Calculate the rate of heat transfer from bottom to top of the slice in W/m2
A 5-cm thick slice of bread (k = 0.23 W/m°C) is placed on top of a hot plate at a temperature of 85oC. The top surface of the bread slice is maintained at 25°C.a.Calculate the rate of heat transfer from bottom to top of the slice in W/m2
Thermal Conductivity
The thermal conductivity of a substance is the measure of the ability of the substance to conduct heat. It can be defined as the rate at which heat is transferred through a unit cross-section of a material when a temperature gradient exists perpendicular to the heat flow. It is denoted by and its SI unit is .
The amount of heat flowing through a slab of the cross-sectional area and of thickness in time from the side at a higher temperature to the side of lower temperature is given by
Therefore the amount of heat supplied per unit area per unit time is given by
In the question given is the thickness of the slice of bread
the temperature of the bottom surface of the slice
the temperature of the top surface of the slice
Thermal conductivity of the slice
Therefore the rate of heat transfer from the bottom to the top of the slice per unit area is
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