| Solar energy is a renewable and eco-friendly energy source,but its instability and seasonality limit its use in heating.In contrast,air source heat pumps operate relatively stable,but their heating performance will decay at low ambient temperatures,so that they cannot meet the heating demand.Combining solar energy and air source heat pump can effectively overcome the limitations of each individual system.While there are various forms of solar-air source heat pump coupling systems,they can essentially be classified into two types:series and parallel.The series type has obvious advantages under low ring temperature and low radiation,and the parallel type has obvious advantages under high ring temperature and high radiation.However,for the more common middle-ring moderate radiation,neither of them is the optimal scheme.The research group previously proposed the cascaded scheme of solar energy and double-stage compressed air source heat pump,which obtained the optimal operation effect under the moderate and medium radiation of central and middle ring.However,the application of the cascaded scheme in quasi-two-stage compressed air injection enthalpy heat pump systems and water tank heat storage has not been extensively researched.This paper utilizes a combination of experiments and simulations to conduct an in-depth investigation of this issue.The main objectives are as follows:(1)After analyzing the characteristics and limitations of existing solar energy and air source heat pump integrated systems,we propose a regenerative solar energy hybrid assisted enthalpy injection air source heat pump system.This system incorporates a solar collector and heat collector into the intermediate air injection branch of the air source heat pump.Auxiliary heating is performed between the two stages of quasi-two-stage compression to increase air injection volume and enhance enthalpy injection.This section describes the analysis of the characteristics and working principle of the new system,the design of two water tank operation modes,and proposed evaluation indexes for the solar energy and air source heat pump subsystems,as well as the integrated system.This analysis lays the foundation for future experimental and simulation research.(2)Building on the proposed technical scheme for the new system,we design and construct an experimental platform for a thermal storage type solar hybrid auxiliary jet enthalpy heating air source heat pump system.experimental system consists of a solar hot water subsystem,jet enthalpy heating heat pump subsystem,data acquisition system,and control and regulation system.After debugging each subsystem to ensure the accuracy and reliability of measurement,under the outdoor temperature condition of-13℃,the control of different intermediate air path heat extraction,the"solar energy+EVI"mode of experimental test,analysis of different air path heat extraction on the compressor exhaust pressure and temperature,system heat production and COP.(3)To conduct simulation research on the new system,it is necessary to build an accurate and reliable system model.First,Sketch Up software was used to build the physical model of the target building,and TRNSYS software was imported to simulate the heat load of the heating building hour by hour to obtain the dynamic load instantaneous data.Then the mathematical model of each part of the system is constructed.The compressor model is programmed by MATLAB software,and the model of other parts is programmed by TRNSYS software module.According to the characteristics of the system,the control strategy of heat extraction in the air passage and the start-stop control strategy of room temperature and heat pump are proposed.The TRNSYS software platform is used to connect all components according to their logical relationships,forming the system model.The accuracy of the heat pump sub-model and integrated system model is verified using experimental data,laying the foundation for further system simulation research.(4)The impact of different operation modes,collector area,water tank volume,and maximum heat extraction of the air jet on the operational performance of each subsystem and integrated system is studied based on the system model.The optimal system matching and operation strategy are analyzed and determined,and the optimal system is evaluated from the perspectives of energy efficiency,economics,and environmental protection.The results show that for the 100m~2office building in Jilin area studied in this paper,the optimal configuration of the integrated system is a 500L heat storage water tank,7.5m~2flat plate collector area,and a maximum heat extraction of 6000W for the air jet.The optimal operation mode is a storage-type system.Compared with traditional air source heat pumps,the optimal system can save energy17.53%,reduce emissions 15.56%,and have an investment payback period of about 6.11 years.Therefore,the integrated system studied in this paper has significant advantages and a very broad application prospect.It is beneficial to promote the application of solar energy and air source heat pumps in cold and severe cold regions,and it is of great significance to promote the popularity of clean heating and achieve the"dual carbon"goal. |
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