High Heat Flux Electronics Research Articles

Hybrid artificial neural networks-based approaches predicting the heat transfer and flow characteristics of manifold microchannels

Aiming at meeting the requirement of high heat flux electronics cooling, the geometric complexity of manifold microchannels as an energy-saving technique has been increasing rapidly. It is well worth exploring optimal prediction models for the heat transfer and flow characteristics of manifold microchannels to reduce computing resources and time costs in the optimization process. In this paper, hybrid prediction approaches based on artificial neural networks are proposed for manifold microchannels. Four optimization algorithms, namely, genetic algorithm, particle swarm optimization algorithm, artificial hummingbird algorithm, and zebra optimization algorithm were adopted to enhance the prediction performance. Initially, all prediction models were trained and tested by a numerical database including six input parameters, and the thermal resistance and pumping power were taken as the target outputs. Compared to the original method, hybrid prediction models show higher accuracy and reliability on the numerical data with regression coefficients beyond 0.987. The prediction model optimized by the artificial hummingbird algorithm shows the best performance with the mean average error for thermal resistance and pumping power decreased by 88.7% and 81.4% respectively. Additionally, the runtime of all prediction models is compared and the model optimized by the zebra optimization algorithm takes the longest time, but is still two orders of magnitude shorter than that of the traditional simulation method. Finally, the generalizability of all prediction models is further validated by a database amassed from six experimental studies on manifold microchannels. The results showed that three hybrid models can provide accurate outputs with regression coefficients beyond 0.84 which differs from the poor prediction of the original method. The model optimized by the zebra optimization algorithm shows superior prediction performance for six individual studies, two fluids, three fin shapes, and wide flow rate conditions. The trained hybrid prediction models in this study perform higher accuracy and can be cost-effective and reliable prediction tools for the rapid optimization process of various manifold microchannel applications.

Machine learning-based thermal performance study of microchannel heat sink under non-uniform heat load conditions

The parallel microchannel heat sink stands as a pivotal solution in managing high heat flux electronics due to its efficient heat transfer characteristics and ease of manufacturing. While numerous studies have explored the thermal performance and flow characteristics of microchannel heat sinks, most have focused on uniform heat loads or relied heavily on numerical methods. This study presents an experimental system tailored to generate data for analyzing the thermal performance of microchannel heat sinks under various conditions. Leveraging this dataset, four distinct machine learning models Artificial Neural Network (ANN), XGBoost, LightGBM, and K-nearest neighbor (KNN) were trained using 22 input features, totalling 560 data points categorised into geometry parameters, heating patterns, and boundary conditions details. The models were tasked with predicting six response variables: the average base temperature of the heat sink, temperature change (ΔT), hotspot temperature, heat transfer coefficient (h), Nusselt number (Nu), and thermal resistance (Rth). Among the four machine learning models, XGBoost exhibited a good predictive accuracy of an average R2 value of 0.98 and MAE values of 2.1 across all responses. Furthermore, the study delved into the impact of varying input features on prediction accuracy, revealing a consistent enhancement in accuracy with the inclusion of more features across all models.

Smart fin with automatic evaporation and regeneration for thermal management of high heat flux electronics

The high temperature of modern electronic devices poses great challenges to the safety and reliability of applications. Reasonable and effective control of device operating temperature for enhancing device performance and promoting the development of the electronics industry has a positive effect. Here, an innovative and efficient passive cooling technology is proposed to reduce the device temperature using polymerized metal fin and smart hydrogel to form smart fin. The smart fin carries away the waste heat generated by the device through evaporation and regeneration is accomplished by capturing water molecules from the environment. The smart fin is demonstrated to low down the temperature of a heater with heat flux of 2900 W/m2 by 48.3 °C and restores to its initial state after 160 min. At a threshold temperature of 60 °C, it promoted the maximum usage power by 49.4%. The evaporation and regeneration capacity of the smart fin can be controlled by ambient temperature, relative humidity, and smart hydrogel thickness. Specifically, high temperatures promote water evaporation and absorption, high humidity suppresses evaporation but favors absorption, and excessive thickness impedes water transport. This thermal management strategy with simple structure, low-cost, and easy-preparation is expected to become a universal technology in the electronics industry.

