Optimization Of Graphite-filled Heat-pipe Evacuated Tubular Solar Collector

The thermal performance of the solar heat collector is vital to the utilization of solar resource. Heat pipe evacuated tubular solar collector has good thermal performance and high collecting temperature, and has important significance for develop and research.A new type of graphite-filled evacuated tubular solar collector is proposed based on the existing type of heat pipe evacuated tubular solar collector. Graphite has a high conductivity coefficient and prior contacting performance and can increase the thermal performance of the collector effectively. To study the thermal performance of the graphite-filled heat pipe evacuated tubular solar collector, a physical model and a one-dimensional steady-state heat transfer mathematical model of the graphite-filled heat pipe evacuated tubular solar collector is built. The calculation method of the heat loss coefficient and the efficiency of graphite-filled type, ribbed type and conduction oil type is respectively proposed, the solution is made and analyzed in comparison. For prediction of the performance of the graphite-filled heat pipe collector, a simulation model is built by simulation software and the output energy, outlet temperature and the instantaneous efficiency are obtained.The results show that the graphite-filled heat pipe evacuated tubular solar collector has a good heat transfer performance, with an efficiencyup to 65.8%, higher than the ribbed type and the conduction oil type by respectively 11% and 7%. From the spring equinox day to the winter solstice day, it can generate steam for 3.5~10 hours per day.