Enhancement and optimization of thermo-hydraulic characteristics of a heat exchanger with three fluids used in sustainable heating applications

Experimental investigation of the thermo-hydraulic and exergetic performance of a heat exchanger with three fluids (HEFT) was carried out in the present work. The HEFT comprises of two straight tubes and a helical tube inserted in between the outermost and the innermost tube for better heat transfer. The present heat exchanger is projected for heating of two fluids (TF2: normal water and TF3: air) simultaneously by another fluid TF1 (hot water). During the examination, three levels of TF1 flow rate (i.e., 100, 200, and 300 LPH), three levels of TF2 flow rate (i.e.,50, 100, and 150 LPH), three levels of TF3 flow velocity (i.e., 1, 2, and 3 m/s, and two levels of TF1inlet temperature (i.e., 60, and 80 degrees Celsius) are maintained. A coupled Taguchi-Grey relational analysis is employed to determine the optimum combination of control parameters to forecast optimized overall performances. The outcomes show that, the inlet temperature of TF1 is forecasted as the most decisive factor for the JF factor, exergy efficiency, and sustainability index with a contribution of 41.29%, 63.06%, and 60.66% respectively. The optimized performance of the HEFT is forecasted at 60℃ inlet temperature of TF1, 100 LPH flow rate of TF1, 150 LPH flow rate of TF2, and 3 m/s velocity of TF3 and confirmed with significant enhancement in Grey relational grade of 32.9%.