Topologically optimized manifold microchannel heat sink with extreme cooling performance for high heat flux cooling of electronics

The manifold microchannel heat sink (MMCHS) has become one of the most promising cooling solutions for high heat flux electronics due to its lower pressure drop and higher temperature uniformity compared to the traditional microchannel heat sink (MCHS). However, the microchannel configurations in previous MMCHS are dominated by parallel, straight microchannels, which would limit their further enhancement in cooling performance. In this work, we designed the microchannel configuration in the MMCHS using a topology optimization method and proposed a manifold microchannel heat sink with a topologically optimized microchannel substrate (MMCHS-TOMS). The thermohydraulic performance of the MMCHS-TOMS was experimentally and numerically studied. The results showed that the microchannel configuration with optimal cooling performance is achieved at a width ratio of inlet to outlet (Win/Wout) = 0.5 and inlet pressure (Pin) = 10 Pa. The MMCHS-TOMS demonstrates a uniform flow distribution in adjacent arrays, and the discrepancies of volumetric flow rate (V̇d) among all inlets are less than 6 %. The MMCHS-TOMS is capable of removing 1570 W/cm2 heat flux under a footprint area of 42 × 10.5 mm2 with a pressure drop of 11.9 kPa, in which the volumetric flow rate and inlet temperature are 3 L/min and 293 K, respectively. With a volumetric flow rate of 1 L/min and a heat flux of 687 W/cm2, the MMCHS-TOMS achieved a maximum cooling coefficient of performance (COP) of 78273, which is the highest value reported up to date. Moreover, oscillations in temperature (mild) and pressure drop (large) are observed in the MMCHS-TOMS when violent boiling occurs; the system stability caused by those oscillations can be suppressed via increasing the volumetric flow rate, although the COP would thus be reduced.

Numerical simulation of thermal performance of cold plates for high heat flux electronics cooling

High heat flow density electronic components need cooling plates with strong heat exchange capacity to maintain temperature balance. To obtain better cooling performance, four different flow channel types of cooling plates are designed, including an S-type channel, Z-type channel, mosaic channel and double-layer channel. The maximum temperature of the cooling plate, outlet temperature and pressure drop under different working conditions and coolant are analyzed by numerical simulation. The simulation results show that the double-layer channel design can effectively enhance the heat transfer effect of the cooling plate and reduce the pressure drop. The maximum temperature of the cooling plate of the double-layer flow channel is 6.88 ?C lower than that of the Z-type flow channel. Moreover, increasing the inlet flow rate and lowering the coolant inlet temperature can improve the cooling performance of the cold plate, but increasing the inlet flow rate will lead to an increase in the pressure loss of the cold plate. When the coolant of the dou?ble-layer channel cooling plate is 20% ethylene glycol-water solution, the cooling performance is better than the other three coolants. Other channel cooling plates perform better with water as the coolant.

Optimal parameter design of a slot jet impingement/microchannel heat sink base on multi-objective optimization algorithm

