A CFD investigation was carried out to compare the thermal performance of the 1EHT-1 and 1EHT-2 tubes with a smooth surface tube using R410A at 311K as working fluid. These tubes have enhanced heat transfer area produced by a series of dimples/protrusions and petals distributed over its surface. All the stages of this simulation were conducted using Ansys Fluent. Initially, the physical model of the fluid domain was developed using the Design Modeler module. The tubes had an internal diameter of 8.32mm. They were subsequently imported to the meshing module for the griding process. To ensure high accuracy in the results, the mesh average orthogonal quality was kept above 0.7, with the minimum orthogonal quality higher than 0.1. For the numerical simulations, SST k-ω model was used, with Reynolds number ranging from 16000 to 35000. The results of the heat transfer coefficient were validated with previous experimental work. As expected, the heat transfer coefficient is higher for the 1EHT tubes. For instance, at Reynolds number of nearly 16000, the HTC for 1EHT-1 tube was 1097.5 W.K-1.m-2, followed by the 1EHT-2 with 1058 W.K-1.m-2 and nearly 846 W.K-1.m-2 for the smooth tube. When compared with the experimental results, a good agreement was observed, and the HTC relative error (RE) for all tubes tested was below 10%. It is possible to conclude that the CFD model used presents as a powerful tool to simulate and predict heat transfer with good accuracy, allowing optimization in heat exchangers design and operational parameters.

Cfd Study of the Thermal Performance Improvement of a Counter-Flow Heat Exchanger Using Enhanced Surface Tubes

Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2021/volume/84874

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