Experimental Study On Flow And Heat Transfer Of Power-Law Fluid Based On Rule Arrangement Of Porous Media

In this paper,four different porous media models were established by changing the arrangement of porous media: two kinds of forked,fully centered and cubic center.In experiment,the inlet temperature,the inlet fluid velocity and the concentration of the solutionwere changed.The water and polyacrylamide aqueous solution(PAM solution)were investigated by measuring the pressure and temperature of the inlet and outlet,and the temperature of the hot plate and the internal particles.The relationship between the pressure drop and the friction coefficient and the Reynolds number,the relationship between the local Nusselt number and the Reynolds number,and the influence of temperature,concentration and heat flux on the heat transfer of the PAM solution.The experimental results show that the pressure drop of the porous medium increases with the increase of Reynolds number in the porous medium,and when the Reynolds number is small,the fluid is in Darcy Flow state,cohesive force play a major role;and when the Reynolds number is large,the inertial force plays a major role.When the temperature of the solution is increased,the pressure drop of the water and the PAM solution decreases obviously.The higher the temperature,the greater the pressure drop of the porous medium when the fluid flow rate is large.At the same concentration,the friction coefficient of water and PAM solution decreases with the increase of the Reynolds number.When the fluid velocity is small,the resistance coefficient increases,and the change of the frictional resistance coefficient is very slow.Water and PAM solution in the same conditions,with the flow of particles Reynolds number increases,the local Nusselt number is also increasing.The higher the heat flux of the hot plate,the higher the local Nusselt number of PAM aqueous solutions.As the flow rate of PAM solution through porous media increases,the average heat transfer coefficient is also increasing.At the same flow rate,the surface heat transfer coefficient of the four models decreases with the increase of PAM aqueous solution concentration.With the increase of the flow rate of PAM aqueous solution,the temperature of the lower wall of the heating plate gradually becomes smaller.When ReD <30,the local Nusselt number of model three and model 4 is larger than that of model one and model two.When ReD>60,the local Nusselt number of model three and model fouris obviously smaller than that of model one and model two.