Jet impingement and microchannel cooling as effective cooling methods have been widely employed for thermal management of high heat flux electronics. In this work, a novel hybrid slot jet impingement/microchannel heat sink, combining the advantages of two cooling technologies, was proposed to achieve vertical flushing of the jet and timely discharge of the waste fluid. To further enhance the cooling performance, a 3-D numerical simulation was applied to evaluate the impact of inlet and outlet branch passage inclination ratios (Hin,1/Hin,2 and Hout,1/Hout,2), channel unit width (W1), channel width ratio (φ) and channel height (H3) on heat sink thermal-hydraulic characteristics. According to the parametric analysis, the variations in the inlet and outlet branch passage inclination ratios have significant effect on the mass flow distribution among the heat transfer channels. Afterward, to acquire the optimal compromise solution for practical applications, the artificial neural network training and multi-objective optimization algorithms, i.e. multi-objective particle swarm optimization (MOPSO) and multi-objective genetic algorithm (MOGA), are utilized to optimize the geometrical parameters, i.e. W1, φ and H3. During the optimization, the average heated surface temperature (T¯heat) and the total pressure drop (ΔP) are two conflicting objectives to evaluate the heat transfer and resistance characteristics. Finally, an optimal compromise solution (W1=1.03mm, φ=0.58 and H3=2.44mm) is chosen from the Pareto front by using the classical decision-making algorithm, i.e. TOPSIS. Compared with one objective minimization in the Pareto front, the optimal compromise solution has a sound balance between heat transfer and resistance performance. Additionally, for the optimal compromise solution, with an inlet velocity of 1.5 m/s and a heat flux of 200 W/cm2, the maximum and average temperature of the heated surface does not exceed 73 °C and 67 °C, respectively, and the total pressure drop is only 5.7 kPa.

Thermal performance of an ammonia loop heat pipe using a rectangular evaporator with liquid-guiding channels

In order to enhance the heat transfer capacity of a stainless steel-ammonia loop heat pipe using a rectangular evaporator, liquid-guiding channels were adopted to significantly reduce the liquid flow resistacne in the evaporator wick. An experimental system was established, and extensive experimental studies have been implemented to investigate its startup characteristics, heat transfer capability and thermal resistance. To be specific, the effects of heat load, evaporator attitude and antigravity on the startup performance were evaluated. According to the experimental results, the loop heat pipe showed excellent startup performance, which could realize the startup at small heat loads for different attitudes of the evaporator. Both adverse evaporator attitude and anti-gravity can cause an increase of the operating temperature of the loop heat pipe, due to poor cooling effect of return liquid and increased heat leak from the evaporator respectively. The loop heat pipe could achieve a heat transfer capability up to 300 W, corresponding to a heat flux of 20 W/cm2. The minimum system thermal resistance reached as low as 0.048 K/W at the head load of 140 W. The present study contributes greatly to the future loop heat pipe applications in high heat flux electronics cooling.

Numerical study of a liquid cooling device based on dual synthetic jets actuator

This study focuses on an efficient and innovative cooling technology to improve thermal performance of high heat flux electronics. This paper proposes a novel liquid cooling active heat dissipation device based on a dual synthetic jets actuator (DSJA). The heat transfer mechanism and flow mechanism of DSJA in the channel are studied through 3D CFD numerical simulation. Then the influence of inlet flow rate, jet orifice diameter, and diaphragm frequency on the cooling device are analyzed. Heat transfer and pressure drop are significantly influenced by the inlet flow rate when DSJA is off. DSJA has an excellent cooling capacity in the inlet flow range of 0.6–6 L/min after DSJ is on. The actuator with a water inlet turned on shows better heat transfer than the actuator without a water inlet. Increasing the diaphragm frequency from 15 Hz to 80 Hz enhances the heat transfer slightly and has little effect on pressure drop. The hydraulic thermal performance of DSJ before and after opening is 1.263, which verifies the high efficiency of DSJA for liquid cooling.

Enhancing Jet Array Heat Transfer: Review of Geometric Features of Nozzle and Target Plates

Adequate cooling of electronic components and packages is an ever-increasing challenge as devices become more powerful, compact, and portable. Highly integrated and high-performance solutions are sought across a wide range of industrial and commercial sectors, requiring new methods and means of cooling beyond the traditional fan-fin heat sink. Impinging jets, when arranged in arrays, can achieve very high local and surface-averaged heat transfer coefficients whilst providing sufficient surface area coverage for a broad range of electronic devices. As such, they are a high-potential candidate for next generation heat exchangers for cooling high heat flux electronics. This review article focusses primarily on the means by which the heat transfer of impinging jet arrays can be enhanced by straight-forward alterations of the geometric features of the jet orifices, nozzle plate, and impingement surface, as compared with the baseline case of round jets impinging on flat surfaces. From non-circular jets, to patterned micro-roughness, the review aims to collate and synthesize the state-of-the-art, highlighting advantages and pitfalls, to aid thermal engineers in designing high performance jet impingement heat exchangers.

