A stainless steel tube (k= 14 w/m*k) used to transport a chilled pharmaceutical, has an inner diameter of 36 mm and a wall thickness of 2 mm. The pharmaceutical and ambient air are at temperatures of 6 C and 23 C, respectively, while the corresponding inner and outer convention coefficients are 400 W/m^2K and 6 W/m^2 K respectively.
A). What is the heat transfer rate per unit of tube length?
B). What is the heat transfer rate per unit length if a 10 mm thich layer of calcium silicate insulation (k= 0.05 w/m*k) is applied to the outer surfac of the tube?