Extending the heat flux limit with enhanced microchannels in direct single-phase cooling of computer chips

The high heat transfer coefficients in microchannels are attractive for direct cooling of computer chips requiring high heat-flux removal. However, this is associated with a severe pressure drop penalty. Channel size optimization therefore becomes necessary in selecting an appropriate channel geometry configuration. As the heat flux increases beyond about 2 MW/m², the heat transfer and pressure drop characteristics of the plain channels dictate the use of turbulent flow through the channels, which suffers from an excessive pressure drop penalty. It therefore becomes essential to incorporate enhancement features in the microchannels and multiple passes with shorter flow lengths to provide the desired solution. Results obtained from a theoretical analysis are presented as parametric plots for the heat transfer and pressure drop performance of a 10 mm×10 mm silicon chip incorporating plain microchannels. Enhanced microchannels with offset strip fins in single-pass and split-flow arrangements are also investigated. The results show that the enhanced structures are capable of dissipating heat fluxes extending beyond 3 MW/m² using water as the coolant in a split-flow arrangement with a core pressure drop of around 35 kPa.