Chapter 11, Problem 11.6P

A novel design for a condenser consists of a tube of thermal conductivity $200\text{ W/m}\cdot \text{K}$ with longitudinal finssnugly fitted into a larger tube. Condensing refrigerantat $45°C$ flows axially through the inner tube, while waterat a flow rate of $0.012\text{ kg/s}$ passes through the six channels around the inner tube. The pertinent diameters are $D_1=10$ mm, $D_2=14$ mm, and $D_3=50$ , while thefin thickness is $t=2$ mm. Assume that the convection coefficient associated with the condensing refrigerant isextremely large.

Determine the heat removal rate per unit tube length ina section of the tube for which the water is at $15°C$ .