A review on dryout and Post-dryout heat transfer inside tubes and tube bundles

Abstract

• Detailed review on dryout mechanism and dryout and post-dryout heat transfer. • Summarizing the dryout criterions and models of dryout and post-dryout heat transfer. • Elaborating the methods of dryout and post-dryout heat transfer enhancement. • Proposing further research suggestions of dryout and post-dryout heat transfer. The working medium changes from subcooled liquid through flow boiling to superheated vapor in actual once-through thermal equipment (such as once-through steam generators, once-through boilers). Dryout heat transfer deterioration inevitably occur in this vapor-liquid two-phase flow and heat transfer process. After dryout occurs completely, vapor almost completely covers the wall, resulting in a rapid deteriorating heat transfer performance and a sharp rising wall temperature, which puts forward higher requirements on the design, manufacture, and operation of the equipment. The mechanism of dryout is elaborated, and the dryout criterion is summarized in this paper. The three methods that are used to describe the mathematical model of dryout and post-dryout heat transfer are arranged, and the dryout and post-dryout heat transfer in the straight channel is introduced. Furthermore, the methods of enhancing dryout and post-dryout heat transfer are introduced such as changing the geometric structure (including changing the shape of the flow channel and processing the surface of the flow channel) and injecting liquid droplets, etc.