Simulation Study on Heat Transfer Conditions Based on Vertically Descending Evaporating Tubes

This paper aims to investigate the heat transfer conditions of vertically descending evaporator tubes. Through numerical simulation methods, the flow patterns and heat transfer characteristics within the evaporator tubes under both uniform and abnormal heating conditions are analyzed. Fluent software is employed to simulate the normal evaporation process in uniformly heated evaporator tubes, exploring their gas circulation and local heat transfer conditions. Additionally, simulations are conducted for descending evaporator tubes under abnormal heating to analyze the impact of different heat distributions on the flow patterns and heat transfer within the tubes. The conclusion drawn is that the primary cause of working fluid descent in evaporator tubes is uneven heating of the tube bundle. A single evaporator tube forms a stable circulation, whereas an increase in the number of tubes in the bundle exacerbates the descent phenomenon. To prevent such occurrences, measures such as optimizing heat transfer, ensuring complete combustion, and regularly maintaining the pipelines can be implemented. Future research could further simulate real-world boiler heating conditions and explore the application of two-phase evaporation flow in other equipment.