The cooling or thermal management issues are facing critical challenges with the continuous miniaturization and rapid increase of heat flux of electronic devices. Significant efforts have been made ...to develop high-efficient cooling and flexible thermal management solutions and corresponding design tools. This article reviews the latest progress and the state-of-the-art in electronic cooling, which could help inspire future research. The commonly used methods in electronic cooling, classified into direct and indirect cooling, are reviewed and discussed in detail. Direct cooling consists of air cooling, spray and jet impingement cooling, immersion cooling, and droplet electrowetting. As for indirect cooling, the most popular and hot topics of using microchannel, heat pipe, vapour chamber, thermoelectric, and PCM are overviewed. The effectiveness of the thermal management methods for different-level requirements of electronic cooling and the ways how heat transfer capability can be improved are also introduced in detail. Meanwhile, the pros and cons of these thermal management methods are discussed based on their inherent heat transfer performances/characteristics, optimisation methods, and relevant applications. In addition, the current challenges of electronic cooling and thermal management technologies are explored, along with the outlook of possible future advances.
•Thermal optimization of the fin geometry was performed using the Taguchi and ANOVA.•Correlation equations were formulated for amplifier temperature and fin volume.•The order of importance of the fin ...parameters for temperature and volume was determined.•By optimizing, the amplifier temperature decreased by 8.31% and 51.91% of material was saved.•The most effective parameters on the amplifier temperature and fin volume were determined.
In the rapidly advancing field of electronic power supplies, managing thermal performance is critical. This study focuses on optimizing fin geometries to enhance the thermal management of an amplifier used in car multimedia systems, utilizing Taguchi and ANOVA methods for both thermal and volumetric efficiencies. Analyses were conducted on the impact of five distinct fin parameters—fin gap, fin thickness, separated plate thickness, fin base thickness, and fin height—on the system’s thermal behavior and the fin volume. Computational Fluid Dynamics (CFD) analyses were performed for 24 different configurations. These analyses showed significant potential for improvement in the original design, with optimizations leading to an 8.31% reduction in the amplifier temperature and a 51.91% reduction in the fin volume. The study identifies fin height as the most effective parameter on the amplifier temperature, with an effect rate of 57.26%, while fin base thickness showed the most significant effect on the fin volume, with an effect rate of 66.98%. These findings not only provide a basis for more efficient design but also offer predictive insights through formulated regression equations, thus reducing the dependency on extensive experimental setups.
•Recent studies performed on use of nanofluids in electronics cooling are reviewed.•Directions for future research and challenges existing in this area are presented.•Employing nanofluids can ...considerably improve electronics cooling in the future.
With increase of heat generated by new electronic components, a combination of nanofluid characteristics and minichannel attributes has been introduced as a hot research topic. Development of such technology can result in further miniaturization of electronic equipment and also improve energy efficiency. In this article, the recent studies performed on use of nanofluids in electronics cooling are reviewed considering several aspects such as liquid block type, numerical approach, nanoparticle material, energy consumption, and second law of thermodynamics. Besides, some interesting aspects about employing nanofluids in cooling of electronic components are introduced. Furthermore, the opportunities for future studies as well as the challenges existing in this field are presented and discussed. It is found that applying nanofluids as novel coolants in different liquid blocks and heat pipes can considerably improve electronics cooling technology in the future.
The heat transfer characteristics of a miniatured flat heat pipe (MFHP) with multi-channels, featuring a port diameter of 1.18 mm, is investigated experimentally. Various operating parameters are ...considered, including the working fluid volume (Vf = 1.5, 2.5, and 3.5 ml), length of the liquid reservoir (Lres = No reservoir, 5, and 10 mm), orientation such as axial face (αa) or lateral side (αl), inclination angles (α = −15 to 90o), and cooling water flow rates (ṁi = 10, 15, and 20 LPH). Based on the experiments, the optimal values for the working fluid volume, reservoir length, and flow rate are determined as Vf = 2.5 ml, Lres = 5 mm, and ṁi = 20 LPH, respectively. Further analysis reveals that, the heat dissipation rate for the axial face is significantly higher than that of the lateral side, with an average percentage increase of 35.4 %. However, the lateral side outperforms the axial face in terms of stabilizing the evaporator wall temperature, reducing fluctuations by an average of 24.5 %. Moreover, the presence of multi-channels allows the MFHP in axial face orientation to dissipate a maximum heat load of 15 W against gravity at an inclination angle of αa = −15o. Finally, the variations in MFHP operation based on the orientation and its underlying physical mechanisms that contribute to enhancing heat transfer are discussed.
