Sensitivity Analysis on Thermal Performance of Gas Heater with Finned and Finless Tubes using Characteristics-based Method

Document Type : Original Article


1 School of Mechanical Engineering, University of Tabriz, Tabriz, Iran

2 School of Mechanical Engineering, University of Bonab, Bonab, Iran

3 School of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran


Natural gas must be preheated to prevent phase change and gas hydrate in pressure reduction stations. This paper aims to investigate the effect of the fins of gas tubes and their configuration, arrangement, and shape on the heat transfer and thermal efficiency of gas. To conduct a parametric study, two tube cases with fins and without fins, and in the finned case for the fin’s configuration, two longitudinal and circular arrangements, and the formation of the fins, two solid and interrupted forms were analyzed. Also, three types of cross-sections, including rectangular, convergent parabolic, and divergent parabolic, for the shape of the fins have been studied. For this simulation, the three-dimensional, incompressible, and steady flow was considered, and for analysis and discretization of convective heat equations, the characteristic-based method was applied. FORTRAN software was also used to implement and solve the equations. The results show that in solid and interrupted fins and increasing the number of fins in parallel, the dimensionless heat transfer coefficient increases. Also, the dimensional heat transfer coefficient decreases with increasing the ratio of fin height to the tube’s diameter. Also, the most significant heat transfer improvement was related to the divergent parabolic cross-section.


transfer coefficient increases from 8 to 18% due to using solid fins, from 7 to 16% due to the use of interrupted fins, and from 10 to17%, and 8 to 15% due to the use of 4 and 2 blades, respectively. Increasing the ratio of fin height to tube diameter, the presence of the fin, acts the role of heat trap and prevents the flow motion. Hence, H/D has the most significant improvement on heat transfer, and with increasing Rayleigh number, its effect also increases. Among the three cases selected for fin height, H=15 mm has the highest Nusselt increase. The highest heat recovery parameter is related to the divergent parabolic cross-section. Despite the high-pressure drop, increasing the heat transfer coefficient leads to the maximum heat recovery parameter. It shows that the improvement of the heat transfer coefficient overcomes the increase of the coefficient of friction, and the application of the fin is justified from the optimization point of view.
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