Computational modelling of plate-fin and tube heat exchanger for heat transfer and pressure drop analysis

 

Introduction

The plate-fin and tube heat exchanger are a cross-flow type heat exchanger, which uses plates as fins as indicated in (Figure 1); therefore, the flow external to the tubes is unmixed. Often, it is categorized as a compact heat exchanger to emphasize its relatively high heat transfer surface area to volume ratio. The plate fin and tube heat exchanger is widely used in many industries, including the aerospace industry, for its compactness and low weight. Different types of fin patterns, in addition to the plate, exist, such as louver, convex-louver, and wavy; however, in general, the plate fin tends to be the best in terms of performance and of constructional effectiveness. The tube geometry used in plate fin and tube heat exchangers is either circular or elliptical. The majority of the studies dealing with plate fin and tube heat exchangers have been conducted resorting to experiments.
Shepherd [1] analyzed early experimental data for heat transfer of plate fin and circular tube heat exchanger. Later on, Schulemberg [2] extended the analysis to plate fin and elliptical tubes. Kayansayan [3] investigated experimentally the effects of the outer surface geometry on the performance of flat plain fin and circular tube heat exchangers with four-row coils. Jang et al. [4] studied fluid flow and heat transfer over a multi row (1–6 rows) plate-fin and tube heat exchanger both numerically and experimentally. They considered effects of different geometrical parameters such as tube arrangement, tube row numbers and fin pitch (8–12 fins per inch) for the Reynolds number (based on the fin spacing and the frontal velocity) ranging from 60 to 900 and observed an average heat transfer coefficient of staggered arrangement is 15%–27% higher than that of in-lined arrangement, while the pressure drop of staggered configuration is 20%–25% higher than that of in-lined configuration. Wang et al. [5] investigated experimentally heat transfer and pressure drop for plate fin and tube heat exchanger. Beecher et al. [6] reported heat transfer data for twenty wavy geometries. Kays et al. [7] analyzed heat transfer and pressure drop of heat exchanger with louvered fins. Achaichia et al. [8] experimentally studied the heat transfer and pressure drop of tube and louvered fin surfaces; later on the same authors [9] conducted a numerical study for flow in the laminar regime. Webb et al. [10] performed a flow visualization study of the louvered fin geometry with a flat tube. Sahnoun et al. [11] developed an analytical model for predicting air-side heat exchanger performance of louvered fin geometry. Rocha et al. [12] experimentally estimated the overall heat transfer coefficient of plate fin heat exchangers by considering circular and elliptical tubes. Kundu et al. [13] conducted a dimensional optimization for plate fin and tube heat exchangers with equilateral staggered triangular and rectangular pitch. Romero-Mendez et al. [14] used numerical techniques to estimate the effect of spacing between fins on heat transfer and pressure drop for single row fin and tube heat exchanger. Wang et al. [15] experimentally analyzed the effect of tube rows, fin pitch, and tube diameter on heat transfer and pressure drop for plate fin and tube heat exchanger. Wang et al. [16] presented correlations of the Colburn and friction factors for plate fin and tube heat exchangers. Saboya et al. [17] determined the average heat transfer coefficient for plate fin and elliptic tube heat exchangers using the naphthalene sublimation technique. Torikoshi et al. [18] numerically investigated a plain fin and tube heat exchanger. Erek et al. [19] numerically investigated the effect of fin geometry on heat transfer and pressure drop for plate fin and tube heat exchangers, but they used one particular mass flow rate of the flue gas. Abu Madi et al. [20] determined the effect of geometrical parameters of flat and corrugated fins and the results are presented in terms of Colburn and friction factors.
The present work is focused on the numerical investigation estimation of heat flow, pressure drop, and temperature and velocity fields for the plate fin and tube heat exchanger with one row tube configuration; the analysis will be focused on the effect of fin spacing, ellipticity and fin height on the numerically predicted parameters.

 

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