Comparison of one-dimensional and two-dimensional models for wet-surface fin efficiency of a plate-fin-tube heat exchanger

This paper investigates the wet-surface fin efficiency of a plate-fin-tube heat exchanger. Depending on the compromise made between accuracy and complexity, a one-dimensional analytical model, a one-dimensional numerical model and a two-dimensional numerical model are proposed respectively for fin efficiency together with the corresponding computation algorithms. The one-dimensional numerical model considers the local mass transfer effect. The two-dimensional model takes into account of the complex fin geometry and the variation of moist air properties over the fin. In the analytical model, two parameters M∗ and T∗a are employed in the solution in place of the C parameter that is commonly used in the literature. A quantitative comparison of these models together with a widely used method by McQuiston is presented. Meanwhile, the fin performance of a plate-fin-tube heat exchanger is investigated under a variety of fin geometric parameters and airflow conditions, especially for a wide range of air relative humidity (from 20 to 95%). Due to the different simplifications made in each model, the differences among the calculation results are found to be significant. Finally, the applications and limitations of these models are discussed along with the error analysis.