Application Research On Air-source Heat Pump And Low-temperature Heat Power Generation Technology In Solar Heating

Aiming at the energy and environment problems caused by building heating in northern China and taking the opportunity of vigorously developing renewable energy,this paper carried out theoretical and experimental research on key scientific issues of the air-source heat pump technology and solar low-temperature heat power generation technology,which based on the basic principles of energy upgrading and conversion that are two key technologies for low-grade thermal energy utilization.Then,a cogeneration system of heating,power and cooling using air energy and solar energy was proposed to realize clean heating in winter and efficient cooling in summer.At the same time,the system can use the low-temperature hot water,produced in solar collectors during non-heating period,to generate electricity for building use and optimize the energy structure of building.Firstly,combining with the methods of energy,exergy and economic analysis,and directly correlating the thermal cycle parameters of the system with the structural parameters of the heat exchangers,the technical and economic evaluation models of the air-source heat pump system and solar low-temperature heat power generation system were constructed,which provide theoretical basis for the working fluid selection and performance optimization of the system.Based on the thermo-economic model of air-source heat pump system and considering the thermo-economic performance,pressure bearing capacity,working fluid charge and its environmental protection characteristics,the low-temperature adaptability of the air-source heat pump system,which respectively uses the non-azeotropic mixed working fluids BY-2A,BY-2B,BY-2C independently developed or R22,R410 A regularly used in commercial units,was evaluated and verified by experiments in cold or severe cold regions.The results showed that the air-source heat pump system with BY-2A,BY-2B,or BY-2C exhibits superior heating performance under low-temperature environment.Compared with the R22 system,their heating capacity can be increased by 10.68%,28.01% and 65.66% respectively.Based on the thermo-economic model of the solar low-temperature heat power generation system,the qualitative and sensitivity analysis of the influence of main design parameters on the system performance was carried out to provide a theoretical basis for the initial design and performance optimization of the system.Then,taking the payback period of system investment and the net profit of the whole life cycle as the evaluation indices,the multi-objective and multi-parameter parallel optimization method was proposed to determine the optimal design parameters of the solar low-temperature heat power generation system.Besides,a small-scale low-temperature heat power generation plant was built,and the influence of the main design parameters on the performance of the power generation unit was conducted under the optimal matching operation effect of the system components.Finally,a cogeneration system of heating,power and cooling using air energy and solar energy integrating the solar heating,air-source heat pump and organic Rankine cycle solar low-temperature heat power generation technology was proposed,and its suitability for office buildings in Tianjin and Shenyang was analyzed.The results showed that the reasonable implementation of the cogeneration system will bring tremendous energy efficiency,economic and environmental benefits,especially in Shenyang.Compared with the conventional cooling and heating source system,the payback period of the system investment is as low as 2.70 years,and the primary energy ratio can reach 2.71.