Question

Poached eggs are cooked in bath of boiling water at 100°C. Over time they reach thermal equilibrium with the bath. They are then quickly removed from the boiling water and placed in ice water at 0°C to stop the cooking process. Assume the eggs are perfect spheres with a diameter of 4 cm, a thermal conductivity of 2 W/mK, and a thermal diffusivity of 1e-6 m2/s. It is very important that the temperature within the eggs remains spatially uniform during the cooling process.

A. Find the maximum heat transfer coefficient of the ice bath that is allowable. Assuming the heat transfer coefficient found in (a) is used.
B. Find the time the eggs should remain in the ice bath to cool them to 75°C.
C. How long does it take for the eggs to lose half of their thermal energy with respect to the bath
D. What is the heat transfer rate to the bath when the eggs are exactly 90°C.
E. Plot the transient temperature and heat transfer rate into the eggs for the entire process.

Answer 1

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Step-by-step explanation:

Kindly check the attached images below to see the step by step explanation to the question above and also note that I derived the whole expressions in variable firm that are required to solve this question and giving reasons for each step so that you can employ these steps in solving new problems.