Waste heat recovery using evacuated U-tube solar water heater-thermoelectric generator hybrid system and fishtail vortex generators

This study investigates the performance of an innovative hybrid system comprising an Evacuated U-tube Solar Water Heater (EUSWH) integrated with a Thermoelectric Generator (TEG). To enhance thermal and electrical performance, fishtail vortex generators (FVGs) are strategically implemented on the hot side of the TEG module. The study examines the influence of key operating parameters, including incident solar radiation intensity, water mass flow rate, inlet EUSWH temperature, and the incorporation of vortex generators, on various EUSWH, TEG, and the overall hybrid system performance metrics. The analysis reveals that the EUSWH achieves peak performance at the maximum solar irradiance (G). However, increasing the mass flow rate reduces the outlet water temperature ( T out,EUSWH ), while enhancing the thermal energy output ( Q EUSWH ) and thermal efficiency ( η EUSWH ). Conversely, the inlet EUSWH temperature ( T in,EUSWH ) increases T out,EUSWH, but decreases Q EUSWH and η EUSWH . The highest TEG efficiency, recorded at 2.66%, occurs under conditions of (G = 1000 W/m 2 ), mass flow rate = 0.1kg/s, and T in,EUSWH = 303K, with the FVG-enhanced channel. The hybrid system efficiency ( η HS ) exhibits a maximum value of 0.023% at G =1000W/m 2 , mass flow rate=0.1 kg/s, and T in,EUSWH =303K. The hybrid system delivers heated water and electrical power concurrently, incorporating vortex generators that significantly augment its overall performance.