Currently, parabolic trough is the most widely used and most mature technology of concentrating solar power(CSP) generation. Molten salt is becoming the first choice for heat transfer and heat storage medium of CSP plants because of its high operating temperature, high cycle efficiency and low price. However, the high freezing point of molten salt is usually 120～220 ℃, which puts the piping system at risk of freezing. This work focuses on advances in the research and application of thermal loss characteristics of piping system and strategies for salt freeze prevention and recovery, including the heat transfer and thermal loss performance prediction of receiver tube, the insulation optimization of molten salt process pipeline, the freeze protection schemes during shutdown condition at night, and the method of recovering from a freeze event in a molten salt parabolic trough solar field. Moreover, some suggestions have been proposed for the further research work, such as much more efforts should be made to eliminate the risk of solidification and freezing of molten salt while reducing the operation and maintenance cost of freeze protection and recovery system to the minimum. This work is also available for reference to other CSP systems such as linear Fresnel and solar tower plants using molten salt as heat transfer/heat storage medium.

photothermal power generation;molten salt;parabolic trough;thermal loss;freeze protection;thawing;electric heat tracing