Abstract
Spiral wound plastic heat exchangers represent an important class of heat exchangers, with high chemical resistance, low dimensions and reasonable costs. However, their design and optimisation are mainly based on practical experience, whereas comprehensive investigations have not been accomplished yet.
In this paper, we present the results of the collaborative research performed in the context of the EU-project INTHEAT (Intensified Heat Transfer Technologies for Enhanced Heat Recovery). The focus of this work is to gain a deeper understanding of the fundamental transport phenomena occurring in spiral wound plastic heat exchangers, thus allowing their performance to be improved. The apparatus chosen for the investigation was developed by Makatec GmbH (Makatec). It consists of spiral wound plastic films kept separated by spacer filaments building grid-like arrangements. In addition to the separation function, these arrangements must ensure an efficient mixing and thus an intensified heat transfer in the exchanger, whereas the mixing process strongly depends on the specific filament grid structure.
A Computational Fluid Dynamics (CFD) based model is developed that yields a detailed description of the flow and temperature fields in the complex geometric structure of the investigated spiral wound plastic heat exchanger. The simulations are performed for a single-phase liquid flow and for volumetric flow rates used in the Makatec test rig, with the help of the commercial software STAR-CCM+ (CD- adapco).The model is validated against experimental pressure drop data obtained at Makatec. The spacer geometry has then been varied and its influence on the flow behaviour evaluated. Enhanced turbulence is supposed to have a positive impact on the efficiency of the exchanger. Based on the obtained results, new spacer geometries are suggested in order to facilitate the turbulence and thus to achieve a better exchanger performance.
