Case Studies in Thermal Engineering (Mar 2024)
Using different geometries on the amount of heat transfer in a shell and tube heat exchanger using the finite volume method
Abstract
This research investigates the heat transfer and pressure drop characteristics of a conical spiral tube heat exchanger. The study specifically focuses on the application of Ag-HEG (Silver–Hydrogen exfoliated graphene) nanofluid and various turbulator designs. The range of Dean Numbers, specifically 2200 < Dean <4200, was studied through experiments under turbulent flow conditions. Furthermore, the finite volume method-based ANSYS Fluent commercial code was utilized for numerical simulations. Additionally, numerical simulations were performed using the ANSYS Fluent software, which utilizes the finite volume method. This research aims to perform a numerical analysis on the efficiency of a conical shell and tube heat exchanger. When compared to other models, spiral heat exchangers provide a larger contact area between the fluid and the exchanger within a specified occupied area. This advantage is one of the prominent features of this particular type of heat exchanger. The simulations were conducted in two stages. During the first stage, the thermal performance coefficients of three turbulators were evaluated. In the second stage, the four-blade turbulator with ten revolutions, which exhibited superior thermal performance, was further analyzed based on the number of circles around the center of the conical spiral coil. The numerical results showed that the four-blade turbulator with ten revolutions displayed superior thermal performance compared to the other modes, specifically the two-blade and three-blade turbulators. In the second stage, it was found that the Nusselt number achieved from 30 revolutions was higher by 4.2 %, 10 %, and 18.3 % compared to the Nusselt numbers obtained from the other two modes of 10 and 20 revolutions. Consequently, it is concluded that utilizing Ag-HEG nanofluids in conjunction with the four-blade turbulator featuring 30 revolutions is the optimal choice for improving heat transfer in conical spiral tube heat exchangers while maintaining an acceptable level of pressure drop. This combination outperforms traditional fluids and turbulators.
