Improving thermal performance of micro-channel electronic heat sink using supercritical CO2 as coolant

Abstract

Original scientific paper https://doi.org/10.2298/TSCI161110030SIn view of increasing tendency of power density of electronic systems, cooling performance improvement of micro-channel heat sink is an emerging issue. In the present article, supercritical CO 2 is proposed as a heat transfer fluid in micro-channel heat sink for power electronics cooling. Energetic and exergetic performance analyses of micro-channel heat sink using supercritical CO 2 have been done and compared with conventional coolant, water. To take care of sharp change in properties in near critical region, the discretization technique has been used for simulation. Effects of both operating and geometric parameters (heat flux, flow rate, fluid inlet temperature, channel width ratio, and channel numbers) on thermal resistance, heat source (chip) temperature, pressure drop, pumping power and entropy generation are presented. Study shows that the thermal resistance, heat source temperature and pumping power are highly dependent on CO 2 inlet pressure and temperature. Supercritical CO 2 yields better performance than water for certain range of fluid inlet temperature. For the studied ranges, maximum reduction of thermal resistance by using CO 2 is evaluated as 30%. Present study reveals that there is an opportunity to use supercritical CO 2 as coolant for power electronic cooling at lower ambient temperature.

Increasing the efficiency of a Peltier device by assessing the thermal performance of liquid-cooled microchannel heat sinks

“…This gives a preliminary insight as to which coolants are better for use in the AWG system's heat sink. The papers which used the Al2O3/H2O Nanofluid, Transcritical CO2, Supercritical CO2 coolants for their experiments, did not provide such data for analysis [26][27][28][29][30].…”

“…The TiO2/H2O nanofluid's dynamic viscosity was not provided and thus, it cannot be concluded from this data whether it is a more suitable coolant than the Galinstan. [26,30] (c) The required pumping power of supercritical CO2 is plotted against the thermal resistance [30].…”

“…This result suggests that supercritical CO2 would be the most suitable coolant in for the heat sink with the lowest recorded thermal resistivity of 0.094 K W -1 . Figure 10(c) depicts the effect of the thermal resistance on the pumping power of supercritical CO2 at a velocity of 2 m s -1 [30] and thus can be compared against Figure 10(b) to determine whether supercritical CO2 or Galinstan is the most superior coolant for the heat sink. In Figure 10(b), at the lowest point of thermal resistance, 0.054 K W -1 for Galinstan, the pumping power is at a maximum of 0.001 W. From Figure 10(c), the lowest point of thermal resistance for supercritical CO2 is 0.064 K W -1 where the pumping power is also at a maximum, at approximately 0.277 W. These values demonstrate that to achieve a low thermal resistivity, supercritical CO2 requires approximately 0.276 W more pumping power than the Galinstan coolant.…”

Numerical study on the mixing characteristics under transcritical and supercritical injection using large eddy simulation

“…They showed that thermal disintegration may dominate classical mechanical breakup when the fluid temperature close to the pseudo-boiling point. More extensive numerical investigations of the state of knowledge on supercritical mixing and combustion are available in literature [16][17][18][19][20][21][22].…”

Thermodynamic performance analysis of supercritical CO2 Brayton cycle

“…S-CO 2 also has gas characteristics, low viscosity, strong fluidity, low cycle loss of the system, and there is no phase transition in the cycle. S-CO 2 also has the characteristics of non-toxicity, non-flammability, good chemical stability, environmental friendliness and low cost [1][2][3]. Another important feature of S-CO 2 Brayton cycle is its high efficiency in large temperature range.…”