In a chicken processing plant, whole chickens averaging 5 lbm each and initially at 65°F a...

In a chicken processing plant, whole chickens averaging 5 lbm each and initially at 65°F are to be cooled in the racks of a large refrigerator that is maintained at 5°F. The entire chicken is to be cooled below 45°F, but the temperature of the chicken is not to drop below 35°F at any point during refrigeration. The convection heat transfer coefficient and thus the rate of heat transfer from the chicken can be controlled by varying the speed of a circulating fan inside. Determine the heat transfer-coefficient that will enable us to meet both temperature constraints while keeping the refrigeration time to a minimum. The chicken can be treated as a homogeneous spherical object having the properties ρ = 74.9 lbm/ft3, cp = 0.98 Btu/lbm · °F,k = 0.26 Btu/h · ft · °F, and α = 0.0035 ft2/h.

I

FIGURE P18-52E