Pool Boiling Heat Transfer on a Micro‐Structured Copper Oxide Surface with Varying Wettability

AbstractCopper surface is modified to copper oxide surface for high heat flux electronics applications. Copper oxide surface is prepared by chemical etching using NaOH and (NH4)2S2O8. A pool boiling experiment is conducted to investigate the critical heat flux (CHF) and boiling heat transfer coefficient (BHTC). The results indicate that BHTC of all copper oxide surfaces are enhanced remarkably. Bubble dynamics are also analyzed by means of a high‐speed camera. Bubble visualization demonstrates that the active nucleation sites for the copper oxide surfaces are higher than the bare copper surface.

High heat flux flow boiling of R1234yf, R1234ze(E) and R134a in high aspect ratio microchannels

Flow boiling of refrigerants in narrow channels has a great potential to cope with future challenges in the thermal management of high heat flux electronics. This study investigated the flow boiling heat transfer of R1234yf, R1234ze(E), and R134a in multi-microchannels as the applied heat flux was varied from boiling incipience to the critical heat flux. A parametric analysis on the two-phase local heat transfer coefficients was conducted for channel mass fluxes from 415 kg/m2s to 1153 kg/m2s and saturation temperatures of 30.5 ∘C and 40.5 ∘C. The test section comprised 17 channels with inlet restrictions. The channels were 298 µm wide, 1176 µm deep and 10 mm long. Three boiling regimes (I, II, III) were identified according to the observed effect of the heat and mass flux. In boiling regime I, the two-phase local heat transfer coefficient was independent of the mass flux and increased with the heat flux. In boiling regime II, the flow departed from this behavior, and a significant effect of the mass flux appeared. Finally, in boiling regime III, the two-phase local heat transfer coefficient decreased steeply with the heat flux. Flow visualization showed that a predominantly bubbly flow was present in the channels during boiling regime I. In boiling regime II, churn flow was the predominant flow regime, but appeared with more frequent vapor slugs as the heat flux was increased, eventually leading to alternating churn and wispy-annular flow. In boiling regime III, the flow regime alternated between churn and wispy-annular, with a dryout incipience leading to the progressive decrease of the two-phase local heat transfer coefficient until the achievement of the critical heat flux. The experimental data for boiling regimes I and II, amounting to 2504 local values, were compared against the prediction of selected literature correlations.

Multi-objective optimization of 3D printed liquid cooled heat sink with guide vanes for targeting hotspots in high heat flux electronics

The data center industry is currently faced with surging energy demands and a growing carbon footprint. Beside these, the industry is also faced with increasing chip power densities and thermal stresses, which can be attributed to the integration of multiple cores into a single chip. This paper presents a novel hot spot targeted cooling approach, the goal of which is to reduce both the cooling device's thermal resistance and chip thermal stresses while also lowering the pressure drop and pumping power required to cool the chip. The approach allows for the temperature of the liquid leaving the chip to be maximized, which can enable different heat recovery potentials. Multiple techniques were used to improve the heat sink's thermohydraulic performance, including a direct chip-attached heat sink, distributed water jet impingement inlets, and embedded guide vanes. A multi-objective optimization study was conducted to minimize the chip's temperature non-uniformity, thermal resistance, and pumping power. For optimization, a Bayesian-based learning technique was coupled with a genetic algorithm, which was then employed. The results show that the optimal design was comprised of variable fin density and profile in the hot spot and background regions of the chip. The optimized design showed a benchmark thermal resistance of 0.036 °C/W and a chip non-uniformity index as low as 0.81 °C. It outperforms the other hot spot targeted heat sinks that have been presented in previous literature, meanwhile also consuming relatively low pumping power.

