Shell and tube heat exchangers (STHX) are still a popular choice in many industrial applications because of their substantial heat transfer area to volume and weight ratios and ability to meet nearly any service need. They're commonly found in nuclear power plants, steam generators, and feedwater heaters. Because of their excellent effectiveness, STHXs are being used in a growing number of industrial procedures. The aim of the present investigation is to theoretically calculate the performance parameters of the STHX at different conditions. According to the theoretical study, the heat exchanger's effectiveness declines as the hot fluid's inlet temperature rises. At a constant value of Reynolds number for the hot fluid, the effectiveness is maximum for Reynolds number of 1000 for the cold fluid. As the inlet temperature of the hot fluid rises, the heat exchanger's performance rises as well. It was also discovered that as the inlet temperature of the hot fluid increases, the tube side pressure drop increases at a constant value of the Reynolds number of hot fluid.