ENHANCEMENT AND OPTIMIZATION OF THERMOHYDRAULIC CHARACTERISTICS OF A HEAT EXCHANGER WITH THREE FLUIDS USED IN SUSTAINABLE HEATING APPLICATIONS

Abstract

An experimental investigation of the thermohydraulic and energetic performance of a heat exchanger with three fluids (HETF) was carried out in the present work. The HETF comprises 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 the heating of two fluids (TF2: normal water and TF3: air) simultaneously by another fluid TF1 (hot water). The present investigation is carried out with 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 TF1 inlet temperature (i.e., 60°С and 80°С). A coupled Taguchi-Grey relational analysis is employed to determine the optimum combination of control parameters to predict optimized overall performances of the HETF. The outcomes show that the TF1 inlet temperature has significant influence on 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 HETF is predicted at 60°С TF1 inlet temperature, 100 LPH TF1 flow rate, 150 LPH TF2 flow rate, and 3 m/s TF3 velocity and the same result got confirmed with significant enhancement in Grey relational grade of 32.9%.