Heat transfer and pressure drop play significant roles in the production of entropy rate. This study examines an analytical approach of using heat transfer and pressure drop power curve correlations from experimental data to determine and characterize the irreversible distribution ratio and pumping power of a smooth tube heat exchanger operating in the laminar, transitional, and turbulent flow regimes. The ratio expresses the influence of entropy generated by friction to that of heat transfer. The heat exchanger operated using water as the working fluid over a Reynolds number range of 1330 to 10449 and an applied heat flux of 2 kW/m². Characterizing the entropy generation rate due to friction is crucial as this is inextricably linked to determining the pumping power. The pumping power was investigated to establish the relationship with Reynolds numbers in the different flow regimes. The results showed that the irreversibility distribution ratio and pumping power increased with increasing Reynolds number in all flow regimes. When plotted on a log-log scale, the irreversibility distribution ratio and pumping power increase were characterized with varying gradients in the different flow regimes, making it possible to identify each flow regime. In the laminar flow regime, the irreversibility distribution ratio and pumping power were lower compared with that of the transitional flow regime. In the turbulent flow regime, the irreversibility distribution ratio and power were higher than that of the transitional flow regime. As the pumping power is directly related to energy consumption, it was concluded that operating heat exchangers in the transitional flow regime provides a reduced energy consumption as compared with the turbulent flow regime.