Search Results (119)

Technological development and thermal management are closely related, as chip-based units demand efficient cooling. Microchannel cooling is a key solution. This study, for the first time, experimentally and numerically investigates fin distributions with decreasing numbers, with/without staggered configurations, and the effect of dimples on single-phase flow in micro-pin-finned heat sinks. The database covers mass fluxes from 500 to 750 kg m⁻² s⁻¹ (in 50 increments) and four heat sinks (coded as MH-0, MH-1, MH-2, MH-3), with Reynolds numbers ranging from 234 to 327. Complementary numerical simulations were also employed to visualize flow structures and local Nusselt distributions to elucidate the experimental observations. It was concluded that low-velocity eddies occur in the dimples and between the successive pin-fins. The best thermal performance was obtained for MH-3, while the lowest pressure drop was measured for MH-1. Therefore, if heat transfer is the primary aim, MH-3 is preferred. MH-3 increases average Nusselt Number (Nu_avg) by between 11.45% and 14.38% compared to MH-0. However, the pumping power results underline the importance of MH-1. Compared to MH-0, the pumping power decreases by up to 18.4% for MH-1, 16.6% for MH-2, and 13.8% for MH-3. Full article

Microchannel liquid cooling technology, characterized by high heat-transfer efficiency, represents an effective solution for thermal management in high heat-flux density electronic devices. Existing research has mainly focused on optimizing the structural design of microchannel heat sinks, while neglecting the specific effects of inlet manifold configurations on their heat transfer and flow performance. To obtain more systematic data on microchannel heat transfer performance and internal velocity distribution, this study designed microchannels with single-inlet and triple-inlet configurations. A microchannel cooling performance testing platform was established, and visualization experiments of the internal flow field in straight microchannels were conducted using a particle image velocimetry (PIV) system. The velocity distribution uniformity and heat transfer performance were compared between single-inlet and triple-inlet microchannels with varying channel spacings. The results show that under the same flow conditions, the triple-inlet splitter structure yields a more uniform flow distribution, a lower peak temperature for the heat source chip, and improved heat transfer performance, with its pressure drop reduced to 11.1–26.6% of that of the single-inlet configuration. Furthermore, smaller channel spacings yield improved heat-transfer efficiency in microchannels. Full article

In response to the increasingly severe heat dissipation challenges in electronic devices, three types of manifold microchannel heat sinks (MMC) incorporating rhombic pin-fins were proposed. Under the constraint that the maximum temperature of the heat source surface remains below 343.15 K, numerical comparisons with a conventional straight rectangular microchannel heat sinks (MCHS) reveal that the design featuring a trapezoidal manifold exhibits superior comprehensive thermal performance and improved temperature uniformity. Furthermore, the influence of rhombic pin-fin geometry on thermal performance was investigated for both MCHS with and without the trapezoidal manifold under varying mass flow rates. Results show that for the MCHS without a manifold, performance evaluation criterion (PEC) reaches its maximum when the inlet angle of the rhombic pin-fin is 120°, the side length is 0.17 mm, and the pin-fin height is 0.18 mm. In contrast, for the MCHS with the trapezoidal manifold, optimal PEC is achieved at an inlet angle of 110°, a side length of 0.18 mm, and a pin-fin height of 2.2 mm. Additionally, a multi-objective optimization was conducted using the Latin hypercube sampling method. Three objective functions—maximum temperature (${\mathrm{T}}_{\max }$), thermal performance (PEC), and temperature uniformity (${\mathsf{\sigma }}_{\mathrm{T}}$)—were considered. A total of 150 sample points were used to train Kriging surrogate models for the rhombic pin-fin MCHS with trapezoidal manifold. The optimization results demonstrate a 34.05% enhancement in thermal performance and an 18.6% improvement in temperature uniformity. Full article

Conventional cooling schemes that rely on rigid heat-sink-to-die coupling in vertical stacks fail to track the dynamic, non-uniform heat map of high-performance artificial-intelligence (AI) chips employing chiplet-based heterogeneous integration, giving rise to local hot spots. To eliminate this mismatch, we present a leaf-vein-inspired fractal microchannel tailored for such AI processors. Its hierarchical bifurcation–confluence topology adaptively reshapes the flow field, delivering ultra-low thermal resistance, high heat-transfer coefficients, and uniform dissipation. Coupled with reconfigurable chiplet placement, the design is evaluated through FEM-based orthogonal experiments that rank the influence of coolant, channel diameter/depth, inlet/outlet position, substrate thickness, and flow rate via range analysis and Analysis of Variance (ANOVA). A machine-learned surrogate model of junction temperature is then fed to Particle Swarm Optimization (PSO) for multi-parameter optimization. When re-simulated with the optimal parameter set, the symmetric fractal network lowered the AI chip junction temperature from 127.80 °C to 30.97 °C, a 76% improvement, offering a theoretical basis for hotspot mitigation in advanced heterogeneous AI packages. Full article

