Thermal Analysis Of The Composite Wall Subjected To Time Dependent Temperature Variation

• Main Author: Wong, Nguk Sing
• Format: Monograph
• Language: English
• Published: Universiti Sains Malaysia 2004
• Subjects: T Technology; TJ Mechanical engineering and machinery
• Online Access: http://eprints.usm.my/57118/1/Thermal%20Analysis%20Of%20The%20Composite%20Wall%20Subjected%20To%20Time%20Dependent%20Temperature%20Variation_Wong%20Nguk%20Sing.pdf; http://eprints.usm.my/57118/

The analysis of thermal behaviour of composite wall subjected to unsteady-state heat conduction is becoming increasingly important in building designs today. Many researches have been carried out in this field in order to develop new methods that will lead to progressions and improvements. The main objective of this project is to develop a program that can be used to analyze thermal behaviour of composite walls. In order to simplify the computations, the problem is assumed to be one-dimensional (only in the direction normal to the surface of walls) unsteady-state heat conduction through the multilayer composite walls. The wall inner surface is subjected to convective boundary condition and the wall outer surface is subjected to periodic surface temperature boundary condition. The problem was solved by using finite volume method with Tri-Diagonal Matrix Algorithm (TDMA) and fully implicit scheme was chosen. For code validation purposes, a program code for solving transient heat conduction through a one-layer wall was developed and it was used to solve two different types of boundary conditions, the step change in surface temperature and the surface convection. The results obtained were compared with the analytical solutions. Later, a program code for solving unsteady-state heat conduction through a multilayer composite wall, which was incorporated with convective boundary condition on the wall inner surface and periodic surface temperature boundary condition on the wall outer surface, was developed. By using the program, the wall inner surface temperature at any time of a day was determined. Time lags and decrement factors of the composite walls were also calculated. The effects of the thermophysical properties and thickness of the walls were investigated. From the results obtained, it was found that the thermal conductivity, specific heat and the thickness have a very deep effect on the time lag and decrement factor. The investigations were repeated for different wall materials and thickness and the results were discussed.