Airside thermal–hydraulic performance evaluation of flue gas coolers for waste heat recovery

Abstract

H-type finned tubes and integrally-molded spiral finned (IMSF) tubes are widely used in flue gas coolers for waste heat recovery, but it is difficult to design an efficient flue gas cooler in actual engineering by experience due to lack of a general factor to evaluate the thermal–hydraulic performance of different types of finned tube heat exchangers. Based on the correlations of the Nusselt Nu, the Colburn factor j, the friction factor f and the ratio Q/Wp, this paper proposed a comprehensive performance evaluation method to evaluate the thermal–hydraulic performance of different types of finned tubes, which includes the power consumption goodness factor (FQ/W) and volume goodness factor (FQ/V). The reliability of the evaluation method was verified through real engineer design. The thermal–hydraulic performance of the H-type finned tube bundle and IMSF tube bundle was obtained through computational fluid dynamics simulation using periodic physical models, and evaluated using the general evaluation method. The results show that the power consumption for H-4 and IMSF-3 is almost identical with the same heat transfer rate, but the compactness of IMSF-3 is better than that of H-4. The findings can guide the design and optimization of flue gas coolers.