Vapor chamber forced convection cooling using flow boiling in open microchannels and tapered manifolds

A microchannel flow boiling system is proposed, having a vapor chamber allowing for fluid condensation, with flow driven by a low-power pump. A gravity-driven flow configuration using ethanol in open microchannels and tapered manifolds was developed and tested previously using ethanol. This work extends the testing to develop performance characterization curves for the system at the desired flow rates. The low pressure drop, low flow rate system is highly efficient, requiring very minimal pumping power, due to the gravity-assisted nature of the flow. The configuration can be replicated at lower flow rates in a configuration similar to a thermosyphon loop, or with a low power pump. Higher performance beyond that of pool boiling is achieved in this configuration, with a low pressure drop, resulting in low power consumption. Pressure drop and flow rate dependence of system performance as well as overall system effectiveness is described by performance characterization curves, developed in the present work. The effects of the tapered manifold and the open microchannels are essential to the system performance, as they produce a remarkably low pressure drop, particularly at high heat flux.