Technology Of Multi Energy Coupling Heating Based On Solar Energy And Water Source Heat Pump

Resource and industrialization of solar energy are both abundant in China.With the improvement of building energy-saving in recent years,solar heating technology is energetically popularized.This paper is based on National Key R&D Program of China and the demand for clean heating in the north.Through the research on multi energy coupling heating technology,Problems in conventional solar heating system and multi energy complementary heating system will be improved.The available temperature range of collector in conventional solar heating system limits the utilization of solar energy.The combination of solar energy and water source heat pump can make full use of the solar energy at low temperature and reduce the average collector temperatur,so as to improve the collector efficiency.Besides,the COP of water source heat pump will also be maintained at higher value through control technology.By theoretical modeling and simulation calculation,when heating consumption and solar collector,storage tank and other equipment configuration,as well as basic control strategy are all same.the heat gain of solar energy in multi energy heating system has increased by 54.7%,and average collector efficiency is raised from 33.4%to 52%compared with conventional solar heating system.This paper takes an existing rural housing in Beijing as heating object to develop multi energy experimental system.The equipment,pipeline,accessories and automatic control system are highly integrated.Software that is easy to master and operate is developed.The measured result shows that when solar radiation is 17 MJ/(m~2·d)and ambient temperature is2.5?,the heat gain of solar energy can reach 9.5 MJ/(m~2·d)and COP of the heat pump maintains in 4.0~4.3 stability.In cloudy(haze),sunny,cloudy,and high ambient temperature conditions,the solar collector efficiency of the system can reach 48.3%,56.2%,37.4%and42.1%respectively.Besides,the accuracy of system calculation model is verified by the measured data.The configuration optimization of multi energy heating system is proposed.The standard stagnation temperature calculation model of plate collector can be used to optimize the heat resistance and pressure resistance of system.According to the mechanism of spiral coil heat exchanger,the values of heat transfer under different tube lengths,pipe diameters and wall thickness are calculated,so as to construct the selection and optimization chart.By the performance-based optimization method,the optimum collector angle is obtained,and the recommended value for flow rate in collector is given.The influence of collector area and water tank volume on solar energy utilization is also analyzed.Taking the energy-saving residential building in Beijing and Lhasa as the heating object,we have formed the configuration scheme of collector area and storage tank volume.The optimization of multi energy heating control system is proposed.Through calculation and experiment,this paper summarizes the collector outlet temperature algorithm and collector inside temperature algorithm.Temperature stratification characteristic in tank is analyzed by CFD for optimizing how to select the lower temperature and starting temperature difference in solar system control,as well as heat extraction from tank,living hot water storage,usage of coil heat exchanger and auxiliary heat source.This paper tries to adjust the control temperature of the auxiliary heat source to improve the solar energy utilization without changing heating quality.Heat source supply temperature is controlled by regulating bypass flow with PID method.Discrete PID computing model is established to improve the precision of temperature control.After optimizing the switching process of heating modes,the switching time is reduced and the indoor temperature is more stable.Finally,by improving the heating cycle control,the power consumption of heating equipment and distribution system is further reduced and stability of system is improved as a whole.