CFD Modeling of Flow and Heat Transfer Processes in a Cooler for Sampling from an Airlift Fermenter

Abstract

The article deals with CFD modeling of fluid flow in a cooler designed for sampling from an airlift fermenter. The authors focused on the hydraulic and thermal analysis of a tube-in-tube cooler. Boundary conditions and fluid parameters were determined based on experimental measurements provided by the client and the availability of cooling water. The aim of the study is to obtain a comprehensive understanding of the cooler operation for the proposed geometry derived from balance calculations and client requirements. The CFD modeling includes the analysis of different cooling water inlet configurations and the influence of obstacles (swirl generators) placed in the annular cooling-water region to intensify heat transfer during cooling of the sampled medium. Due to the low velocity of the cooling medium, special attention was paid to the modification of the laminar boundary layer in the heat-transfer area. Since the process-air boundary conditions were kept fixed across all investigated variants, the evaluation and mutual comparison of the design variants is based primarily on the resulting temperature and velocity fields of the cooling medium rather than on a quantitative summary of the transferred heat duty or the resulting air outlet temperature.