Frozen grapes are a delicious snack, and are particularly refreshing in the summertime. Using your advanced knowledge of transport phenomena, you have decided to determine exactly how long you will need to keep a grape in the freezer to ensure it is completely frozen (because you don't want to wait any longer than absolutely necessary to enjoy a tasty grape). Assume the following parameters: The grapes are initially at room temperature: 75F (about 24C), and can be considered to be spheres with a diameter of 1.75cm. They have a density of 840 kg/m, a specific heat of 4.81 kJ/kg, and a thermal conductivity of 0.418 W/m C Your freezer is at -15C, and has a heat transfer coefficient of 24 W/m C.