One way of measuring the thermal conductivity of a material is to sandwich an electric thermofoil heater between two identical rectangular samples of the material and to heavily insulate the four outer edges, as shown in the figure. Thermocouples attached to the inner and outer surfaces of the samples record the temperatures. During an experiment, two 0.5-cm thick samples 10 cm 3

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.4P: 1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus...

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Concept explainers

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.

Question

One way of measuring the thermal conductivity of a
material is to sandwich an electric thermofoil heater between
two identical rectangular samples of the material and to heavily
insulate the four outer edges, as shown in the figure. Thermocouples
attached to the inner and outer surfaces of the
samples record the temperatures.
During an experiment, two 0.5-cm thick samples 10 cm 3
10 cm in size are used. When steady operation is reached, the
heater is observed to draw 25 W of electric power, and the temperature
of each sample is observed to drop from 82°C at the inner surface to 74°C at the outer surface. Determine the thermal
conductivity of the material at the average temperature.

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