Estimate the time when the temperature at the geometric center of a 6 cm Example 4.26

diameter apple held in a 2°C water stream reaches 3°C. The initial uniform

temperature of the apple is 15°C. The convective heat transfer coeffi cient in

water surrounding the apple is 50 W/(m 2

°C). The properties of the apple are

thermal conductivity k 0.355 W/(m °C); specifi c heat cp 3.6 kJ/(kg °C); and

density ρ 820 kg/m 3

.

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