Oranges of 2.5-in-diameter (k = 0.26 Btu/hftF and = 1.4 3 10 -6 ft 2 /s)

Oranges of 2.5-in-diameter (k = 0.26 Btu/h·ft·°F and α = 1.4 3 10^-6 ft²/s) initially at a uniform temperature of 78°F are to be cooled by refrigerated air at 25°F flowing at a velocity of 1 ft/s. The average heat transfer coefficient between the oranges and the air is experimentally determined to be 4.6 Btu/h·ft²·°F. Determine how long it will take for the center temperature of the oranges to drop to 40°F. Also, determine if any part of the oranges will freeze during this process.