Superior Single-Phase Over Two-Phase Liquid Cooling for Thermal Management of Electronic

Semiconductor devices requires temperatures to be below 85°C. This operation temperature constrains the choice of thermal management solutions. To achieve this temperature, single-phase water and two-phase dielectric coolant provide effective thermal management of electronic devices. To date, there is still no definitive evidence indicating which cooling approach is superior to the other one. In the single-phase, sensible heat capacity of water exhibits approximately 2–3 times greater than that of the dielectric coolant. However, when using the dielectric coolant, its latent heat during phase change can be utilized. A comparison of single- and two-phase liquid cooling, on the same microfluidic silicon chips was conducted. The chip temperature was maintained at 85°C while the heat input was increased. Water with a saturation temperature of 100°C was used for single-phase, while HFE-7100 with a saturation temperature of 61°C was used for two-phase cooling. The mass flux was adjusted to maintain a constant 85°C under increasing heat loads. Notably, the two-phase cooling exhibited higher pressure drops due to flow instabilities. It showed that single-phase water showed lower input power than the two-phase HFE7100 for the same target heat flux at the chip temperature of 85°C. Furthermore, single-phase water can remove a higher heat flux under identical mass flux. Our direct comparison shows that single-phase water in plain wall microchannels outperforms two-phase HFE7100 in various structured microchannels at identical heat flux and chip temperature.