 9.11%.On this basis,the recommended matching principles of key parameters are proposed that the tank volume per collector area is 70 L/m2,the heat pump power per collector area is 60 W/m2 and the tilt angle equals to the local latitude ?-60.During the same type design of the air source heat pump assisted solar water heating system,the rated power of heat pump,collector area,tank volume and tilt angle can be optimized in sequence according to the above matching principles.Finally,based on the system design parameters optimization,the method of classification in meteorological parameters is firstly proposed to optimize the operation mode of air source heat pump assisted solar water heating system under different meteorological parameters,and two first class indicators(solar radiation,air temperature)and five second class indicators are selected as the criteria.By using clustering method,the 365 days' weather of the four time periods of the year in Xichang is in clustering analysis and the results are confirmed by Bayesian discriminant analysis.Furthermore,under the selected typical day of each group,the optimal heat pump operating time of each group is determined by the minimum energy consumption which is treated as the optimization objective.The results show that the recorded 90 meteorological days of the first time periods(including December,January,February)in Xichang can be clustered into 11 groups,the 123 days'weather of the second time periods(including March,June,July,August)can be clustered into 9 groups,the 61 days' weather of the third time periods(including April,May)can be clustered into 4 groups,and the 91 days' weather of the third time periods(including September,October,November)can be clustered into 8 groups.The Bayesian discriminant analysis method is used to verify the classification results of each period that the result is good.The method of classification in meteorological parameters for the whole year in Xichang more reasonable.Besides,according to the classification results of Xichang area,the best opening time of heat pump unit have been simulated and research in the typical days of each groups,and the accuracy of the research on the best opening time of heat pump is verified,and get the system running strategy for the whole year.The research method can provide a new way for the research of the air source heat pump assisted solar water heating system.