Pin Fin Heat Sink Research Articles

Multi‐objective optimization of a Fibonacci phyllotaxis micro pin‐fin heat sink

AbstractThere are still significant technical challenges associated with thermal management of electronic devices such as microprocessors. To improve heat dissipation performance of integrated circuits, a new Fibonacci phyllotaxis design of circular micropin fin heat sinks has been developed. To minimize both chip temperature and pumping power, a multi‐objective optimization technique was employed. The effect of design parameters such as phyllotaxis coefficient, pin fin diameter, and pin fin height on response parameters was numerically investigated using the full factorial design of the experiment. Artificial neural network was coupled with MO‐Jaya, to arrive at a Pareto frontier of optimal compromise solutions. The optimal set of design variables were found to be a height of 300 μm, a diameter of 122.6 μm, and a phyllotaxis coefficient of 130 μm with an inlet velocity of coolant 2.263 m/s. The selected optimum design was then investigated numerically, and the outcomes were compared to those predicted by the MO‐Jaya algorithm. The final confirmed response variables were a maximum temperature of 51.6°C and a pumping power of 0.191 W. The results show that the Fibonacci phyllotaxis structure of the micro pin fin heat sink has better heat‐dissipating performance.

CFD simulation and geometric optimization of a novel baffle heat sink for power electronics cooling

The electric drivetrain of an electric vehicle typically has two fluid circuits: an oil circuit for lubrication and a water-glycol circuit for cooling. Eliminating the water-glycol circuit can result in a more compact and lighter drivetrain. However, this requires the drivetrain components to be cooled with oil as coolant, which has inferior heat transfer properties compared to water-glycol mixtures. This is particularly challenging for the power modules in the power electronics unit, which exhibit some of the highest heat fluxes in the drivetrain. This study focusses on the design and optimization of a novel type of heat sink for laminar flows with baffles to guide the flow in four different directions. This has two main advantages: the baffles act as fins and increase the heat transfer area and they introduce a swirling motion in the oil thereby disturbing the boundary layers continuously. Computational fluid dynamics simulations using Ansys Fluent are performed to evaluate the thermohydraulic performance of the heat sink. The influence of design parameters such as the height and thickness of both fins and baffles and the baffle spacing in horizontal, upward and downward direction was evaluated by simulations with several combinations of the design space, considering manufacturing constraints. The optimization of the design showed that the fin thickness, horizontal baffle spacing and baffle length should be as small as possible, while there were optimal values for fin height, upward and downward baffle spacing, streamwise baffle spacing and baffle thickness. The simulations show that the thermal resistance of the baffle heat sink can be 19% lower than that of a benchmark pin fin heat sink at equal pumping power.

Numerical investigation of thermal and hydraulic characteristics in porous pin fin heat sinks using single phase nanofluids

This study aims to numerically investigate the thermal performance of porous square pin-fin heat sinks, considering three different configurations: inline, staggered, and 45° inline. Six different nanofluids, comprising CuO, Al2O3, and TiO2 nanoparticles dispersed in water and water–ethylene glycol mixtures at two volume fractions (φ = 0.5 % and 2 %), are employed as coolants. The impact of porosity on the thermal and fluidic behavior is also examined for the CuO–Water nanofluid (φ = 2 %) at porosity values of 40 %, 50 %, and 60 %. The commercial CFD code: Ansys Fluent 2020R1 is utilized for this numerical analysis and the results are compared to relevant experimental works for validation. The effects of heat sink geometry, nanofluid type, and porosity on heat transfer performance are systematically analyzed. The results show that the 45° inline configuration of the square pin-fin heat sink exhibits superior heat transfer enhancement compared to both the inline and staggered configurations. The use of nanofluids as coolants significantly improves the thermal performance compared to conventional fluids, with CuO–Water nanofluid demonstrating the most promising results. This comprehensive analysis provides valuable insights for the design optimization of high-performance cooling systems for electronic devices.

