Upgrading the performance of a new shell and helically coiled heat exchanger by using longitudinal fins

Abstract

Shell and helically coiled tube heat exchangers are comprised of curved tubes inside a shell and they are usually utilized in different sectors such as refrigeration systems, chemical processes, food industry, heat recovery systems and thermal storage systems. Improving the efficiency of heat exchangers could result in improve in the total performance of energy systems. The main purpose of the present research is to specify the effect of adding fins over helically coiled tube on thermal performance of a horizontal shell and helically coiled tube heat exchanger. In the first step of this study, CFD method was utilized to simulate finned and finless heat exchangers and determining the influence of adding fins. In the next step, manufactured finless and finned heat exchangers were tested experimentally. CFD simulation and empirical results of the present work exhibited the positive effect of integrating fins on the coil. Integrating fins over the helically coiled tube led to increase in turbulence intensity and consequently improved the heat transfer. The effectiveness of finned and finless heat exchangers was attained between 0.59 and 0.93. Integrating fins led to obtain an average improvement of 10% in the heat transfer coefficient. Furthermore, adding fins led to achieve a mean improvement of 10.6% in the overall heat transfer coefficient. While, the highest improvement in the overall heat transfer coefficient obtained as 15%.