ОСОБЛИВОСТІ ТЕПЛООБМІНУ В ПЛАСКОМУ ПОРИСТОМУ МІКРОКАНАЛІ

• Date: 2020
• Main Authors: Avramenko, A.A., Dmitrenko, N.P., Kovetska, Yu.Yu., Kondratieva, E.A.
• Format: Article
• Language: Ukrainian
• Published: Institute of Engineering Thermophysics of NAS of Ukraine 2020
• Online Access: https://ihe.nas.gov.ua/index.php/journal/article/view/375
• Journal Title: Thermophysics and Thermal Power Engineering

A steady heat transfer process of mixed convection in a flat vertical porous microchannel is considered. The results of simulation showed that Knudsen number effects are more significant in the neighborhood of the wall where growth of Knudsen numbers is accompanied with the velocity and temperature jumps on wall. With increasing parameter of porosity M (decreasing permeability), the flow velocity decreases and the velocity jump decrease as well. For all combinations of the criteria Ra, Kn and M increasing Knudsen number reduces heat transfer intensity. This can be attributed to increasing temperature jump on wall which causes deterioration of thermal interaction between the fluid and the wall. For low Rayleigh numbers increasing parameter M leads to increasing heat transfer since the temperature jump decrease on walls. For large Rayleigh numbers the trend becomes reversed, since for larger parameters M, the near-wall velocity decreases. For low Rayleigh numbers increasing the Knudsen number leads to decreasing hydraulic resistance coefficient, but with increasing parameter M leads to increasing this coefficient. At high Ra numbers increasing Knudsen number leads to growth of hydraulic resistance, which is due to increasing velocity gradient on the wall.