Experimental Study On Flow And Boiling Heat Transfer Of Power-law Fluid In Porous Media

In this paper,the experiment of power law fluid flowing and boiling heat transfer characteristics in porous media is studied.The porous medium is made up of 5mm brass balls.The X-Y plane and X-Z plane are arranged in-line,well Y-Z plane arranged crossing,forming 5X5X62 granular bed.The power law fluid is AP-180 type polyacrylamide.Limited to the porous media,a universal power law fluid experiment platform can be built to realize the flow and heat transfer experiments between 20-150 degrees centigrade,for arbitrary power-law fluid or non-Newtonian fluid and water.At the same time,the size,material and stacking way of porous medium can also be changed to a certain extent.Before the experiment,basic physical parameters of some materials and power-law fluid are measured in advance,such as thermal conductivity,consistency coefficient,boiling point and rheological properties,etc.The experimental conditions consist of the type of solution,the concentration of solution,the temperature,the heat flux and the flow rate.During the experiment,the temperature is measured by a thermocouple,the pressure is measured through a pressure gauge,and the experimental phenomena are recorded by high speed photogrammetry.Finally,the relevant conclusions of power-law fluid flow and boiling heat transfer in porous media are summarized through the data obtained.The flow experiment mainly studies the relationship between the flow particle Reynolds number and the pressure difference between the inlet and outlet of the test end,and the relationship between the pore Reynolds number and the friction coefficient.It is found that,in the same condition,the flow particle Reynolds number is proportional to the pressure drop.The water shows a linear function relationship,and the polyacrylamide solution shows quadratic function relationship.The higher the temperature is,the greater the pressure drops.Under the same condition,the pore Reynolds number is inversely proportional to the friction resistance coefficient in water and the polyacrylamide solution.Both of them are inverse proportional function relationship.At the same pore Reynolds number,the higher the temperature of,the greater the frictional resistance coefficient.At the same pore Reynolds number,the higher the concentration,the greater the coefficient of friction resistance.The boiling heat transfer experiment mainly observed the experimental phenomenon of boiling heat transfer in the test section of the porous medium,and observed the change trend of the gas-liquid interface line during the fluid boiling heat transfer experiment by the change of the working condition.Also the heat transfer coefficient between the heating purple copper plate and the fluid in each position of the test section is calculated.It is found that the lower the concentration,the lower the flow velocity,the greater the density of the heat flow,the larger the percentage of the volume of the gas,which can produce more bubbles,and the boiling phenomenon is more obvious.The boiling heat transfer coefficient decreases along the direction of fluid flow,and the variation curve is similar to the inverse function.