Heat transfer analysis of a new volumetric based receiver for parabolic trough solar collector

Effective use of selective absorbing coating in surface based receivers and nanofluids in volumetric based receivers for better thermal performance have been confirmed in previous studies. However, in practical application, these receivers suffered from the problem of performance degradation after long-term high-temperature operation, and they were high-cost. This study proposed a novel kind of parabolic trough receiver by locating the absorber tube inside heat transfer fluid (HTF) in a twin glass tube, and developed its mathematical heat transfer model. Based on this model, the novel receiver was verified to be desirable when the inlet temperature of HTF was lower than 150 °C (with an efficiency sacrifice within 4%), and particularly in the range of 100-120 °C (with an efficiency sacrifice within 1.5%). Strategies including replacing the selective absorbing coating with non-selective absorbing coating, lowering the velocity of outer HTF and lowering the emissivity of the inner glass tube were investigated and verified to be effective in specific conditions.