The Experimental Study On Heat Transfer And Natural Convection In A Complex Cavity Partially Filled With Porous Medium

Convection and heat transfer in porous media is a phenomenon which is closely related to production and life, it is widespread in nature and industrial such as designing of fuel cells, heat transfer on building enclosure, optimization designing of heat exchanger, process of grain drying, designing and optimizing of solar collector and so on. The nature of these problems is heat transfer and natural convection in a complex cavity partially filled with porous medium, so it is very important to research this phenomenon on the basic theory.In this article, the progress of theoretical analysis, numerical simulation and experiments was introduced first. Then the law of heat transfer and natural convection in a complex cavity partially filled with porous medium was analyzed to building mathematical model and physical model. Thinking about the physical truth of the research object. Because of the influences of the stress slip condition at the interface between porous medium and pure fluid was taken into account on the base, then the law of heat transfer and natural convection in a complex cavity partially filled with porous medium was analyzed. Velocity field and temperature field was obtained to comparison and analysis with the experimental results by using finite element method to numerical simulating,The combination of theoretical analysis, numerical simulation and experiments was used to discuss and analysis the law of heat transfer and natural convection in a complex cavity partially filled with porous medium. The law and influences of f heat transfer and natural convection was study on the influences on the intensity of natural convection Ra, the thickness of the porous medium, porosity and the stress slip condition at the interface.In this article, COMSOL Multiphysics numerical simulation software based on the finite element method was used to simulating,the law of heat transfer and natural convection in a complex cavity partially filled with porous medium was get in different intensity of natural convection Ra, thickness of the porous medium, porosity and the stress slip condition at the interface. Conclusion was get in this research:the existence of the porous medium is block flow and heat transfer in the cavity, the more thickness, the bigger block effect; the more porosity and Ra, the strengthener heat transfer and natural convection in the cavity, the thickness of Porous media and Ra have little impact on stress jump coefficient, when porosity have big impact on stress jump coefficient.At last, a test bench on natural convection in the composite cavity was built to test the law of natural convection in a complex cavity partially filled with porous medium. Construction of the porous medium in the composite cavity was introduced first, then a suitable two-dimensional testing section was selected by numerical simulating. The next, principle of PIV and the process and equipment of the test bench was introduced. At last, Different working conditions of flow field with three different structure of the porous medium model was tested by PIV test bench when wall temperature is constant and a temperature gradient existed in different sides. The influence on flow field was tested in different Ra, thickness of the porous medium, porosity.Finally, the results of experimental and numerical simulation are contrasted and analyzed. Through the experiment, a law is get:Ra, thickness of the porous medium, porosity have big impact on flow in a complex cavity, an accurate description of natural convection in the composite cavity can get by PIV which is one of the best way to visually research the flow in a complex cavity partially filled with porous medium.