Flow thermohydraulic characterization of hierarchical-manifold microchannel heat sink with uniform flow distribution

• Flow uniformity of manifold microchannel (MMC) heat sink is analyzed. • Flow difference between adjacent microchannels is less than 7% in hierarchical-MMC. • Pressure drop of hierarchical-MMC is reduced by 28–32% compared to typical-MMC. • Heat dissipation of 450 W/cm 2 is achieved under heated area of 9 cm 2 in experiment. • Maximum value of cooling coefficient of performance (COP) is obtained to be 19,480. The manifold microchannel (MMC) heat sink has been used for thermal management of high heat flux electronics. Flow maldistribution among microchannels is one of the major hindrances that affect the proper functioning of the typical-MMC ( i.e. , a coplanar design of the manifolds and the inlet/outlet ports) cooling system, which is attributed to the Z-shaped flow of fluid between the microchannels and the manifolds. Herein, a novel hierarchical-MMC heat sink with stacked configuration is proposed, which mitigates flow maldistribution by optimizing the flow path. First, the fluid flow and heat transfer characteristics of the typical-MMC and the hierarchical-MMC are compared through single-phase conjugate simulation. Next, experimental tests are performed on the hierarchical-MMC heat sink fabricated by Selective Laser Melting (SLM) technology under single-phase and subcooled flow boiling conditions. The numerical results indicated that the hierarchical-MMC exhibits a uniform flow distribution, and the difference of percentage of volumetric flow rate in the section plane of the parallel microchannels is less than 5%. Compared with the typical-MMC, the total pressure drop and overall thermal resistance of the hierarchical-MMC are reduced by 28–32% and 7–13% at the volumetric flow rate of 0.12–1.17 L/min, respectively. Moreover, the experimental results verified the accuracy of the numerical simulation and the feasibility of fabricating the hierarchical-MMC through SLM technology. Under subcooled flow boiling condition, a heat dissipation of 450 W/cm 2 is achieved under a footprint area of 30 × 30 mm at the volumetric flow rate of 1 L/min. The maximum value of cooling coefficient of performance (COP) for hierarchical-MMC heat sink is obtained to be 19,480 at the volumetric flow rate of 0.6 L/min and heat flux of 260 W/cm 2 .

Experimental study of nucleate pool boiling heat transfer on microporous structured by chemical etching method

Cooling of high heat flux devices and electronics devices with a high heat dissipation system uses Boiling Heat Transfer (BHT). In this paper, a pool boiling heat transfer experiments conducted on saturated distilled water for a bare and microstructured copper surface prepared through chemical etching at atmospheric pressure. A two-step chemical etching process is used for the fabrication of copper microstructure. In the first step, HNO3 and CTAB are used, and in the second step, NaOH and (NH4)2S2O8 are used. This practice comes up with simple management of various surface properties that influence critical heat flux (CHF) and boiling heat transfer coefficient (BHTC) like porosity, roughness, contact angle, etc. These properties are examined with the help of required equipment and are found better. The result of the experiment shows a significant enhancement for BHTC. The maximum BHTC is 82.7 kW/m2K, which is a 60 % increment compared to the bare copper surface. The enhancement of BHTC is due to the microstructure formed on the copper surface through chemical etching. Because of this microstructure, surface properties like roughness, surface wettability are improved in favor of boiling heat transfer performance. But due to the hydrophobic nature, chemically etched surfaces show less CHF than the bare copper surface. For repeatability performance, the surfaces' heat transfer coefficient shows a 4.8 % deviation after a four times repeated test.

