Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, part II: Correlation

An investigation of the thermo-hydraulic performance of the smooth wavy fin-and-elliptical tube heat exchangers utilizing new type vortex generators

This study presents an empirical correlation describing the airside performance of herringbone wavy fin pattern. A total of 61 samples containing approximately 570 data points are used in the regression analysis. The proposed heat transfer correlation can describe 91% of the test data within ±15% with a mean deviation of 6.98% while the proposed friction correlation can describe 85% of the database within ±15% with a mean deviation of 8.82%.

Empirical correlations for heat transfer and flow friction characteristics of herringbone wavy fin-and-tube heat exchangers

The airside performance of fin-and-tube heat exchangers having slit geometry is experimentally investigated in this study. A total of 12 samples were tested and compared. Effects of fin pitch and the number of tube row were examined. The test results indicated that the heat transfer performance increase with decrease of fin pitch for N=1. However, for N⩾4, the effect of fin pitch on the heat transfer performance is reversed. In addition to the effect of fin pitch, the heat transfer performance decrease with increase of the number of tube row and the friction factors are relatively independent of the number of tube row. Based on the present test results and those from previous investigations, a general correlation is proposed to describe the airside performance of the slit fin configuration, the mean deviations of the proposed heat transfer and friction correlation are 5.5 and 3.8%, respectively.

An investigation of the airside performance of the slit fin-and-tube heat exchangers.

A heat transfer and friction correlation for wavy fin-and-tube heat exchangers

An experimental study was carried out to examine the effects of the waffle height, including three different values of waffle height-1.18, 1.32, and 1.58 mm-on the heat transfer and friction characteristics of typical fin-and-tube heat exchangers having wavy fins. A total of 13 samples of heat exchangers, nine of them having wavy fins and the other four having plain fin configurations, were tested. The test results indicated that the effect of waffle height on the heat transfer enhancement ratio, compared to the plain-fin counterpart, is pronounced only for smaller fin pitch and larger waffle height, while its effect on the pressure drop is considerably significant throughout the test range.

Nien Fong Chiou

Papers

Effects of Waffle Height on the Air-Side Performance of Wavy Fin-and-Tube Heat Exchangers