(a) Consider a frozen, 0.4-kg spherical piece of ground beef at an initial temperature of T; = -20°C placed in a microwave oven with T = 30°C and h = 15 W/m²K. Determine how long, in min, it will take the beef to reach a uniform temperature of T = 0°C, with all the water in the form of ice. Assume the properties of the beef are the same as ice, and assume 3% of the oven power (P = 1 kW total) is absorbed in the food. (b) After all the ice is converted to liquid, determine how long, in min, it will take to heat the beef to Tƒ if 95% of the oven power is absorbed in the food. Assume the properties of the beef are the same as liquid water. = 80°C

(a) Consider a frozen, 0.4-kg spherical piece of ground beef at an initial temperature of T; = -20°C placed in a microwave oven with T = 30°C and h = 15 W/m²K. Determine how long, in min, it will take the beef to reach a uniform temperature of T = 0°C, with all the water in the form of ice. Assume the properties of the beef are the same as ice, and assume 3% of the oven power (P = 1 kW total) is absorbed in the food. (b) After all the ice is converted to liquid, determine how long, in min, it will take to heat the beef to Tƒ if 95% of the oven power is absorbed in the food. Assume the properties of the beef are the same as liquid water. = 80°C

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.20P

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