Thermohydraulic performance improvement and entropy generation characteristics of a microchannel heat sink cooled with new hybrid nanofluids containing ternary/binary hybrid nanocomposites

AbstractRecently, the combination of hybrid nanofluids with microchannel heat sinks (MCHSs) has led to superior heat removal from high heat flux electronics chips. The present work aimed to evaluate numerically the first and second law performances of MCHSs using the new cost‐effective binary/ternary hybrid nanofluids. Water‐based binary and ternary hybrid nanofluids include the MgO/TiO2 nanocomposite and the CuO/MgO/TiO2 nanocomposite, respectively. The effects of the hybrid nanofluid volume concentration (vol.%) and Reynolds number (Re) on the heat transfer, pressure drop, combined thermohydraulic characteristics, and entropy generation characteristics of the MCHSs are discussed. The results show that higher values of the convective heat transfer coefficient, pressure drop, and frictional entropy generation rate are obtained when using hybrid nanofluids with high Re and vol.% values. Furthermore, by increasing the Re and vol.% values of the hybrid nanofluids, the bottom wall temperature, total thermal resistance, and thermal entropy generation rate decreased, and an increased temperature uniformity was obtained on the bottom surface of the MCHSs. In conclusion, the applied hybrid nanofluids are considered to be more promising heat transfer fluids when compared with conventional fluids such as water. Particularly, the CuO/MgO/TiO2‐water ternary hybrid nanofluid exhibited a better heat transfer efficiency than did the MgO/TiO2‐water binary hybrid nanofluid.

Membrane-Based Two Phase Heat Sinks for High Heat Flux Electronics and Lasers

Thermal management is the current bottleneck in advancement of high-power integrated circuits (ICs), and phase change heat sinks are a promising solution. With a unique structural configuration consisting of a membrane positioned above the heater surface, membrane-based heat sinks (MHSs) have thus far attained heat fluxes of up to 2 kW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and heat transfer coefficient (HTC) of up to 1.8 MW/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}~\cdot $ </tex-math></inline-formula> K using water as the working fluid. This work reports the latest progress and performance evaluation of MHS for high flux thermal management. MHS is implemented in conjunction with a low surface tension liquid to rapidly expel bubbles from the heated surface and reach a critical heat flux (CHF) of 340 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a HTC of 120 kW/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}~\cdot $ </tex-math></inline-formula> K. A parametric comparison shows that thermal efficiency, defined as the ratio of cooling capacity and pumping power consumption, of the prototypical devices exceeds values reported hitherto in literature by more than two orders of magnitude. Our results indicate that coupled with the surfaces of higher thermal conductivity and membranes of higher permeability, the MHS devices could be a promising solution to thermal management needs of high-power electronics and lasers.

Two-Phase Flow Regimes and Heat Transfer Coefficients With R245fa in Manifolded-Microgap Channels

Manifold microchannels have shown high performance in embedded two-phase cooling of high heat flux electronics, demonstrating several examples of heat dissipation of 1 kW from 1-cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chips, with low pumping power requirements. The heat transfer coefficients (HTCs) in previous studies of chip-scale manifold-microchannel coolers exhibited a peak at relatively low quality (about 0.2–0.4) and steeply declined thereafter with increasing quality. However, manifold microchannels—arrays of manifolded-microgap channels—are a more complex geometry than traditional, straight, and circular channels and therefore generate more complex two-phase flow phenomena, which influences the resulting heat transfer performance. To better characterize the flow and heat transfer in such channels, in this study, the fluid flow and wall heat transfer in a visualization test section was imaged with a high-speed optical camera and thermography. R245fa served as the working fluid due to its low-pressure operation (approximately 1.8 atm at 30 °C) and excellent thermal properties, including high latent heat, high specific heat, and high thermal conductivity. The results are reported in terms of the channel outlet flow regime and HTCs under varying heat fluxes and mass fluxes with two manifold designs. The flow regimes and HTCs are compared with well-regarded predictive relations developed for more traditional channel geometries. The emergence of intermittent, and then persistent, dryout was associated with intermittent rivulet flow at the channel outlet and was observed to cause declining average wall HTCs, even while high HTCs occurred at the consistently wetted inlet region.

