Talaghat - Department of oil, gas and chemical engineering Shiraz university – Shiraz ,Iran
Taheri - Department of oil, gas and chemical engineering Shiraz university – Shiraz ,Iran

In this paper, the laminar tube flow is considered for tube with constant wall temperature. By a shell thermal energy balance ,we derive a second- order differential equation that describes the temperature profile in tube .To do this , an approach similar to that used in thermal boundary layer is followed by polynomial with four arbitrary constants. After the determination of the temperature profile by applying boundary conditions, bulk temperature and heat transfer coefficient is calculated and an expression for the term of the Nusselt number is obtained and compared with other refrences.

Heat transfer coefficient , tube , laminar flow , constant wall temperature , polynomial , Nusselt No