Impacts of geometric factors on the hydrothermal characteristics in a shell and cone-shaped coil heat exchanger

Abstract

Cone coils have a larger surface area and produce more turbulence, which enhances the heat exchange rate, making them a more efficient option for improved heat transfer than simple coils in shell-and-coil heat exchangers. In addition to reducing fouling and the requirement for maintenance, the cone shape may also provide the benefit of a self-cleaning action. Ensuring a more even flow distribution maximizes the heat exchanger's surface area use and reduces poor-flow zones. Applications needing compact solutions without compromising performance significantly benefit from this design's versatility, allowing customization to meet unique operational demands. This work evaluates numerically the impact of employing a cone-shaped coil tube in a shell-and-coil tube heat exchanger, considering various configurations and coil pitches. A commercial CFD code is used to perform the numerical simulations based on the finite volume approach. The present study has two sections. In the first part, three different coil configurations were considered. The best case was considered according to the numerical results obtained from the first section. Then, in the second part, the impact of the cone coil pitch on the hydrothermal characteristics was analyzed. The obtained numerical outcomes revealed that the best performance evaluation criteria factor belongs to the cone-shaped coil with divergent configuration by about 64.1 % and 57.45 % more than the cone-shaped coil with convergent configuration at De = 1,000 and De = 2,500, respectively. Moreover, the cone-shaped coil with a divergent configuration displayed higher JF values by approximately 61.54 % and 58.06 % than a cone-shaped coil with a convergent configuration at De = 1,000 and De = 2,500, respectively. Among different evaluated cone coil pitches, the maximum performance evaluation criteria factor belongs to the case with pitch values of 40 mm. Moreover, the JF value increases by approximately 4.76 % and 5.56 %, respectively, at De = 1,000, when the pitch value grows by around 60 % and 100 %. Furthermore, when the pitch value climbs by 60 % and 100 %, at De = 2,500, the JF value rises by roughly 12.16 % and 19.59 %, respectively.