Heat exchanger is a device that is used to transfer thermal energy between two or more fluids. To design and analysis a shell and tube heat exchanger with continuous helical baffles to improve the shell side performance of shell and tube heat exchanger Considering same flow area for both new helical design and the existing design (i.e.) conventional segmental baffle to compare the both result. However, the traditional shell and tube heat exchangers with segmental baffles has many disadvantages such as low heat transfer coefficient due to the segmental baffle arrangement, large back mixing, fouling, high leakage flow, and large cross-flow. Especially, segmental baffles bring on significant pressure drop across the exchanger when changing the direction of flow. With the help of research facilities and industries have shown much better performance of helical baffle heat exchangers as compared to the conventional ones. This results in relatively high value of shell side heat transfercoefficient, low pressure drop, and low shell side fouling, reduced bypass effects, and prevention from flow-induced vibration.