FLUID FLOW AND HEAT TRANSFER CHARACTERISTICS IN THE MULTILAYERED-PARALLEL FRACTURED POROUS CHANNEL

Based on the Brinkman-extended Darcy model and the local thermal equilibrium model, the fluid flow and heat transfer characteristics in the multilayered-parallel fractured porous channel are studied. The analytical solutions of velocity field, temperature field in each region of multilayered-parallel fractured porous channel, friction coefficient and Nusselt number are obtained. The effects of the fracture number, Darcy number, hollow ratio and the ratio of effective thermal conductivity on heat transfer characteristics are analyzed. The results show that when Darcy number is small, the Darcy velocity in the porous media which does not change with the porous height increases with the increase of the number of fracture layers, and is not affected by the porous layer position in multilayer porous channel with certain number of fractures. Increasing the number of fracture layers weakens the influence of hollow ratio on pressure drop and increases the fluid pressure drop in the channel, but the increase degree gradually decreases. The increase of the ratio of effective thermal conductivity or decrease of the hollow ratio leads to a stepwise temperature distribution in the multilayered fractured porous channel, while the temperature distribution curves in the multilayered fractured channel tend to be consistent when the thermal conductivity ratio is small or the hollow ratio is large. Furthermore, when the ratio of thermal conductivity is small, the heat transfer effect in multilayered fractured porous channel is better than that in single fractured porous channel at any hollow ratio. However, when the ratio of thermal conductivity is large, there is a critical hollow ratio, which makes the heat transfer effect in the channels with different numbers of fracture layers be the same, and increasing the number of fractured layers has little influence on the heat transfer effect in multilayered fractured porous channel.