Experimental and numerical study on the temperature uniformity of a variable density alternating obliquely truncated microchannel

Microchannels with liquid coolants have shown great potential in the high heat flux electronics cooling due to their enhanced heat dissipation capacity. The excessive temperature gradient along the streamwise induces significant thermal mismatch stresses and eventually leads to thermal-mechanical reliability problems in long time service. In this research, a novel variable density alternating obliquely truncated microchannel combined with oblique fin enhancement is proposed to improve the temperature uniformity. The laminar convective heat transfer and flow characteristics for different geometrical configurations are systematically investigated using experimental and numerical analysis. The analysis shows that the enhanced design AOTF-MC increases by up to 63.23% and 111.59% for the Nusselt number and decreases by up to 40.20% and 55.16% for the standard deviation of the temperature compared with the AOT-MC and the RS-MC, respectively. The improved design is also found to have a better overall thermal performance with less pressure drop penalty with a performance evaluation coefficient of 1.6. Furthermore, the variable density layout of the secondary passages significantly improves the temperature uniformity. The results may provide some general design guidelines and concepts of optimization for microchannel heat sinks.

Magnetic field enhanced ionic wind for environment-friendly improvement and thermal management application

High heat flux electronics have encountered difficulties in thermal management. There are some shortcomings in traditional cooling methods. Ionic wind cooling technology based on electrohydrodynamic (EHD) has unique advantages. There are by-product hazards and speed raising limits in the reported ionic wind generators. An electromagnetic field and nanomaterials improved ionic wind cooling system is designed for environment-friendly improvement and thermal management application. The proposed cooling system is optimized experimentally to increase the ionic wind intensity and reduce ozone generation. The results indicate that adding a magnetic field changes the movement trajectory of charged particles and thus regulates the distribution of the flow field. In the macroscopic sense, the ionic wind intensity is also improved, and the greater the magnetic flux density is, the more obvious the effect is. A maximal improvement of 58.6% was obtained. The ionic wind velocity increases by 0.71 m/s due to the synergistic effect of a magnetic field. Meanwhile, the O3 concentration decreased by more than 95% using both the magnetic field and the carbon nanotubes. When the cooling system is applied to a high-power light-emitting diode (LED) chip for thermal management, the cooling effect is remarkable. The results provide an important theoretical basis for the application of EHD technology in the thermal management of electronic devices.

Design and application of a cooling device based on peltier effect coupled with electrohydrodynamics

Miniaturization has become the development trend of light-emitting diodes (LEDs), which results in a significant increase in heat flux production and operating temperature. The accumulated heat should be dissipated effectively to ensure that the chip can work properly. The conventional cooling techniques have now reached their limits in heat removal rates. A new cooling device coupled thermoelectric cooling (TEC) with corona wind cooling (CWC) was proposed and optimized experimentally based on the second law of thermodynamics and the principle of entropy generation minimization. The results indicate that a better cooling effect and a high coefficient of performance value is obtained by turning on the TEC near the heat source firstly and adjusting the CWC power at the hot side. Increasing the input power of TEC and keeping the total cooling power unchanged, another 4.7% improvement is obtained with the highest heating power of 14 W. The target temperature can be maintained at an acceptable level (＜80 °C) if the TEC and CWC are well coupled. However, the coupling effect between TEC and CWC will be worse when the input power is large. A higher output luminous flux will be obtained when the LED chip works in the constant current mode due to the good coupling between CWC and TEC. The luminescence intensity and chromaticity properties are improved significantly. The principal component analysis (PCA) also indicates excellent comprehensive performance. The results verify the feasibility of a novel cooling device coupled TEC with CWC in cooling high heat flux electronics.