Numerical study and experimental validation for enhancement of natural convection by EHD conduction pumping in a narrow rectangular cavity filled with a dielectric fluid

초록

The heat transfer enhancement of natural convection in a narrow rectangular cavity by the electrohydrodynamic (EHD) conduction flow of a dielectric fluid was investigated. In order to investigate low Rayleigh situations in which the EHD effects can lead to a significant enhancement of the natural convection heat transfer, a narrow rectangular cavity with an aspect ratio of 1:10 was studied. To boost the EHD effects, multiple pairs of electrodes were placed on the hot and cold vertical walls of the cavity. The narrow cavity geometry is easily found in the dielectric fluid submerged cooling of the ESS, datacenter and AI accelerator. First, the effects of the number of electrode pairs, the temperature difference, and the applied electric voltage on the heat transfer enhancement were investigated numerically. Next, experimental validations were conducted on a cavity with an 8-pair electrode arrangement under applied voltages up to 1.5 kV. For a heat flux of 500 W/m2 (temperature difference of 5.5 K, Rayleigh number congruent to 42,000) and an applied voltage of 1.5 kV (electric Rayleigh number congruent to 8100), it was revealed that the heat transfer performance in a cavity with the 8-pair electrode arrangement could be increased by 51 % compared to pure natural convection.

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