A review of the thermal performance of vapor chambers and heat sinks: Critical heat flux, thermal resistances, and surface temperatures

2022 ◽  
Vol 183 ◽  
pp. 122108
Author(s):  
Munonyedi Egbo
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Surface Temperatures

scholarly journals Experimental Study on Thermal Performance of a Bent Copper-Water Heat Pipe

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuangshuang Miao ◽  
Jiajia Sui ◽  
Yulong Zhang ◽  
Feng Yao ◽  
Xiangdong Liu
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Critical Heat Flux ◽  
Working Conditions ◽  
Thermal Performance ◽  
Heat Input ◽  
High Heat ◽  
High Heat Flux ◽  
Electronic Components ◽  
Copper Water

Vapor-liquid phase change is regarded as an efficient cooling method for high-heat-flux electronic components. The copper-water bent heat pipes are particularly suited to the circumstances of confined space or misplaced heat and cold sources for high-heat-flux electronic components. In this paper, the steady and transient thermal performance of a bent copper-water heat pipe is studied based on a performance test system. The effects of cooling temperature, working conditions on the critical heat flux, and equivalent thermal conductivity have been examined and analyzed. Moreover, the influences of heat input and working conditions on the thermal response of a bent heat pipe have also been discussed. The results indicate that the critical heat flux is enhanced due to the increases in cooling temperature and the lengths of the evaporator and condenser. In addition, the critical heat flux is improved by extending the cooling length only when the operating temperature is higher than 50°C. The improvement on the equivalent thermal by increasing the heating length is more evident than that by increasing cooling length. It is also demonstrated by the experiment that the bent copper-water heat pipe can respond quickly to the variation of heat input and possesses superior transient heat transfer performance.

Towards a Durable Polymeric Internal Coating for Diabatic Sections in Wickless Heat Pipes

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Fabio Villa ◽  
Marco Marengo ◽  
Joël De Coninck
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Surface Properties ◽  
Critical Heat Flux ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Surface Wettability ◽  
Polymeric Coating ◽  
Stainless Steel Surface ◽  
Power Load

Heat pipe characteristics are linked to the surface properties of the diabatic surfaces, and, in the evaporator, surface properties influence both the onset boiling temperature (TONB) and the critical heat flux (CHF). In this work, the effect of surface wettability in pool boiling heat transfer is studied in order to understand if there could be a path to increment heat pipe thermal performance. This work analyzes the effects of surface wettability on boiling (tested fluid is pure water) and proposes a new super-hydrophobic polymeric coating (De Coninck et al., 2017, “Omniphobic Surface Coatings,” Patent No. WO/2017/220591), which can have a very important effect in improving the heat pipe start-up power load and increasing the thermal performance of heat pipes when the flux is lower than the critical heat flux. The polymeric coating is able to reduce the TONB (−11% from 117 °C to about 104 °C) compared with the uncoated surfaces, as it inhibits the formation of a vapor film on the solid–liquid interface, avoiding CHF conditions up to maximum wall temperature (125 °C). This is realized by the creation of a heterogeneous surface with superhydrophobic surface (SHS) zones dispersed on top of a hydrophilic surface (stainless steel surface). The proposed coating has an outstanding thermal resistance: No degradation of SH properties of the coating has been observed after more than 500 thermal cycles.

Constrained Optimization of One-Dimensional Two-Phase Flow in Fractal-Like Branching Microchannel Heat Sinks

2011 ◽  
Author(s):  
Douglas B. Heymann ◽  
Deborah V. Pence
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Wall Temperature ◽  
Two Phase Flow ◽  
Heat Sinks ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Temperature Constraint ◽  
Flow Through

The performance of two-phase flow through fractal-like heat sinks, subject to both geometrical and flow constraints was assessed. Constraints are crucial in order to satisfy physical requirements of a design. A one-dimensional model of two-phase flow through fractal-like branching microchannels was used to estimate pressure drop, wall temperature and critical heat flux. Water is employed as the working fluid. The exit pressure is varied between 6 kPa and 101.3 kPa (absolute) in order to achieve two-phase flow at temperatures lower than the maximum wall temperature constraint of 70°C. Preliminary results show that the benefit to cost ratio of two-phase flow is on the same order of magnitude as single-phase flow, both with a 70°C wall temperature constraint. Alternatively, a critical heat flux model is used to constrain the flow rate in order for the imposed heat flux to be 50% of the critical heat flux.

Experimental Measurements of Critical Heat Flux in Expanding Microchannel Arrays

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Mark J. Miner ◽  
Patrick E. Phelan ◽  
Brent A. Odom ◽  
Carlos A. Ortiz
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Mass Flux ◽  
Flow Boiling ◽  
Heat Sinks ◽  
Maximum Heat ◽  
Maximum Heat Flux ◽  
Expansion Angle ◽  
R 134A ◽  
And Performance

The effect of an expanding microchannel cross-section on flow boiling critical heat flux (CHF) is experimentally investigated across four rates of expansion. A pumped-loop apparatus is developed to boil R-134a in an array of microchannels cut into copper; a test section is designed to facilitate interchange of the microchannel specimens, allowing consistency across experiments. An optimum expansion angle allowing maximum heat flux is observed, the location of which increases with the mass flow rate. The boiling number does not indicate any optimum in the range observed, showing a nearly monotonic increase with expansion angle. The familiar increase in critical heat flux with mass flux is observed, though expansion shifts the CHF-mass flux curves in a favorable direction. The existence of an optimum expansion angle confirms an earlier qualitative hypothesis by the authors and suggests that microchannel heat sinks offer opportunities for methodical improvement of flow boiling stability and performance.

Sign in / Sign up

Export Citation Format

Share Document