Mechanical seals in centrifugal pumps play an important role in various industrial equipment. Heat generation occurs due to friction between the stationary and rotating rings at the seal interface. In this study, a numerical model is used to analyze the heat generation at the interface, heat conduction to the rings, and heat convection to the surrounding fluid in the seal chamber. The numerical model is verified using results from the literature. Furthermore, a new design for the stationary ring is proposed to improve the thermal efficiency of the seal. The redesigned mechanical seal reduces the interface temperature, enhancing thermal efficiency. The redesigned stationary ring is then compared with the original configuration at different rotational speeds of the rotating ring and different spring pressures. The redesigned stationary ring has better thermal efficiency than the conventional design by 16%. Due to higher thermal efficiency, the improved design has a lower surface temperature of 10.5 °C than the existing design. The proposed design will reduce seal failure by enhancing its thermal performance and operational life.