Simple 1D thermal conductivity calculations.xls



KNOWN: One-dimensional system with prescribed thermal conductivity and thickness.

FIND: Unknowns for various temperature conditions and sketch distribution.

ASSUMPTIONS: 1) Steady-state conditions.

2) One-dimensional conduction.

3) No internal heat generation.

4) Constant properties.

ANALYSIS: Using the Rate equation and temperature gradient, the unknown quantities for each case can be found.

Calculation Reference
Fundamentals of Heat and Mass Transfer - Frank P. Incropera

To perform simple 1D thermal conductivity calculations for a one-dimensional system with a prescribed thermal conductivity and thickness, you can follow these steps:

  1. Determine the temperature conditions: Identify the known temperatures at specific points in the system and the unknown temperatures that need to be calculated.

  2. Define the temperature gradient: The temperature gradient (?T/?x) represents the change in temperature with respect to the distance in the system. It can be expressed as the difference in temperature between two points (ΔT) divided by the distance between those points (?x).

  3. Apply the rate equation: The rate equation for conduction heat transfer states that the heat flux (q) is equal to the product of the thermal conductivity (k), the cross-sectional area (A), and the temperature gradient (?T/?x):

    q = -k * A * (?T/?x)

    The negative sign indicates that heat is transferred in the direction of decreasing temperature.

  4. Calculate the unknown quantities: Using the rate equation, you can determine the unknown temperatures by rearranging the equation based on the given conditions and solving for the unknown variables.

  5. Sketch the temperature distribution: Once the unknown temperatures are determined, you can sketch the temperature distribution along the system by plotting temperature as a function of position or distance.

By following these steps, you can perform simple 1D thermal conductivity calculations for a one-dimensional system with a prescribed thermal conductivity and thickness. The assumptions of steady-state conditions, one-dimensional conduction, no internal heat generation, and constant properties allow for simplified analysis.

24 Jan 2007
Last Modified
19 Jul 2023
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