MS THESIS PRESENTATION: THREE-DIMENSIONAL MODELING OF HEAT TRANSFER AND FLUID FLOW IN A FLAT GROOVED MICRO HEAT PIPE
Cem Kurt
MS Student
(Supervisor: Assoc. Prof. Dr. Barbaros Çetin)
Mechanical Engineering Department
Micro heat pipes (MHP) are widely used in many applications from thermal management of electronic devices to space industry due to their robustness and ability of dissipating heat from the system effectively and reliably. MHP is basically a container with micro grooves on the inner surfaces, and essentially a bridge that can transfer large amount of thermal energy between a heat source and a sink with small temperature differences by utilizing the phase change mechanism of the working fluid. Heat source evaporates the working fluid in the one end of the grooves, and due to the emerging pressure difference, the composed vapor flows to the heat sink region in the other end. Then the vapor condenses back into the grooves before it flows to the evaporation region by the capillary force and repeat the cycle. Mathematical modeling of heat transfer and fluid flow of MHP’s is crucial to understand the effects of many parameters (dimensions, groove shape, working fluid filling ratio, material types) on their operational limits in order to design case-specific heat pipes. In the literature, many models are presented with some simplifications and assumptions. In this thesis, a computational methodology is proposed that models the heat transfer and fluid flow fully in 3D for the first time, by using COMSOL Multiphysics® via LiveLink™ for MATLAB® interface. Combining the flexibility of script environment of MATLAB with the benefits of using energy and momentum solvers of a commercial software gives a powerful and practical tool that can overcome great difficulties if this modeling was to be done in a CFD software or an in-house code alone. In the presented model, radius of curvature (R) variation of the working fluid in the groove, temperature gradient of the groove wall (Tw), and vapor temperature (Tv) are the essential working parameters of a heat pipe that reflects the efficiency. In this methodology, these variables are estimated initially, and are calculated by a set of interbedded and subsequent iterations. The momentum equations are solved for the iteration of R, the energy equations are solved for Tw iteration, and lastly Tv is calculated by the secant method using the conservation of mass. Depending on the values of the variables, the solution domain is re-generated and the phase change boundary conditions are re-calculated at each iteration.
DATE: 09 September 2019, Monday @ 16:00
PLACE: EA-409
Yelda İrem Ateş
Faculty of Engineering
Administrative Assistant
Tel : +90 (312) 290-2351
Fax: +90 (312) 266-4126