Pool boiling performance for GaldenR HT 55 subject to smooth, pin fin, and sintered pin fin heat sink

The dielectric fluid of GaldenR HT 55 (Perfluoropolyether) is regarded as a potential candidate for two-phase immersion cooling since its boiling point at 1 atm is 55 °C which is quite suitable for electronics cooling. The fluid is of special interest since the main vender of dielectric fluid will no longer produce FGAS after 2024. However, very rare nucleate boiling performance data for HT55 were reported in the literature. The objective of this study aims to provide nucleate boiling performance data for various heat sinks applicable for nucleate boiling. The test samples include a smooth reference surface (#1), 2 pin fins (the pin diameters are 1 mm (#2) and 2 mm (#3), and 3 pin fin with various sintered coatings (powder size: 150–200 μm (#4), 200–250 μm (#5), and 250–350 μm (#6)). Heat flux spans from 80 to 600 kW/m2. HTC for small pin fin (#2) is marginally higher than that of smooth surface, and large pin fin (#3) shows about 40 % enhancement compared to smooth surface at 140 kW/m2. HTCs for sintered pin fins are much higher than those of pin fin or smooth surface with approximately 90–95 % enhancement relative to the smooth surface at low heat flux. The visual observations indicate that sample #6 yields the largest bubble departure diameter and departure frequency. Yet bubble generations are especially pronounced on top of the pin fin. The CHF of the tested surfaces are following the sequence: #5 > #6 > #4 > #3 > #2 > #1. The sample #5 contains a CHF over 600 kW/m2 which is about four times higher than that of the smooth surface.

Effect of phase change material in cross flow and jet impingement cooling techniques used in heat sink for electronics application

This article presents the results of numerical investigation on comparison between two different cooling techniques namely cross flow and jet impingement cooling techniques used in heat sinks for the electronic components. Pin fin heat sink with and without phase change material (PCM) are considered for the investigation. The main focus of this research is to reduce the peak operating temperature of electronic component and pressure drop and to increase the Nusselt number of the heat sinks. Computational fluid Dynamics (CFD) tool is used to model and investigate the heat transfer characteristics across the heat sink. It is found that the cross flow shows superior thermal characteristics compared to jet impingement method due to which the base temperatures of pin fins in cross flow is at an average temperature of 14.5° C lower than that of jet impingement. Furthermore, the use of PCM significantly reduces the operating temperature of the pin fins by an average temperature of 7.5 °C for cross flow and 6.1 °C for jet impingement flow techniques.

Experimental and numerical investigation on heat transfer analysis of square slotted pin-fin heat sinks

This paper introduces two novel designs of pin-fin heat sink (PHFS), namely the inline slotted pin-fin (ISP) and the V-shaped slotted pin-fin (VSP), to address rapid heat dissipation for one central/graphics processing unit (CPU/GPU) in a single-phase liquid cooling system. Experimental and numerical investigations are conducted to observe the effect of heat transfer for non-slotted and slotted pin-fin heat sinks under different Reynolds numbers (225-720) and heating powers (90-120 W). Parameters such as average wall temperature, Nusselt number, thermal resistance, pressure drop, and hydrothermal performance factor are evaluated. Comparative analyses show that the slotted pin-fin heat sinks exhibit higher Nusselt numbers (Nu) and lower thermal resistance (Rth) levels than that in the non-slotted pin-fin heat sinks, particularly at lower Reynolds numbers. At the Reynolds number 225 and power of 120 W, the inline and V-shaped slotted pin-fin heat sinks experience a 13.98% and 19.69% increase in Nu and a 12.65% and 15.41% reduction in Rth compared to the non-slotted one, respectively. The V-shaped slotted pin-fin heat sink achieves more than 5 ∘C reduction in the maximum wall temperature than the non-slotted one. The slotted structure reduces pressure drop losses by minimizing dead flow areas on one hand. On the other hand, the inclined slots generate vortices behind the fins, increase shear-induced mixing and thus improve the force convection cooling performance.

