Cooling of Microprocessors Using Flow Boiling of CO in a Micro-Evaporator: Preliminary Analysis and Performance Comparison

Lixin Cheng , John R. Thome

The flow pattern based flow boiling heat transfer and two-phase pressure drop models for CO, recently developed by Cheng et al. [1, 2], have been used to predict the thermal performance of CO in a silicon multi-microchannel evaporator (67 parallel channels with a width of 0.223 mm, a height of 0.68 mm and a length of 20 mm) for cooling of a micro-processor. First, some simulation results of CO flow boiling heat transfer and two-phase pressure drops in micro-scale channels are presented. The effects of channel diameter, mass flux, saturation temperature and heat flux on flow boiling heat transfer coefficients and two-phase pressure drops are next addressed. Then, simulations of the base temperatures of the silicon multi-microchannel evaporator using R236fa and CO were performed for the following conditions: base heat fluxes from 20 to 100 W/cm, a mass flux of 987.6 kg/ms and a saturation temperature of 25°C. These show that the base temperatures using CO are much lower than those using R236fa. Compared to R236fa, CO has much higher heat transfer coefficients and lower pressure drops in the multi-microchannel evaporator. However, the operation pressure of CO is much higher than that of R236fa. Based on the analysis and comparison, CO appears to be a promising coolant for microprocessors at low operating temperatures but also presents a great technological challenge like other new cooling technologies.

Mots clés: Cooling; Micro-processor; Micro-evaporator; CO; Flow boiling; Heat transfer; Evaporation; Two-phase flow; Pressure drop; Micro-Channel; Chips

Lixin Cheng, John R. Thome. Cooling of Microprocessors Using Flow Boiling of CO in a Micro-Evaporator: Preliminary Analysis and Performance Comparison. Applied Thermal Engineering, 2009, 29 (11-12), pp.2426. ⟨10.1016/j.applthermaleng.2008.12.019⟩. ⟨hal-00528080⟩