Performances of Two-Phase Cooling Technologies that Uses Water as Working Fluid under Sub-Ambient Pressures

Two-phase liquid vapor cooling is a promising technology option to achieve enhanced heat removal from integrated circuit components, which can drastically outpace its single-phase counterparts by leveraging the latent heat of the fluid. However, its application has been limited due to its inherent system complexity and relative system instability. The two-phase cooling control loop that provides the ability to sustainably utilize much less expensive working fluids such as water with far superior heat-transfer coefficients compared to traditional single-phase approaches has been revisited as a solution option for addressing the ever-increasing thermal demand placed on electronic components. Also, since typical integrated circuit components require the die temperature to remain below junction temperature, usually at or below 100°C, the system pressure should be maintained below atmosphere such that the saturation temperature of water can be reduced well below 100°C.The current study evaluates the pressure drops and heat transfer characteristics of water coolant flow at sub-atmospheric pressures for two different cooling configurations: 1) bare-die under jet impingement flow showcasing effective heat transfer coefficient well over 10 W/cm ² -°C and 2) microchannel cold plate with thermal resistances less than half that of single-phase cooling with similar flow conditions. It has been demonstrated under variable flowrate and heat-flux conditions leveraging a sub-ambient pressure environment coupled with specific fluid preheating and pressurizing differential conditions, very capable and sustainable thermal cooling performance can be achieved for both configurations.