Numerical investigation of flow and heat transfer performance of solar water heater with elliptical collector tube

The flow and heat transfer performance of solar water heaters for different initial temperatures (273K, 283K, 293K, 303K and 313K) with elliptical collector tubes are evaluated using numerical simulation. The predicted results match fairly well with experimental data. Results indicate that, the temperature distributions of all the tube cross sections are alike, but the velocity profiles of them are much dissimilar. The fluid velocity near the wall decrease with decrease in the ratio of the cross section major and minor axis, which induces the reduction in the circulation rate through the collector tubes, which is not conducive to heat transfer. The mean Nusselt number of solar water heater with b/a=1 (b and a here are respectively major and minor axis of collector tube cross section) are respectively 59% and 19% larger than the solar water heaters withb/a=0.6 and 0.8 for the temperature ranging from 273K to 313K. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).