Assessment of the performance of solar water heater: an experimental and theoretical investigation

Abstract

This study aims to evaluate the performance of a flat plate solar water heater (SWH) theoretically and experimentally. The thermal performance of the SWH was predicted using Fortran 90 programming language. SWH was designed as a square shape with dimensions of 110 cm length, 120 cm width and 10 cm depth and tested by integrating with a modified solar distiller to increase the water temperature in the basin at a constant mass flow rate of 1.2 l/min. The tests were conducted under the weather condition of Yekaterinburg city, Russia, from June to September of 2019, and a typical day was chosen for each month (19 June, 17 July, 22 August and 15 September). The study revealed that the highest efficiency of the solar water collector obtained at the highest value of the intensity of solar radiation at mid-day. The maximum thermal efficiencies achieved on 17 July of 2019 were ~67% and 66% based on theoretical and experimental analyses, respectively. A simultaneous increase in the water temperature and the intensity of solar radiation has been observed. During the four typical days of the experiment, the highest water temperatures of the solar collector were recorded during midday, i.e. $57.2{}^{\circ}\mathrm{C},64.4{}^{\circ}\mathrm{C},52.4{}^{\circ}\mathrm{C}\kern0.5em \mathrm{and}\ 49{}^{\circ}\mathrm{C}$ at the inlet, and $62.8{}^{\circ}\mathrm{C},71{}^{\circ}\mathrm{C},57.4{}^{\circ}\mathrm{C}$ and $53.2{}^{\circ}\mathrm{C}$ at the outlet for 19 June, 17 July, 22 August and 15 September 2019, respectively, while the solar radiation intensities recorded are $957,1022,840\kern0.5em \mathrm{and}\ 723\ \mathrm{W}/{\mathrm{m}}^2$ for the test days.