A Simple Solution for Heat Transfer in a Triple Tube Heat Exchanger

Abstract

Triple tube heat exchangers in general perform better when compared to double tube heat exchangers, mainly because they improve the heat transfer due to the passage of additional fluid and also of its larger heat transfer area per length unit. Nevertheless, for triple tube heat exchangers, the analytical solutions available in the literature are limited to specific boundary conditions or are cumbersome. Therefore, this work aims to obtain a compact form of the analytical solution, suitable for co-current and counter-current flow arrangements. The solution form is developed based on a solution from literature for a co-current moving bed heat exchanger model, through analogies with triple tube heat exchangers. From the solution form, explicit expressions for the crossover points are also obtained. For a better understanding of the underlying physics, a scale analysis is performed. When compared to experimental data and more complicated solutions from literature, the obtained results presented good agreement.