Multiple hot spot cooling with flow boiling of HFE-7000 in a multichannel pin fin heat sink

Electronics cooling applications require a high cooling performance due to increasing power consumption. Phase change heat transfer is a popular approach for offering high heat flux cooling. Controlling temperature distribution and mitigating boiling instabilities under high heat flux conditions present a significant challenge. While numerous studies investigated the effect of pin fins in a minichannel with single hotspots on boiling enhancement, few research studies are available for minichannels with multiple segmented hotspots. This study's primary objective is to dissipate high heat (1.4 kW) using flow boiling of a dielectric fluid, namely HFE-7000, which has lower thermophysical properties than water, to achieve a uniform temperature distribution, and to suppress boiling instabilities. The boiling performance of a pin fin multichannel heat sink with dimensions of 3 × 14 × 300 mm (H × W × L) subjected to 8 hotspots with uniform heating was investigated in this regard. Flow boiling experiments were performed over a wide range of input heat power from ∼0.1 to ∼1.4 kW with a coolant mass flux of 500 kg/m2 s in the three parallel minichannels having staggered elliptical pin fins with no tip clearance on each hotspot and distribution pins at the inlet. High-speed visualization was used to relate the heat transfer coefficient variations along the channel to flow patterns. The heat transfer performance and flow regimes at different locations were obtained and discussed. Thanks to the mixing effect of elliptical micro pin fins with optimum geometrical parameters along the heat sink, the presence of distribution pin fins at the inlet for suppressing boiling instabilities and early transition to stable annular flow, the temperature uniformity (∼2.3 °C, temperature difference between the inlet and outlet hotspots) could be achieved at the highest heat input. Heat transfer coefficient reduction upto 27 % was reported along the channel when comparing inlet (1st) and outlet (8th) hotspots.

Investigating thermal performance enhancement in perforated pin fin arrays for cooling electronic systems through integrated CFD and deep learning analysis

Pin fin heat sinks have garnered considerable attention within the realm of thermal management for high-heat-flux electronics systems. This study advances the understanding of perforated pin fin systems, offering novel insights into heat transfer enhancement. The research explores circular and square perforation geometries located at varying positions along the pin fin length, aiming to enhance heat dissipation and extend the lifespan of electronic components. A parametric analysis examines the impact of perforation quantity on thermal performance with a rigorous comparison against non-perforated pin fins. The investigation incorporates machine learning techniques, including artificial neural networks, to predict cooling system thermal efficiency. Using computational fluid dynamics simulations and Artificial Neural Network modeling, the obtained results indicate the optimal design mode is the use of 3 square holes on the pin fin, which leads to an increase in thermal efficiency by 16.63% compared to the case without pin fins. Additionally, the mean absolute error value calculated across all data extracted from the computational fluid dynamics simulation for predicting thermal efficiency was 2.25%. This low error value further demonstrates the accuracy of the simulation data and neural network model in predicting the heat transfer performance of the pin fin designs.

Experimental investigation of the thermal-hydraulic characteristics of liquid cooling heat sinks with novel pin fins

Pin-fin heat sinks (PFHSs) in single-phase liquid cooling systems possess significant potential for extracting higher levels of heat from avionics. However, there is a scarcity of investigations on PFHSs with innovative pin fin shapes. Here, petaloid I and II, pinwheel-like, and honeycombed shapes were designed, and their thermal-hydraulic characteristics were examined under inlet temperatures of 10 and 20 °C, flow rates of 400–2000 mL/min, and heat fluxes of 60–150 kW/m2. Among these PFHSs, the honeycombed shape exhibited the highest heat transfer coefficient, followed by the pinwheel-like shape; they also displayed the lowest wall temperature. However, their Nusselt numbers were lower than those of petaloid heat sink I. The Nusselt number of each heat sink exhibited a downward trend with the increasing inlet temperature and heat flux, while the friction factor remained largely unaffected. The performances were evaluated by a comprehensive factor, and the honeycombed PFHS ranked first. New correlations for the Nusselt number and friction factor of these PFHSs were developed. The mean absolute deviations were all less than 5%, with most predicted values falling within the ±5% range compared to experimental values. These novel heat sinks are crucial for enhancing the performance of airborne liquid cooling systems.