This experimental study comparatively investigates flow boiling performance and mechanisms in open and closed rectangular microchannels (ORMs/CRMs) with a high aspect ratio of 4. Fabricated on a copper substrate and sealed with a transparent window for visualization, the systems were tested using refrigerant R245fa. Experiments spanned mass fluxes from 89 to 545 kg/m²·s and heat fluxes from 6.3 to 218.5 W/cm² at an inlet temperature of 14 °C. Flow visualization reveals that the ORM configuration accelerates the transition from bubbly to slug and churn flow regimes and facilitates a unique stratified flow pattern absent in the CRM. Quantitatively, the ORM enhances the heat transfer coefficient by 4.2–14.1% while reducing the system pressure drop by 11.5–58.6% within the low mass flux range (89–269 kg/m²·s). Conversely, at a high mass flux of 545 kg/m²·s, the ORM’s pressure drop increases substantially by 29.9–246.8%, attributed to significant two-phase losses in the top-gap region. As heat flux increases, inertial forces dominate over gravitational effects, shifting the primary heat transfer contribution from nucleate to flow boiling. The figure of merit (FOM) confirms the overall performance superiority of the ORM at low mass fluxes. This work provides valuable insights and design guidelines for high-performance, high-aspect-ratio microchannel heat sinks in advanced thermal management systems. Full article

To address the thermal management challenges of high-heat-flux electronic devices, this study investigates heat transfer enhancement in microchannels with composite cavity-rib triangular prism structures through numerical simulations. Three cavity configurations (arc-shaped, rectangular, and trapezoidal) with depths ranging from 0.2 to 0.35 mm were analyzed. The results reveal that increasing the cavity depth elevated the friction resistance, with the trapezoidal cavities exhibiting the highest increase in friction resistance at Re > 550. The heat transfer performance exhibited a nonlinear improvement with depth: arc-shaped cavities (D = 0.35 mm) achieved maximum Nusselt numbers at low Reynolds numbers, whereas trapezoidal cavities excelled at high Reynolds numbers. The thermal-hydraulic performance evaluation criterion (PEC) identified the arc-shaped cavity (D = 0.35 mm) as optimal, achieving a maximum PEC value of 1.7495, which surpassed the rectangular and trapezoidal configurations by 4.3% and 0.7%, respectively. This study demonstrates that composite cavity-rib structures enhance secondary flow disturbances, providing critical insights for cross-scale parameter optimization in microchannel design. Full article

The escalating heat flux density and temperature in highly integrated microelectronic devices adversely affect their reliability and service life, making efficient thermal management crucial for stable operation. This study utilizes Galinstan liquid metal as the coolant to investigate the flow and heat transfer performance in microchannel heat sinks incorporating various turbulator configurations. It is revealed that for microchannels featuring expanded regions, turbulators that create highly symmetric flow fields are preferable due to improved flow distribution. The long teardrop-shaped turbulator provides the best heat transfer performance among all the investigated heat transfer enhancement structures. And this turbulator yields a 13.8–25.9% higher enhancement effectiveness compared to other configurations, at the expense of a 28–41% increase in pressure loss. However, the sudden cross-sectional expansion in the expanded region causes a significant reduction in fluid velocity. Consequently, microchannels with expanded regions and turbulators exhibit a higher bottom surface temperature than the original, straight microchannels, leading to an overall deterioration in heat transfer performance. Full article

Acoustofluidic devices use Surface Acoustic Waves (SAWs) to handle small fluid volumes and manipulate nanoparticles and biological cells with high precision. However, SAWs can cause significant heat generation and temperature rises in acoustofluidic systems, posing a critical challenge for biological and other applications. In this work, we studied temperature distribution in a Standing Surface Acoustic Wave (SSAW)-based PDMS microfluidic device both experimentally and numerically. We investigated the relative contribution of Joule and acoustic dissipation heat sources. We investigated the acoustofluidic device in two heat dissipation configurations—with and without the heat sink—and demonstrated that, without the heat sink the temperatures inside the microchannel increased by 43 °C at 15 V. Adding the metallic heat sink significantly reduced the temperature rise to only 3 °C or less at lower voltages. This approach enabled the effective manipulation and alignment of nanoparticles at applied voltages up to 15 V while maintaining low temperatures, which is crucial for temperature-sensitive biological applications. Our findings provide new insights for understanding the heat generation mechanisms and temperature distribution in acoustofluidic devices and offer a straightforward strategy for the thermal management of devices. Full article

