Experimental and ANN-based analysis of thermo-hydraulic-exergetic performance in a three-fluid heat exchanger with two thermal communication systems

The performance of a heat exchanger with three fluids (HETF) in a suburban heating system for simultaneous water and space heating is assessed by varying flow rates, inlet temperature, and flow configurations. The investigated HETF, an adaptation of the twin-tube heat exchanger, operates with hot water (TF1), cold water (TF2), and air (TF3). This study analyzes the thermal-hydraulic and exergetic performance of the HETF under varying operating conditions: TF1 flow rates ranging from 100 to 300 LPH, TF2 from 50 to 150 LPH, TF3 from 14,650 to 43,950 LPH, and TF1 inlet temperatures between 60°C and 80°C, for two distinct flow configurations. The overall heat transfer coefficient (U), exergy efficiency (ɛ), pressure drop (∆p), and JF factor are employed as key performance metrics. The results show that the highest overall heat transfer coefficient (U) for TF2 fluid (290 W/m 2 K) occurs at TF1, TF2, and TF3 flow rates of 200, 150, and 29,300 LPH, respectively. For TF3 fluid, the peak U (28.55 W/m 2 K) is observed at 200, 100, and 43,950 LPH, respectively. Maximum exergy efficiency (79.3%) is achieved at 200, 50, and 29,300 LPH with a TF1 inlet temperature of 60°C. The highest JF factor (0.247) is recorded at a TF1 flow rate of 100 LPH and 60°C inlet temperature. To enhance the reliability of predictions, an artificial neural network (ANN)-based model was developed, showing a predictive accuracy of 99.93%, which significantly exceeds the 85% accuracy achieved by traditional modeling approaches.