Cpc Heat Pipe Vacuum Tube Collector Heat Transfer Model Analysis

CPC heat pipe evacuated tubular collector was studied in this thesis. The system equation of the compound parabolic was obtained, the solar radiation absorption model of the compound parabolic and the heat transfer model of the heat pipe evacuated tubular were constructed. The relationship of the instantaneous collector efficiency of CPC heat pipe evacuated tubular collector and the temperature difference of the fluid was solved.Firstly, the current situation of the energy development and the advantages to exploit solar energy in China were briefly introduced, the heat utilization condition of the solar is also expounded, which is the basis of this study. CPC heat pipe evacuated tubular collector integrate the compound parabolic and the heat pipe evacuated tubular technology, as an innovation, the separated type heat pipe was used in the heat pipe evacuated tubular in this paper. The other innovation is that the selective coating was covered on the surface of the heat pipe and the fins, not on the surface of inner tube of the evacuated tubular as before.Secondly, according to the location of Hangzhou, the solar radiation intensity in Hangzhou was obtained, and it is obvious that the solar radiation of July is the strongest in Hangzhou, Hourly average intensity of solar radiation reaches 819.63 W/m~2 in every month. The daily average sunshine which is the longest time in a year is 13.95h. According to the compound parabolic structure of CPC heat pipe evacuated tubular collector, the installation location and the heat transfer theory, the solar radiation absorption model was established. Then the amount of solar radiation of the receiver in CPC heat pipe evacuated tubular collector in July in Hangzhou was calculated.Finally, according to the basic principles of heat transfer, the heat transfer model of heat pipe evacuated tubular was proposed. For the heat pipe evacuated tubular, because it is vacuum between the inner and the outer tube, the convection and conduction can be neglected, but there is convective and radiation for the inner tube of the evacuated tubular and the heat pipe. The heat transfer model of CPC heat pipe evacuated tubular collector was studied, then the instantaneous collector efficiency equation was obtained through the optical analysis and heat transfer analysis for the collector, as well as the relationship of the instantaneous collector efficiency of CPC heat pipe evacuated tubular collector and the temperature difference of the fluid. The evaporation section of the separated type heat pipe is vertical, when the forced convection boiling is occurred in the heat pipe, the process is very complicated, what we can do is to fit the corresponding boiling heat transfer relationship according to the previous experimental data.The calculated results indicated that CPC heat pipe evacuated tubular collector fully played the advantages of enhancing energy density after focusing, meanwhile it is easy to combine with the construction in Hangzhou, therefore there will be great potential for CPC heat pipe evacuated tubular collector in the future.