Air-side heat transfer characteristics under wet conditions at lower ambient pressure of fin-and-tube heat exchanger

Abstract

Air-side heat transfer performance of plain fin-and-tube heat exchanger under fully wet conditions was experimentally investigated at different ambient air pressure. Test results were compared with three available correlations to examine their applicability in lower pressure. Tested samples had different row numbers of 2–4 and the experimental ambient pressure had a range of 40–100 kPa. The experimental data at atmospheric pressure is basically consistent with the correlations. Air-side jh factors increased by 16.51–40.19% as Re number decreased from 4000 to 1000, and balloon to 112.04–141.37% when Re number declined from 1000 to 200. The row number effect still exists at lower ambient pressure and only become more apparent. Available correlations fails to describe experiment data at lower ambient pressure, maximum average error soar from 15.90% to 137.41% when ambient pressure drop from 100 kPa to 40 kPa. By adding the environmental pressure correction factor to the Re number in correlation, the refined correlation can describe 90.43% of experimental data within ±20%, and have a mean deviation of 1.46%.