Numerical study on the effect of inner tube fouling on the thermal performance of high-temperature fin-and-tube heat exchanger

摘要

The paper presents the numerical study on the influence of inner tube surface fouling on the thermal performance of a high temperature fin-and-tube heat exchanger. The heat exchanger is used to cool down the hot flue gas. In order to simplify the heat transfer model, only the gas flow through the passage formed by the six consecutive fins is analysed. Fouling on the inner surface of the tube wall in a form of scale can cause large decline in heat transfer ability. Since the gas in the outer space is, then, not cooled efficiently, the temperature on the outer wall can increase, even above the allowable strength limits. Because the gas flow path through passages formed between fins is complex, the CFD simulations were conducted in order to determine the velocity and temperature variations for flue gas flow in the inter-tubular space of a cross-flow heat exchanger. The total heat transfer rate, outlet gas temperature and the maximum temperature of tube wall for various gas inlet velocities were determined.