Thermodynamic assessment of a solar water heater and treatment: an energy-exergy and sustainability analysis

This paper presents a thermodynamic and sustainability analysis for an experimentally developed solar water heater-with water treatment. The parabolic trough collector (PTC) is employed to capture thermal energy from the sun, which is subsequently utilized to increase the temperature of water. "Experimental and numerical" investigations are divided into two cases. Case 1: PTC with a glass cover and case 2: PTC without glass cover. Using an experimental analysis, data are collected, such as solar insolation and water outlet temperature. The collected data are utilized to analyse the thermodynamic performance of the proposed system. The first law of thermodynamics helps to quantify the system's performance, called energy analysis, whereas the second law of thermodynamics provides qualitative performance, called exergy analysis. The maximum energy and exergy efficiency achieved by the proposed system are 69.5% and 6.15%, respectively. Simultaneously, an exergy-based sustainability analysis is proposed, which shows how effectively the fuel exergy is utilized with the proposed system. The maximum sustainability index for case 1 is 1.07, and for case 2, it is 1.08. At the end of the experimental investigation, a slight decrease in total dissolved solid (TDS) was detected, indicating that if we enhance the performance of the PTC system, by changing the reflector material and installing evacuated tubes, the quality of the water may improve.