Heat loss of parabolic trough evacuated tubular collector

Mathematical model of radiation and residual gas convection heat transfer from absorber to glass envelope, convection and radiation heat transfer from glass to ambient was established, the calculation method of the model was also proposed in this paper, and the accuracy of the model was verified by comparing with experimental results. Several major factors that can influence heat loss were analysed using this model. The results show that the heat loss is much more when the absorber temperature is higher; lower ambient temperature and higher wind speed will cause more heat loss, but not very much; the emittance of the selective coating is a key factor to heat loss; vacuum level will also influence heat loss a lot.