In this study, a 2000 mm long triple tube heat exchanger was designed and manufactured in this work with three intermediate tubes having annulus space of 26, 32, and 36 mm, respectively. Experimental investigations were carried out in the system to assess the percentage of energy savings. On the Diesel engine experiments were conducted by varying the load conditions at 25%, 50%, 75%, and 100%, respectively. Motor speed was varied at 900, 1200, and 1500 rpm, respectively, for each load condition. Also incorporated during the study were counter current, co-current with counter current, counter current with co-current, and co-current fluid flow patterns. It is found that, while increasing the load and speed, the heat transfer rate of the heat exchanger increased. It is also observed that, the fluid counter current flow pattern gave better performance compared to other flow pattern types. The effects of the operating parameters on the heat ex-changer's performance are represented by the Nusselt number and effectiveness. The results of the experiments were also compared with the thermal energy storage performance of the double tube heat exchanger. It is found that, compared to double tube heat exchanger, 20% of fuel energy was saved by using triple tube heat exchanger as waste heat recovery system.