Thermal Conductivity Examples

Thermal Conductivity Examples

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Solved Examples

Question 1: Calculate the thermal conductivity through a conductor when 30 kW of heat flows through it having length of 4 m and area of 12 m2

if the temperature gradient is 40 K.
Solution:

Given :
Heat flow Q = 30 kW, length L = 4 m, Area A = 12 m2

, temperature difference Δ T = 40 K.

The thermal conductivity is given by,
k = QLAΔT
= 30×103W×4 m12 m2×40 K

= 250 W/m K.

Question 2: What is the temperature gradient if a conductor at 70 K after a flow of heat of 20 kW reaches a temperature of 100 K?
Solution:

Given :
Heat flow Q = 20 kW, length L = 4 m, initial temperature Ti

= 70 K, Final temperature Tf = 100 K, temperature gradient Δ T = ?

The temperature gradient is given by
Δ T = Ti - Tf
= 100 K - 70 K
= 30 K.