The term "heat transfer augmentation techniques" refers to several strategies used to boost the pace of heat transfer without significantly impacting the system's overall performance. Heat exchangers use these methods. These methods can either be active or passive. In contrast to passive approaches, which do not require any more energy to boost the thermohydraulic performance of the system, active methods require external power to enter the process. When examining friction losses and heat transfer enhancement, passive approaches are frequently utilised in experimental and numerical applications to conserve energy. Various elements found in the fluid flow route, such as twisted tapes, coiled or tangled wires, and nozzle turbulators, are only a few of thenumerous passive approaches for accelerating heat transfer rate. The fluid to fluid heat exchange is considered in current research. The majority of heat transfer coefficient studies are conducted under constant wall temperatures or constant heat flow. For the parallel flow and counter flow configurations of the helical coil and straight tube heat exchangers, the effectiveness, overall heat transfer coefficient, effect of cold-water flow rate on heat exchanger effectiveness when hot water mass flow rate is kept constant, and effect of hot water flow rate on effectiveness when the cold-water flow rate is kept constant, were studied and compared. The Wilson plot method was used to calculate the interior heat transfer coefficient. Then, using the interior heat transfer coefficient as a foundation, Nusselt no and correlation were derived. All measurements were made when the heat exchanger was operating at a steady state.