Immersion cooling of electronics utilizing lotus-type porous copper

This paper evaluates boiling heat transfer performance on a lotus-type of porous copper attached on a heated surface. The experiments are performed under atmospheric and saturated pool conditions. The lotus porous medium has uni-directional pore structure and the average size of the pore hole is 0.4 mm. The porous plate of 1.0 mm or 2.0 mm in thickness is mechanically attached onto the heated surface in order to obtain the referential data of this porous media. The boiling curves suggest that utilization of the lotus porous medium definitely leads to boiling heat transfer enhancement. For instance, at the wall superheat of 10 – 20 K, the boiling heat transfer coefficient is 2 – 3 times higher than that of the bare surface. In the low wall superheat regime, the heat transfer coefficient also increases with increasing wall superheat. On the other hand, the results also verify that the thickness of the lotus porous doesn't affect the boiling heat transfer coefficient at all, which suggests that there is a big contact thermal resistance between the heated surface and the lotus plate. In that sense, it is predicted that the boiling phenomena is conceivably dominant mainly at the bottom of the lotus porous. In addition, it is confirmed that the critical heat flux is almost the same as that in the bare surface case, which also indicates us that it needs to enhance the liquid supply toward the inside the lotus porous.