The numerical analysis in heat transfer, fluid flow, and irreversibility of a pin-fin heatsink under the ultrasonic vibration with different transducer power assignment scenarios

The hydrothermal performance and entropy generation rate in a pin–fin heatsink were numerically investigated under different vibration transducer power distribution scenarios between 11 transducers located at 3 walls of the heatsink. Two cases were investigated; Case#A and Case#B which are different in 3 transducer locations on one wall of the heatsink. The highest convection coefficient (h) in Case#A was obtained for a variable power scenario, which escalated pressure drop (ΔP) by 91.94%. However, the highest h in Case#B was obtained for the constant power scenario. In addition, h, average temperature of CPU, and thermal resistance factor in Case#A are 5.84% higher than, 0.41% lower than, and 5.34% lower than those in Case#B. The PEC factor for Case#A is higher than unity (1.31) only under the constant power scenario, while the PEC of Case#B is higher than unity under different studied scenarios. Frictional irreversibility (Ṡfr) for Case#A was obtained as 1.45–74.56% higher than that for Case#B due to the swirl flow generated by the high-power transducers and creating the huge velocity gradients in Case#A. Nevertheless, the high flow mixing in Case#A leads to reducing the temperature gradients against Case#B, thereby thermal irreversibility (Ṡth) in Case#A is almost 7.05–19.69% lower than that of Case#B.

Numerical study and optimization of thermal efficiency for a pin fin heatsink with nanofluid flow by modifying heatsink geometry

This paper presents a numerical study on the thermal efficiency of a pin fin heatsink (HEK). The working fluid used is an alumina/water nanofluid, which enters the HEK in a laminar flow regime and exits from its surroundings. This study involves varying the distance between circular pin fins, their height, and their diameter. By altering these parameters, we determine the values of thermal resistance (THR) and temperature uniformity (Teta) on the HEK, along with the heat transfer coefficient (HTC). We further optimize the obtained results using artificial intelligence techniques to minimize the THR of the HEK, maximize the HTC, and achieve the best Teta on the HEK. This numerical investigation employs a two-phase approach to model nanofluid flow within the HEK. The optimization process yields predictions with an accuracy of less than 4%. The findings reveal that increasing the height of the pin fins reduces the HTC and the heat capacity of the HEK, while simultaneously improving the Teta on the HEK. Expanding the distance between pin fins enhances the HTC, decreases the THR of the HEK, and further improves the Teta on the HEK. Similarly, augmenting the diameter of the pin fins amplifies the HTC, reduces the THR, and enhances the Teta on the HEK.

Influence of pin-perforation shape on thermohydraulic performance of circular pin-fin heat sinks under turbulent flow

The impact of pin-perforation shape on the thermohydraulic performance of circular pin–fin heat sinks (CPFHS) under turbulent flow conditions is numerically assessed using a computational fluid dynamics software. The convective heat transfer efficiency, hydraulic resistance, and thermohydraulic performance of four pin-perforation shapes: square diamond, triangle, hexagon, and circle, are evaluated under various turbulent flow conditions (Reynolds number between 24,484 to 55,088). The sizes of all pin-perforation shapes are under a constraint that the ratio of the air–solid interfacial surface area to the total volume of pin-perforated CPFHS must be the same. The results show that all pin-perforated CPFHS demonstrate a higher Nusselt number compared to unperforated CPFHS. Those with circular perforations exhibit the highest Nusselt number with up to 39% improvement compared to unperforated CPFHS, followed by those with hexagonal, triangular, and diamond perforations, respectively. The Nusselt numbers correlate with the ease of fluid flow within perforations which is expressed using the average air velocities through perforations. In terms of hydraulic resistance, all pin-perforated CPFHS exhibit a reduction in friction factor compared to unperforated CPFHS. Among these, the largest decrease in friction factor, up to 15.8%, is observed in CPFHS featuring circular perforations, followed by those with hexagonal, diamond, and triangular perforations, respectively. The friction factors are influenced by the ratio of perforation perimeter to cross-sectional area. All pin-perforated CPFHS have a thermal performance factor greater than 1, indicating an improvement in thermohydraulic performance compared to unperforated CPFHS. CPFHS with circular perforations yield the highest thermal performance factor, reaching up to 1.44, followed by hexagonal, triangular, and diamond pin configurations, in descending order. With increasing Reynolds numbers, thermal performance factors of pin-perforated CPFHS initially rise, then gradually decline, suggesting that thermohydraulic advantages due to pin–fin perforations are diminishing as the flow become more turbulent.

