The Natural Convection Experiment Of Metal Foam-water In Cavtity

With the advance in technology updating the material,people take more attentions on energy saving in the field of industry of heat transfer.Metal foam is a new energy-saving material. It is used widely in aviation and industry about enhancing heat transfer, Which relates to the natural convection of a closed cavity filled with porous medium,and the study of its heat transfer characteristics become hot subject in porous medium filed.In this paper, an apparatus of metal foam-water is built which occur natural convection.The temperature distribution in metal foam,the phenomenon of local non-thermal equilibrium and the influence on natural convection heat transfer are investigated.The influence includes external factors:heating power,the inclined angle of cavity and cooling water flow rate.Which includes internal factors also:pore density and porosity of metal foam.The relevant of experimental results is obtained.The addition of metal foam enhance heat transfer 1.26 times under the experimental conditions. It exists the phenomenon of local nonthermal equilibrium. At high power, the temperature difference of solid and fluid can reach3.5 degree in some position. Under the influence of external factors, the increase in the heating power can be enhanced heat transfer. Natural convection heat transfer with the inclination angle increases. Changing the cooling water flow rate does not affect the natural convection heat transfer. Under the influence of internal factors,the natural convection heat transfer decrease with the increasing metal foam pore density porosity. The reason is that increasing pore density lead pore diameter decreasing in a certain porosity. The fluid flow is blocked in smaller pore diameter, which makes the natural convection heat transfer weakened.When porosity increases, reducing the metal content, thermal conductivity decreased, making the overall natural convection heat transfer weakened. At the same time the experimental data analysis are summarized. A correlation equation of natural convection heat transfer which contains the structure parameters of metal foam is obtained. The correlation equation is:。...