Testing And Research On Thermal Performance Of Vacuum Transfer Tubes With Solar Thermal Power Plant

Solar thermal power generation is a very effective method for solving a series of problems of energy depletion and environment pollution. In other countries, especially Europe and America, solar thermal power technology are researched relatively early. They are entering rapid developing stage of commercial operation. In recent years, in order to meet the rapid growth of China’s energy demand, but also to ease the pressure on the environment and achieve sustainable development, China will also be bound to enter the rapid development period of solar thermal power. Currently parabolic trough solar thermal power technology is the ripest and it has rich operational experiences and achieved commercial operation.Early in the world parabolic trough solar thermal power plants generally use thermal oil as the heat transfer fluid. However in recent years, some exporters begin research that water and molten salt are used heat transfer fluid in order to improve plant efficiency and reduce costs, meanwhile some demonstration power plant are in construction. But all of them must solve two problems:firstly,they will be freezed. Secondly, a large pipeline transportation system has a lot of heat loss. Therefore it is very important that a good insulation material is used to protect pipeline transportation system. Because it not only keep the whole power plant safe but also increase economic efficiency.By building a steady-state heat loss test platform,we test equivalent thermal conductivity of vacuum transfer tubes that developed by the HuBei Salnner Vacnnm Science And Technology Co.,Ltd.The experimental results found equivalent thermal conductivity of the vacuum transfer tube is between 0.00903 and 0.016913 W/m·℃ when the inner tube wall temperature is from 200 to 500 ℃. At the same time, equivalent thermal conductivity of the vacuum transfer tube is also measured under field conditions in Delhi "1.6MW parabolic trough demonstration power plant " of CGN Solar Energy Technology Co., Ltd. It found the thermal conductivity is ranged between 0.0111 and 0.0191 W/m·℃ when the inner tube wall temperature is from 100 to 320 ℃.It is slightly higher than steady-state test results. And finally a steady-state model is builded for simulating heat transfer of vacuum transfer tubes and calculate the equivalent thermal conductivity.It found it is between 0.003073 and 0.010549 W/m·℃.we found the equivalent thermal conductivity of vacuum transfer tubes is far lower than the thermal conductivity of traditional insulation materials.