Frozen grapes are a delicious snack, and are particularly refreshing in the summertime. Using your advanced...

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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: 75°F (about 24°C), and can be considered to be spheres with a diameter of 1.75cm. They have a density of 840 kg/m³, a specific heat of 4.81 kJ/kg, and a thermal conductivity of 0.418 W/m °C Your freezer is at -15°C, and has a heat transfer coefficient of 24 W/m² °C. 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: 75°F (about 24°C), and can be considered to be spheres with a diameter of 1.75cm. They have a density of 840 kg/m³, a specific heat of 4.81 kJ/kg, and a thermal conductivity of 0.418 W/m °C Your freezer is at -15°C, and has a heat transfer coefficient of 24 W/m² °C.