Integrated circuits have become indispensable in modern society owing to their formidable computational power and high integration, finding extensive applications in critical fields such as artificial intelligence and new energy vehicles. However, continued increases in integration density and reductions in physical size lead to a significantly higher heat flux density, thereby posing major challenges for thermal management and overall chip reliability. To address these thermal challenges, this study introduces an optimized manifold microchannel design. A three-dimensional conjugate heat transfer model was developed, and computational fluid dynamics simulations were performed to analyze the thermal–hydraulic performance. To mitigate temperature non-uniformity, several strategies were implemented: adjusting channel widths, employing uneven inlet gaps, and incorporating micro-fins. Results demonstrate that the optimized configuration achieves a maximum temperature reduction of 7.7 K, with peak thermal stress decreasing from 55.29 MPa to 47 MPa, effectively improving temperature uniformity. This study confirms that the proposed optimized design significantly enhances overall thermal performance, thereby offering a reliable and effective strategy for advanced chip thermal management. Full article

This study addresses the characterization of two-phase flow phenomena in a microchannel heat sink designed to cool high-concentration photovoltaic cells. Two-phase flows can introduce instabilities that affect heat exchange efficiency, a challenge intensified by the small dimensions of microchannels. A single polydimethylsiloxane (PDMS) microchannel was fixed on a stainless steel sheet, heated by the Joule effect, which was cooled by the working fluid HFE 7100 as it undergoes phase change. Experiments were performed using two microchannel widths with a fixed height and length, testing two heat fluxes and three values of the Reynolds number, within the laminar flow regime. Temperature and pressure drop data were collected alongside high-speed and time- and space-resolved thermal images, enabling the observation of flow boiling patterns and the identification of instabilities. Enhanced surfaces with microcavities depict a positive effect of a regular pattern of microcavities on the surface, increasing the heat transfer coefficient by 34–279% and promoting a more stable flow with decreased pressure losses. Full article

The critical heat flux (CHF) of minichannel heat sinks is crucial, as it helps prevent thermal safety incidents and equipment failure. However, the underlying mechanisms of CHF in minichannels remain poorly understood, and existing CHF prediction models require further refinement. This study systematically investigates the characteristics and influencing factors of critical heat flux (CHF) in rectangular minichannels through combined experimental and theoretical approaches. Experiments were conducted using microchannels with hydraulic diameters ranging from 0.5 to 2.0 mm, with ethanol employed as the working fluid. Key parameters-including mass flux, channel geometry, system pressure, and inlet subcooling-were analyzed to assess their influence on CHF. Results indicate that CHF increases with mass flux; however, the increase rate diminishes under higher mass flux. Larger channel dimensions significantly enhance CHF by delaying liquid film dryout. System pressure further improves CHF by reducing bubble detachment frequency and promoting flow stability. Increased inlet subcooling enhances CHF by delaying the onset of nucleate boiling and improving convective heat transfer. Four classical CHF prediction models were evaluated, revealing significant overprediction-up to 148.69% mean absolute error (MAE)-particularly for channels with hydraulic diameters below 1.0 mm. An ANN deep learning model was developed, achieving a reduced MAE of 8.93%, with 93% of predictions falling within ±15% error. This study offers valuable insights and a robust predictive model for optimizing microchannel heat sink performance in high heat flux applications. Full article

