Two phase convective cooling for ultra-high power dissipation in microprocessors

We present results of modeling for the design of microgaps for the removal of high heat fluxes, i.e., 1 kW/cm², at low wall temperature (~ 85°C) via a strategy of very high mass flux (>1000 kg/m²s), high quality (outlet vapor mass quality >90%), two-phase forced convection. Modeling includes (1) thermodynamic analysis to obtain performance trends across a wide range of candidate coolants, (2) evaluation of worst-case pressure drop due to contraction and expansion in inlet/outlet manifolds, and (3) 1-D reduced order simulations to obtain realistic estimates of different contributions to the pressure drops. The main result is the identification of a general trend of improved heat transfer performance at higher system pressure at the cost of reduced achievable system efficiency (COP), with important implications for coolant selection and system design.