Evaluation of prediction and modeling performance using machine learning methods for thermal parameters of heat sinks under forced convection: The case of external validation

The capability of ML models in thermal systems is generally determined by internal validation, while this study investigates the prediction performance of ML models with external validation. ANN, XGBoost, and RF models were created with the training-test data set obtained from the results of flat, conical, and cross-cut pin fin heat sinks. Data of 33, 66, and 99 W for the training-test data set were used for training and internal validation, while data of 49.5 W for conic Model-I and 82.5 W for conic Model-II were used for external validation. The RF showed the highest performance on the test data-internal validation and the ANN on the external validation. According to the test data not used in training, the lowest MSE is 0.0270-(RF), 1.7437-(ANN), and 14.7140-(XGBoost). In RF and XGBoost, the external validation performance decreased significantly compared to the internal validation. The MSE of the models are 8.0683-ANN, 214.4047-XGBoost, and 300.6012-RF for external validation. The thermal resistance provides more realistic results than the Nusselt number for the thermal performance evaluation of heat sinks with ML methods. The ANN based on external validation may be used to predict heat sinks' thermal performance and save money, labor, and time compared to CFD simulations.

The study of heat characteristics for micro pin-fin heat sinks with different structures

Heat flux in electronic devices has increased dramatically with the development of advanced IC technology, facing the demand for effective thermal management technology. Micro pin-fin heat sink (MPFHS) has been demonstrated to be capable of improving the heat transfer capability and suppressing temperature rise effectively. In order to elaborate the discrepancy of heat dissipation of the MPFHS due to the cross-section shapes of pin-fin structures a set of heat sink samples with four different shapes, including the circle-MPFHS, the square-MPFHS, the crisscross- MPFHS, and the octagon-MPFHS, are fabricated with micromachining technology. Then, the thermal characteristics are tested by integrating the heat sinks with a Pt film resistor chip as the heating source, and nucleate boiling phenomenon was observed with a high-speed camera. Results showed that concave corners in pin-fin structures increased the specific surface area, but generated low velocity vortexes in back flow regions, reducing the heat transfer capability. The heat transfer coefficients of the octagon-MPFHS, the crisscross-MPFHS, and the circle- MPFHS was increased by 161.9 %, 152.4%, and 85.7 %, respectively, relative to the square-MPFHS at the flow rate of 147 kg/m2s. The heat transfer coefficients of the octagon-MPFHS, the crisscross-MPFHS, the circle-MPFHS, and the square- MPFHS was increased by 7.27%, 11.32%, 2.56%, and 4.76% when the mass-flow rate was increased from 147 kg/m2s to 295 kg/m2s. The nucleate boiling phenome-non in the crisscross-MPFHS showed periodicity and positive feedback effect, resulting in local dry-out and consequent heat transfer capability deterioration. This study will contribute to the design and modification of MPFHS.

Mathematical Simulation of Plat-Pin Fin Heat Sink Installed under the Solar Panels

Mathematical simulation of plat–pin fin heat sink installed under solar panels was conducted. Based on the problem of heat accumulation inside the solar panel, the electricity generation efficiency become reduced with a higher heat. Thus, the objective was to design and simulate plate and pin cooling. Two shapes of pin consisting of plate and cylindrical pin were studied. The investigated process was divided into two stages. The design and calculation of the heat sink fin was the first stage. The process of simulating solar panels with fins attached and without fins using the SOLIDWORKS program was the second stage. Three factors were considered: the direction of the panel installation (S, SE, and SW), the inclination angle () of the solar panel, and the style of installation (Transvers and longitude fins). The appropriated condition for reducing the temperature of solar panels was discussed. The results showed that the minimal temperature of the solar panel was obtained at the southeast (SE) direction with an inclination angle () of 18°. Heat dissipation was achieved by the transvers fins in which a maximum temperature reduction gave 6.39 ℃.

