Event Details
Numerical Modeling of Thermal Processes
Presenter: Wei Liu - M.A.Sc Candidate
Supervisor:
Date: Wed, May 30, 2001
Time: 14:00:00 - 15:00:00
Place: EOW 430
ABSTRACT
Abstract:
A coupled EM-thermal engine needs to be applied to solve the thermal problems in microwave engineering. For example, waveguide components usually contain discontinuities that give rise to reflection and storage of energy. This storage of energy is always combined with wall losses that increase the temperature near the discontinuities. In fact, the temperature can become so high that the components be destroyed.
A new approach has been implemented to solve such problems. In the designed thermal engine, heat conduction is formulated using an explicit FDTD algorithm, with the temperature dependence of thermal conductivity taken into account. The conducting heat energy is not only propagating within one substance, but also transferred from one substance to another substance that has contact with it. Thermal convection in the application of microwave engineering is simplified with the assumption that no forced cooling system is present. Thus only microwave heated walls or dielectric objects cause the natural convection of fluid (usually air) immediately adjacent to it. Thermal radiation in free space is easily formulated with the empirical equations.
The designed thermal engine has been applied to analyze a microwave cavity with a PVC sample placed in the middle. Different source distributions have been tested and the temperature distribution corresponds to their source very well. The thermal analysis tool is very useful in the thermal application of microwave engineering. It allows us to predict the temperature rise, the hot spot, the critical temperature point and optimize the power handling capability.