Chapter 1, Problem 1.80P

Consider the steam pipe of Example 1.2. The facilitiesmanager wants you to recommend methods for reducing the heat loss to the room, and two options are proposed. The first option would restrict air movementaround the outer surface of the pipe and thereby reducethe convection coefficient by a factor of two. The second option would coat the outer surface of the pipe witha low emissivity $\left(\in =0.4\right)$ paint.
(a) Which of the foregoing options would you recommend?
(b) To prepare for a presentation of your recommendation to management, generate a graph of the heatloss $q^{\prime }$ as a function of the convection coefficient for $2\le h\le 20{\text{W/m}}^{\text{2}}\cdot \text{K}$ and emissivities of 0.2, 0.4, and 0.8. Comment on the relative efficacy ofreducing heat losses associated with convection andradiation.