Investigating the Effect of Cross-Section on the Performance of Conical Coiled Tube Heat Exchangers by Computational Fluid Dynamics

It is significant to determine the optimal dimensions of the heat exchangers to reduce energy consumption. The helical tube heat exchanger is widely used in industry due to its advantages over other types. Therefore, investigating this type of heat exchanger can be an interesting topic. In this research, conical coil tubes with circular, elliptical, and square cross-sections with 10, 30, and 50° cone angles and 15, 30, and 45 mm pitch were modeled by computational fluid dynamics to evaluate the thermal-hydrodynamic performance. The data relating to the Nusselt number and friction factor for all investigated geometric shapes were compared and analyzed. The results showed that the elliptical cross-section tubes have better heat transfer performance compared to other geometries. The results showed that the elliptical cross-section has a better heat transfer performance compared to the square and circular cross-sections by 34.33% and 0.38%, respectively. Moreover, the lower values of the Nusselt number and the friction factor were obtained for the square cross-section due to the change in the thickness of the boundary layer.