The thermal performances of a minichannel heat sink are experimentally investigated for cooling of electronics using nanofluid coolant instead of pure water. The Al2O3–H2O nanofluid including the ...volume fraction ranging from 0.10 to 0.25vol.% was used as a coolant. The effects of different flow rates of the coolant on the overall thermal performances are also investigated. The flow rate was ranged from 0.50 to 1.25L/min as well as the Reynolds number from 395 to 989. The coolant was passed through a custom made copper minichannel heat sink consisting of the channel height of 0.8mm and the channel width of 0.5mm. The experimental results showed the higher improvement of the thermal performances using nanofluid instead of pure distilled water. The heat transfer coefficient was found to be enhanced up to 18% successfully. The nanofluid significantly lowered the heat sink base temperature (about 2.7°C) while it also showed 15.72% less thermal resistance at 0.25vol.% and higher Reynolds number compared to the distilled water.
The ever-increasing performance of thin portable electronic products has made their heat dissipation issues more and more severe, or even become failure. A novel 0.5 mm thick ultra-thin vapor chamber ...(UTVC) with six spiral woven meshes and single-layer mesh acting as the wick is developed for cooling portable electronic products. The heat load capacity of the UTVC could be improved through the mixed effect of the spaced structure and composite wick by both decreasing the pressure drop of vapor flow and the fluid flow. The UTVC is tested in five typical positions, and the results show that it can withstand heating power of 10.5 W, 10 W, 10 W, 10 W, and 9.5 W in gravity, horizontal, side, inverted and antigravity positions, respectively, implying that the influence of position on the heat transfer performance of the proposed UTVC is not significant. The effective thermal conductivity of the vapor chamber in the gravity position reaches about 18,000 W/m·K. Compared to the thermal module without UTVC, the one with UTVC has effectively improved the cooling effect of thin electronics and eliminated the hot spots.
•The 0.5 mm vapor chamber can withstand a heating power of about 10 W.•The maximum ke of the vapor chamber is up to 18,000 W/m·K in gravity position.•Thermal module with UTVC can improve heat dissipation capacity and eliminate hot spots.
•Dynamic flow boiling instabilities in microchannel heat sinks are investigated.•Experiments are performed with controlled system compressibility.•Effects of pressure drop oscillations and parallel ...channel instabilities are characterized.•These instabilities are found to have minimal impact on surface temperatures.•Critical heat flux is found to be insensitive to the occurrence of instabilities.
Microchannel flow boiling heat sinks that leverage the highly efficient heat transfer mechanisms associated with phase change are a primary candidate for cooling next-generation electronics in electric vehicles. In order to design flow boiling heat sinks for such practical applications, one key obstacle is an understanding of the conditions for occurrence of dynamic two-phase flow instabilities, to which microscale flow boiling is particularly susceptible, as well as their impact on heat transfer performance. While mapping the operational regimes of these instabilities has been well-studied, with numerous stability criteria available, their impact on the heat transfer performance of heat sinks in practical applications is not understood. This work seeks to assess the impact of pressure drop oscillations and parallel channel instabilities on the surface temperature and critical heat flux in parallel microchannel heat sinks. This is achieved through measurement of time-averaged steady-state temperatures and pressures, combined with high-frequency pressure signals and high-speed flow visualization. These data are compared across three controlled flow configurations that comprise a condition of stable flow boiling, a condition where only parallel channel instabilities can occur, and a third where both pressure drop oscillations and parallel channel instabilities can occur. Experiments are performed using the dielectric refrigerant HFE-7100 in 2 cm long parallel microchannel heat sinks with square-cross-section channels (0.25, 0.5, 0.75, and 1 mm widths) at three mass fluxes (100, 400, and 1600 kg/m2s). Across this range of conditions, the time-averaged surface temperature and critical heat flux were remarkably insensitive to the occurrence of these instabilities despite the significant hydrodynamic events and transient flow patterns observed.
•A novel 3D flat-plate oscillating heat spreader (3D-FPOHS) was fabricated and investigated.•The average maximum temperature could be maintained at 75.5 ℃ under the heat input of 600 W.•A system ...thermal resistance of about 0.09 ℃/W was achieved at the heat flux of 66.7 W/cm2.•The 3D-FPOHS exhibited gravity-independent performance at relatively high heat loads.