Due to its high heat transfer property, microchannel heat sink has been widely applied in thermal management, microelectronic cooling and energy conversion. To develop a microchannel heat sink featuring low pressure drop ΔP and a high heat transfer property, a V-shaped wavy microchannel (VWM) is designed and CFD simulation is carried out. Subsequently, the influences of wave amplitude A, wave length λ and inlet velocity u on the Nusselt number Nu_ave, the Dean Vortexes and ΔP are studied. Furthermore, based on the performance evaluation criteria (PEC), the optimal parameters of A, λ and u are chosen. Next, the influence of microchannel number N is studied at the same pump power. Eventually, the optimal VWM heat sink is compared with the V-shaped straight microchannel (VSM) heat sink and the rectangular-shaped straight microchannel (RSM) heat sink. The results show that many Dean Vortexes periodically emerge in the V-shaped wavy microchannel, particularly at the wave peak and valley. These Dean Vortexes are capable of thinning the thermal boundary layer, which significantly strengthens heat transfer. As A and u increase while λ decreases, the area, number and severity of the Dean Vortexes increase, and thus both Nu_ave and ΔP also increase. In the present study, the PEC first increases and then decreases, reaching its maximum value when A = 0.3 mm, λ = 5 m and u = 1.0 m/s. At the same pump power, both the heat transfer area and the total Dean Vortex number increase with the increase in N, leading to a decrease in the thermal resistance R and the maximum temperature T_max. Compared to the VSM and RSM heat sinks, the optimal VWM heat sink decreases T_max by 29.93 K and 38.03 K, decreases R by 50.46% and 56.68%, increases h_ave by 156.42% and 155.43% and increases PEC by 137% and 130.78%, respectively. Full article

To suppress the thermal stress in high-power semiconductor laser array packaging, the classic asymmetric heat dissipation structure of the array packaging was transformed into a symmetric one by incorporating microchannel heat sinks. This effectively reduced the maximum temperature, maximum thermal stress, thermal resistance, and maximum vertical displacement of the semiconductor laser array. Using the response surface methodology, mathematical models were established to correlate the maximum temperature, maximum thermal stress, and maximum vertical displacement of the semiconductor laser array with the radius, height, and spacing of circular micro-pin fins. A genetic algorithm was then employed to perform multi-objective optimization of these parameters. The results demonstrate that, compared to the original packaging configuration, the optimized semiconductor laser array exhibits a maximum temperature reduction of 16.56 °C, a maximum thermal stress decrease of 24.01 MPa, and a reduction in the maximum vertical displacement of the chip by 0.77 μm. Full article

Over the last several years, a significant advancement in high-voltage electronic packaging techniques has paved the way for next-generation power electronics. However, controlling the thermal properties of these new packaging solutions is still a major challenge. The utilization of wide bandgap semiconductors such as SiC and GaN offers effective methods to minimize thermal inefficiencies caused by conduction losses through high-frequency switching topologies. Nevertheless, the need for high voltage in electrical systems continues to pose significant barriers, as heat generation remains one of the most significant obstacles to widespread implementation. The trend of electronics design miniaturization has driven the development of high-performance cooling concepts to address the needs of high-power-density systems. As a result, the design of effective cooling systems has emerged as a crucial aspect for successful implementation, requiring seamless integration with electronic packaging to achieve optimal performance. This review article explores various thermal management approaches demonstrated in electronic systems. This paper aims to provide a comprehensive overview of heat transfer enhancement techniques employed in electronics thermal management, focusing on core concepts. The review categorizes these techniques into concepts based on fin design, microchannel cooling, jet impingement, phase change materials, nanofluids, and hybrid designs. Recent advancements in high-power density devices, alongside innovative cooling systems such as phase change materials and nanofluids, demonstrate potential for enhanced heat dissipation in power electronics. Improved designs in finned heat sinks, microchannel cooling, and jet impingement techniques have enabled more efficient thermal management in high-density power electronics. By fixing key insights into one reference, this review serves as a valuable resource for researchers and engineers navigating the complex landscape of high-performance cooling for modern electronic systems. Full article

As the demand for efficient heat dissipation in information devices continues to escalate, the heat flux of integrated packaging devices is poised to reach 100 W/cm² universally, rendering microchannel liquid cooling technology a pivotal solution in thermal management. In this work, the microchannel heat sink with spoiler cavities, optimized via field synergy principle, was integrated into the high-power electronics, and its flow and heat transfer performance were experimentally investigated using Al₂O₃-water nanofluid. The results show that the experimental and simulation results of the optimized microchannel heat sink integrated with IGBT devices are in good agreement. With structural optimization combined with an appropriate volume fraction of nanofluid, the microchannel heat sink exhibited significantly better heat dissipation performance than that of rectangular heat sinks under a heat flux of 100 W/cm². Furthermore, when the volumetric flow rate exceeded 0.6 mL/s, the heat transfer performance was improved by 38% compared to the rectangular microchannel heat sink with 1% volume fraction of Al₂O₃-water nanofluid. Full article