CFD analysis of an economizer for heat transfer enhancement using serrated finned tube equipped with variable fin segments

Due to the extensive use of heat exchangers in various daily and industrial applications, the improvement of their performances is of great importance. It is evident from the literature that very limited work has been done in serrated finned tube economizer for heat transfer enhancement and pressure drop performance. This paper deals with the heat transfer improvement and pressure drop performance of helical serrated finned tube bundles in inline bare tube counter cross-flow water tube boiler Economizer, which has larger heat transfer area and higher heat exchange efficiency. Numerical simulation on heat transfer performance is carried out on 116.3 TPH of MCR boiler unit, one tube row with three-row finned tube passes; helically wound fin geometries of partially serrated finned tubes are investigated. A steady-state approach, with two-equation, a k-ε turbulence model is employed to examine the effect of Reynolds number in the range of 8000 to 20000. In this study the conjugate heat transfer is considered for the calculation of the conduction in a solid region is coupled with the calculation of the temperature distribution in the working fluid flowing over or through this solid region. The effect of a number of serrated segmented finned tubes per period on the performance of heat transfer enhancement is also investigated. The computational results fall within the range of values predicted by empirical correlation. The results show that the heat transfer is enhanced by up to 3.53% to 5.14% if the number of segments per period varied from 20 to 50.