Process Performance Analysis Of Heat Pipe Solid Surface Heat Collection And Storage

The high energy consumption and large carbon emissions in China’s construction operation stage will seriously restrict the realization of carbon neutralization and carbon peak targets.So building energy-saving capacity has attracted more and more people’s attention,and solar energy for building is an effective solution.Solar energy is the source of natural energy,it is relatively cheap and easy to use,large-scale use can effectively reduce the use of conventional energy.In this paper,the copper-water heat pipe is used as a heat transfer element,and it is embedded in the solid surface such as concrete to construct a new type of solar heat pipe solid collector.Through the method of combining theory,experiment and simulation,the heat collection and heat storage process of solar heat pipe solid collector system,the effect of influencing factors of heat collection process and the law of heat collection performance are studied,which lays a theoretical foundation for the practical application of solar heat pipe solid collector.Firstly,the heat transfer process of heat pipe is analyzed,and the equivalent thermal conductivity and theoretical thermal conductivity of heat pipe are compared by theoretical analysis and experimental analysis.It is found that the equivalent thermal conductivity and theoretical thermal conductivity of the heat pipe increase with the increase of the adiabatic section length of the heat pipe.When the adiabatic section of the heat pipe is 250 mm,the equivalent thermal conductivity and theoretical thermal conductivity of the heat pipe reach the maximum value.At the same adiabatic section length,the equivalent thermal conductivity of the heat pipe increases and then decreases as the ratio of the evaporating section to the condensing section increases,reaching a maximum at a ratio of 1,and the maximum value of the equivalent thermal conductivity is5.6×10~4 W/（m?K）,which is much higher than the thermal conductivity of existing metals.Secondly,this paper builds an experimental system for the heat collection performance of heat pipe solid collectors.Through experimental analysis,the effects of heat pipe number,collector surface form,wind speed and radiation intensity on the collector performance of heat pipe solid collector were studied.It has been found that increasing the number of heat pipes and reducing the distance between heat pipes can improve the collector’s heat collection and instantaneous heat collection efficiency.When the number of heat pipes is 7,the maximum instantaneous heat collection efficiency of the collector is 46%.At a radiation intensity of 963.2W/m~2,a collector of 0.16m~2 within 2 hours produces 357.79 k J.By studying the effect of collector surface state（i.e.laying stones with different sizes）on the heat collection and heat collection efficiency of the collector,it is found that when the particle size of the stone is 15 mm,the heat collection effect is better,and the maximum heat collection is 522.54,and the peak instantaneous heat collection efficiency is 67%.As the radiation intensity rises the heat collection capacity of the collector also rises,but after the radiation intensity reaches 963.2 the heat collection capacity no longer rises.Wind speed has the greatest impact on collector performance compared to other factors,with the amount of heat collected and the peak of instantaneous heat collection efficiency decreasing gradually for all collectors as wind speed increases,and collectors without stone cover are the most affected.Thirdly,based on the analysis of solar radiation process,heat pipe solid collector collector process,water tank heat storage process and inclined surface radiation theory,the corresponding simulation modules are built by simulink,and the solar heat pipe solid collector heat storage system is constructed.Taking Changchun area as an example,the performance of solar heat pipe solid collector heat storage system is analyzed.It was found that the effect on the collectors diminished as the wind speed increased,with negligible effect when the wind speed reached 5.5 m/s.The instantaneous collector efficiency first increases and then decreases,and then increases and then decreases again.The peak collector efficiency on July 17 is 34%,and the daily average collector efficiency is maintained at about 30%.For Changchun,the optimal inclination angle and azimuth angle of the heat pipe solid collector during the working period are 20°and 0°,respectively.At this angle,the total heat collection of the collector in the middle of a year（April–September）is 6229 MJ.Finally,the paper analyses the economics of heat pipe solid collectors in the Changchun area during operation using a constructed heat pipe solid collector storage system.The study found that a 3m~2 collector could save 908 RMB per year,for a total lifetime energy saving of12,745 RMB and a total carbon reduction of 10.65 t.This shows that the heat pipe solid collector can play a role in energy saving,cost saving and carbon reduction to a certain extent.