Capacity Matching And Operation Simultaneous Optimization Of Solar Energy And Air Source Heat Pump Combined Heating System

Solar energy is a renewable energy source with the advantages of cleanliness,low price and wide distribution.The air source heat pump uses air as a source of cold and heat,and requires only a small amount of electric energy input to achieve the purpose of building cooling or heating,which is beneficial to the efficient utilization of resources and sustainable development.For Tibetan areas and western Sichuan,where conventional energy is scarce,the utilization of solar energy and air resources heat pumps plays a vital role in mitigating conventional energy consumption,promoting building energy efficiency and relieving the tense energy situation.The solar energy and air source heat pump integrates two technologies of solar heating and air source heat pump,which can complement each other to achieve efficient and all-weather operation of the heating system.The air source heat pump uses air as a source of cold and heat,and requires only a small amount of electrical energy input to achieve the purpose of cooling or heating the building,which is beneficial to the efficient use of resources and sustainable development.The temperature difference between day and night in Tibetan areas is large,and the winter temperature in western Sichuan is low and the humidity is high.The heating efficiency ratio of the air source heat pump is rapidly attenuated due to low temperature and frosting.These factors limit the application of air source heat pump;However,the Tibetan areas and western Sichuan is rich in solar energy resources,providing good resource conditions for solar energy utilization and air source heat pump combined heating system.In the combined heating system,the heat pump unit mostly adopts the traditional temperature difference control method,that is,the start and stop control of the heat pump unit is simply realized by the change of the water temperature of the water tank.Air source heat pumps operate on low temperature and high humidity nights,and their COP decays due to low temperature and frosting problems.For the combined heating system,the heat pump can avoid the low temperature frosting area as much as possible,and operate in the efficient period to store the heat in the water tank by adopting a reasonable operation strategy.Before improving the operation strategy,the capacity matching of the main equipment of the combined heating system must first be carried out,including the selection of the solar collector area and the air source heat pump capacity,and the design of the storage tank volume.How to combine solar hot water heating and air source heat pump to ensure that the combined heating system is as economical and stable as possible is an urgent problem to be solved.In this study,the capacity matching and operation optimization model of solar energy and air source heat pump combined heating system is proposed,and the genetic algorithm is used to solve the problem,mainly to complete the following work:1.The working principle of the system is analyzed,and the influencing factors of the combined heating system are analyzed from three parts: solar collecting system,air source heat pump unit and building heating load.2.The main component models of the system are established,and based on this,the models for capacity matching and operation simultaneous optimization of the combined heating system are developed.3.Taking the minimum life cycle cost of the combined heating system as the objective functions,and the collector area,air source heat pump capacity,tank volume,and heat pump start-stop temperatures and start-stop temperature difference as the decision variables.The MATLAB software is used to mathematically model the combined heating system,and the genetic algorithm is adopted for simultaneous optimization.The capacity matching and operation strategy optimization results of the combined heating systems in each region are obtained.4.The single capacity matching and single operation optimization of the combined heating system are carried out to compare and analyze the limitations of the conventional optimization method,highlighting the advantages of capacity matching and operation strategy simultaneous optimization method.Based on the problem of frosting and defrosting of air source heat pump,this paper comprehensively considers the system capacity and heat pump operation strategy,and optimizes the capacity parameters and operating parameters of solar energy and air source heat pump combined heating system.Except for the Lhasa area,while saving system life cycle costs,the system COP has improved in all study areas,indicating that the optimization method of this study can well solve the problem of capacity matching and operation optimization in actual engineering.The comparative study shows that the energy saving effect of the single operation optimization of the system is obvious;In order to further tap the energy saving potential,the capacity parameter,which is the most closely related to the operation of the heat pump,is included in the operation optimization,and the energy saving effect is remarkable,which makes the combined heating system more economical and energy-saving.The comparison result further confirms that there is an interaction between the capacity parameters and the operating parameters,and the separate optimization is limited.