A spherical ball (15 cm in diameter) with a density of 1000 kg/m³, specific heat capacity of 4180 J/kg-K and thermal conductivity of 0.62 W/m-K is removed from an oven at a uniform temperature of 150 °C. The ball is then left to cool down in steady air at 10 °C. Calculate the heat transfer coefficient for this process and the time for the surface of the ball to drop to 20 °C. Use the following equation to solve this problem (characteristic dimension of the sphere is the diameter). 0.589 · Ra* Nu = 2+ 0.469 16 Pr

A spherical ball (15 cm in diameter) with a density of 1000 kg/m³, specific heat capacity of 4180 J/kg-K and thermal conductivity of 0.62 W/m-K is removed from an oven at a uniform temperature of 150 °C. The ball is then left to cool down in steady air at 10 °C. Calculate the heat transfer coefficient for this process and the time for the surface of the ball to drop to 20 °C. Use the following equation to solve this problem (characteristic dimension of the sphere is the diameter). 0.589 · Ra* Nu = 2+ 0.469 16 Pr

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Question

A spherical ball (15 cm in diameter) with a density of 1000 kg/m³, specific heat
capacity of 4180 J/kg-K and thermal conductivity of 0.62 W/m-K is removed
from an oven at a uniform temperature of 150 °C. The ball is then left to cool
down in steady air at 10 °C. Calculate the heat transfer coefficient for this process
and the time for the surface of the ball to drop to 20 °C. Use the following
equation to solve this problem (characteristic dimension of the sphere is the
diameter).
0.589 . Ra*
Nu = 2+
0.469 16
Pr

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