The development of thermal management technologies towards localized heating areas characterized by high heat flux densities has become paramount for the secure operation of electronic devices. For the heat dissipation of high-power-density electronic chips, this article developed an aluminum-based three-dimensional flat-plate oscillating heat spreader (3D-FPOHS) integrating a heat-targeting channel layout design. The 3D-FPOHS can absorb heat at the central region on one side and dissipate heat at the entire area of the other side with the aid of a novel radial interconnected dual-layer channel structure. R1336MZZ was used as the working fluid at a volumetric filling ratio of 40 %. The average maximum temperature of the simulated chip could be maintained at 75.5 ℃ under the heat input of about 600 W (or 67 W/cm2), 9.7 ℃ lower than that of the empty device. The 3D-FPOHS exhibits nearly gravity-independent heat transfer performance at high heat inputs greater than 300 W, having a system thermal resistance of about 0.09 ℃/W at the heat input of 600 W. The 3D-FPOHS shows approximately same start-up performance under gravity-assisted and anti-gravity conditions. This study confirms the potential of 3D-FPOHS acting as an integrated cooler for electronic devices, providing a promising option for temperature control of high-power density heat dissipation both under gravity-assisted and anti-gravity conditions.
•A hierarchical manifold microchannel heat sink is fabricated and tested in two-phase operation.•A thin film, serpentine heater provides uniform heating over 5mm×5mm area.•An array of sensors ...monitors the device temperature field.•Heat sinks with high-aspect-ratio microchannels are etched in silicon for intrachip cooling.•Heat fluxes up to 910W/cm2 are dissipated using the dielectric fluid HFE-7100.
High-heat-flux removal is necessary for next-generation microelectronic systems to operate more reliably and efficiently. Extremely high heat removal rates are achieved in this work using a hierarchical manifold microchannel heat sink array. The microchannels are imbedded directly into the heated substrate to reduce the parasitic thermal resistances due to contact and conduction resistances. Discretizing the chip footprint area into multiple smaller heat sink elements with high-aspect-ratio microchannels ensures shortened effective fluid flow lengths. Phase change of high fluid mass fluxes can thus be accommodated in micron-scale channels while keeping pressure drops low compared to traditional, microchannel heat sinks. A thermal test vehicle, with all flow distribution components heterogeneously integrated, is fabricated to demonstrate this enhanced thermal and hydraulic performance. The 5mm×5mm silicon chip area, with resistive heaters and local temperature sensors fabricated directly on the opposite face, is cooled by a 3×3 array of microchannel heat sinks that are fed with coolant using a hierarchical manifold distributor. Using the engineered dielectric liquid HFE-7100 as the working fluid, experimental results are presented for channel mass fluxes of 1300, 2100, and 2900kg/m2s and channel cross sections with nominal widths of 15μm and nominal depths of 35μm, 150μm, and 300μm. Maximum heat flux dissipation is shown to increase with mass flux and channel depth and the heat sink with 15μm×300μm channels is shown to dissipate base heat fluxes up to 910W/cm2 at pressure drops of less than 162kPa and chip temperature rise under 47°C relative to the fluid inlet temperature.
•Jet impingement is compared against other cooling methods for electronic devices.•Role of wettability engineering in enhancing heat flux removal is analyzed.•Experiments with various cooling fluids ...on nonuniform surfaces are summarized.•Effects of wettability and surface science on jet impingement cooling are discussed.•Industrial retrofits and methods to make more durable surfaces are reviewed.
The rising requirements of computing capability with an ever-declining packaging volume has triggered a global surge in the thermal management industry of electronic devices over the past several years. It is of utmost importance to maintain the electronic chip temperature below a specified limit, as overheating may lead to performance degradation, chip failure, and even operational hazards in extreme situations. Numerous attempts to meet the high cooling requirements of the heat-dissipating chips have been made using various devices and techniques, like heat pipes, pool boiling, microchannel heat sinks, spray cooling, jet impingement (JI), etc. Among these, the JI technique has several advantages in the efficient removal of heat in comparison to other approaches. Certain parameters play significant roles in heat removal by jet impingement. For example, coolant (working liquid) properties, flow arrangement (single-phase/multi-phase, laminar/turbulent flow), and target surface thermal and chemical properties are important actors. For both direct and indirect types of JI cooling, the surface properties of the target substrate are among the most essential and controllable features for enhancing heat removal. This paper emphasizes the importance of wettability engineering of the target substrate and presents a critical and comprehensive review of several possible surface engineering techniques that have been adopted by researchers to enhance heat transfer rates from electronic devices via JI cooling. A futuristic outlook on why and how the JI technology can be used in industry is also presented. Challenges abound and in view of this realization, intense R&D efforts are required in this arena.
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