Abstract
The flow pattern based flow boiling heat transfer and two-phase pressure drop models for CO 2, recently developed by Cheng et al. [L. Cheng, G. Ribatski, J. Moreno Quibén, J.R. Thome, New prediction methods for CO 2 evaporation inside tubes: Part I – A two-phase flow pattern map and a flow pattern based phenomenological model for two-phase flow frictional pressure drops, Int. J. Heat Mass transfer 51 (2008) 111–124; L. Cheng, G. Ribatski, J.R. Thome, New prediction methods for CO 2 evaporation inside tubes: Part II – An updated general flow boiling heat transfer model based on flow patterns, Int. J. Heat Mass transfer 51 (2008) 125–135], have been used to predict the thermal performance of CO 2 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 microprocessor. First, some simulation results of CO 2 flow boiling heat transfer and two-phase pressure drops in microscale 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 2 were performed for the following conditions: base heat fluxes from 20 to 100 W/cm 2, a mass flux of 987.6 kg/m 2s and a saturation temperature of 25 °C. These show that the base temperatures using CO 2 are much lower than those using R236fa. Compared to R236fa, CO 2 has much higher heat transfer coefficients and lower pressure drops in the multi-microchannel evaporator. However, the operation pressure of CO 2 is much higher than that of R236fa. Based on the analysis and comparison, CO 2 appears to be a promising coolant for microprocessors at low operating temperatures but also presents a great technological challenge like other new cooling technologies.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
