Tube Wall Temperature, t_w: It should be noted that film coefficients are calculated at bulk temperatures whereas heat transfer occurs at the wall. A viscosity correction factor is employed to find the correct heat transfer coefficient. Tube wall temperature relationships depend upon whether cold or hot fluid is flowing in the pipe. See Table 5.6.

Example 5.7: Bulk temperatures of cold and hot fluids are 100 °F, and 130 °F, respectively. Find the tube wall temperature if cold fluid is flowing in the inside pipe. Use the following data:

Solution:

$ Tube wall temperature, t_w when cold fluid is flowing inside pipe

Tube wall temperature for cold fluid flowing inside pipe is 112 °F.