Porous media heat exchangers for cooling of high-power optical components

Sintered porous medium heat sink for cooling of high-power mini-devices

“…Most of theoretical models and numerical simulations (Hwang and Chao, 1994;Rosenfeld and North, 1995;Raffray and Pulsifer, 2003;Jiang et al, 2004b) used a particle diameter as one of the basic parameters for calculating both heat transfer and friction in the porous medium of cooling systems. Frequently, advanced electronics, optics, nuclear equipment and high frequency microwaves systems require cooling of some devices at a heat flux of about 5-30 MW/m 2 .…”

Applications of advanced materials technologies to vacuum electronic devices

“…Both techniques have shown the ability to repeatedly absorb heat fluxes well in excess of 3 kW/cm in test components and prototype vacuum electronic devices, with performances reaching the 7.5-10-kW/cm range in short duration tests [44], [47]. However, since the technology of porous metal cooling is still in a relatively early stage, it is difficult to predict the ultimate limits of its capability.…”

“…A relatively new cooling technique uses a porous metal medium to accomplish the transfer of heat from the hot surface to a fluid [47]. One class of porous metal heat exchanger employs a single phase (such as a liquid) which is pumped through the medium.…”

“…One type of porous metal cooling scheme that does not have a conventional technology counterpart is the heat pipe [47]. Heat pipes use passive two-phase heat transfer in a sealed container.…”

“…However, there is a large pressure drop associated with pumping liquids through the porous metal, which is why numerous coolant inlet and exit holes are required. The heat flux capability of a single phase porous heat exchanger can be estimated using the design equation (16) where is the porosity is the local particle to fluid convective heat transfer coefficient, is the effective thermal conductivity of the porous material (also known as the wick), is the surface area of the porous medium (m per m of material), and is the wall-to-fluid temperature drop [47]. Equation (16) assumes a semi-infinite wick thickness normal to the faceplate.…”