Conjugate Heat Transfer Using Liquid Metals and Alloys for Enclosures With Solid Conducting Blocks

Abstract

A validated computational model was created to simulate the heat transfer from a heated surface using liquid metals and alloys during conjugate heat transfer. This model explores the effect of the Rayleigh number, Prandtl number, thermal conductivity ratio, and aspect ratio on the Nusselt number along the hot surface. The data will show how to keep the temperature sensitive components along the hot wall cool by maximizing the amount of heat removed from the hot wall. The data show three distinct regions that occur as a function of the Rayleigh number for a fixed k∗ and d∗. The data also show that the thermal conductivity ratio between the fluid and the solid conducting block has little effect on the Nusselt number at a fixed Rayleigh number. However, when examining the effect of the aspect ratio on the Nusselt number, two distinct regions can be seen. The results demonstrate that in order to keep the temperature sensitive components cool along the hot wall, one would want to have large Rayleigh and Prandtl numbers. The easiest way to achieve large Rayleigh numbers is by increasing the height of the enclosure. Large Prandtl numbers can be achieved by choosing a fluid that is highly conductive. In addition, the choice of material for the center solid conducting block does not impact the amount of heat removed from the hot wall. However, increased cooling can be achieved by decreasing the spacing between the hot and the cold wall.