A heat exchanger is a device which is designed to exchange heat efficiently from one medium to another. The basic component of a heat exchanger can be viewed as a type which consists of one fluid running through it and another fluid flowing by on the outside. There are three heat transfer operations that need to be described: • Convective heat transfer from fluid to the inner wall of the tube. • Conductive heat transfer through the tube wall. • Convective heat transfer from the outer tube wall to outside fluid. Heat exchanger are classified according to type of construction and flow arrangement. They are I. Concentric tube type II. Shell and tube type III. Cross flow type Tube banks are widely employed in cross flow heat exchangers, which are used in numerous services and industrial applications. Transfer of heat inflow across a bank of tubes is of a particular importance in design of heat exchangers. Analytical studies were performed to investigate the transfer of heat in cross flow tube banks under isothermal boundary condition.