Heat Transfer
Heat transfer lectures by Professor Josua Meyer (2014). Topics covered in the lectures include: transient or unsteady heat conduction, convection heat transfer, external and internal forced convection, heat exchangers, thermal radiation including atmospheric and solar radiation. The lectures are based on the textbooks of White (8th ed) and Cengel and Ghajar (4th ed) and were presented as part of a heat transfer class to the fourth year students of the Department of Mechanical and Aeronautical Engineering, University of Pretoria.
| Lecture 07 - Transient Heat Conduction: Plane Walls, Cylinders and Spheres |
This lecture continues with unsteady/transient heat conduction, specifically in large plane walls, long cylinders and spheres. After the exact equation for one dimensional heat transfer was derived in previous lecture an example is done. The example is about a dead body with temperatures known and the problem is to found the time of death. Two approaches are used. The first approach using a lumped system approach which should not give good results as the Biot number is too large. The second approach is to use a one term approximation. The one term approximation was first done incorrectly to illustrate that the Biot number calculation for the lumped system approach cannot be used. Thereafter it was done correctly using the correctly calculated Biot number.
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