The effects of input power and ambient temperature on the thermal performance of conical pin fin heat sink in natural convection

In the present study, thermal performance tests of horizontally oriented HSconical, HScross-cut, and HSflat with a base plate dimensions of 80*80*5 mm3 were performed in natural convection. The effects of ambient temperature (30 and 40 °C), input power (16.5 and 33 W), and conical pin fin geometry on the thermal performance of the HSs were investigated. The thermal resistance of the heat sinks decreases while the convective heat transfer coefficient, average surface temperature, and average junction temperature increase with increasing ambient temperature and input power. However, the Nusselt number increases with increasing ambient temperature for all HSs at 16.5 W, while the Nusselt number decreases with increasing ambient temperature at 33 W. The highest convective heat transfer coefficients are 32.17, 30.68, and 19.61 W/m2K for HSconical, HSflat, and HScross-cut at 33 W and 40 °C, respectively. The lowest thermal resistances are 2.75, 2.80, and 3.81 K/W for HSconical, HScross-cut, and HSflat at 33 W and 40 °C, respectively. Thermal resistances of HSconical and HScross-cut decreased by 27.78 % and 26.44 % at maximum and 27.06 % and 24.58 at minimum, respectively, compared to HSflat. The results show that the conical fins have better thermal performance in natural convection.

Hydraulic and thermal performances of micro pin fin heat sink with increasing pin fin height

This study investigates numerically the impacts of pin fins (PF) with varying height on the pressure drop ΔP, the bottom average temperature Tbw, the Nusselt number Nu and the thermal performance factor η of a micro pin fin heat sink (MPFHS). Three groups of PF structure characterized by a different height increase mode are introduced: Case 1: structure with constant height step, Case 2: structure with increasing height step, and Case 3: structure with decreasing height step. The findings in this work show that ΔP and Nu increase but Tbw decreases with the increasing height step for Case 1 and with the increasing increment of the height step for Case 2 and Case 3. When comparing their thermal and hydraulic performances, Case 2 demonstrates the best thermal performances, whereas Case 3 has the best hydraulic performance when the total height steps of PFs in all three kinds of heat sink are kept constant. Furthermore, this study finds that the PF with increasing height can always enhance η of the MPFHS compared to PF with uniform height. This finding validates the performance advantage of the PF with increasing height and offers the potential technique for the optimization design of MPFHS.

Numerical Simulation for Cooling of Integrated Toroidal Octagonal Inductor Using Nanofluid in a Microchannel Heat Sink

This paper presents a comprehensive numerical simulation study focused on the cooling of integrated toroidal octagonal inductor using nanofluids within a microchannel heat sink. The investigation utilizes COMSOL Multiphysics 6.0 integrated with the Fluid Flow and Conjugate Heat Transfer Module. The primary objective is to explore and understand fluid flow and heat transfer characteristics within the integrated inductor. The study involves testing three distinct fluids, water, CuO-water nanofluid, and Al2O3-water nanofluid, under laminar flow conditions within microchannels. The choice of fluid plays a significant role in heat transfer, interacting with the microchannel geometry to optimize performance. Three-dimensional computational fluid dynamics (CFD) models are meticulously developed; focusing on toroidal inductors equipped with micro pin fins heat sinks. The study commences by detailing the geometry of the micro coil and the integrated heat sink. The simulation encompasses a mathematical model that captures the intricate interplay between the governing Navier-Stokes equations for fluid dynamics and the heat transfer equations within the integrated inductor. As φ increases, temperature, viscosity, and pressure decrease. CuO-water and Al2O3-water nanofluids play a significant role in influencing laminar flow and key thermal parameters in the toroidal inductor. These nanofluids, which consist of base fluids (water) with dispersed nanoparticles (CuO or Al2O3), are employed as cooling agents to enhance heat transfer. The presence of nanoparticles in the fluid alters its thermal properties, leading to changes in the flow dynamics and overall heat dissipation within the toroidal inductor.The laminar flow characteristics are affected by the nanofluid's viscosity, density, and thermal conductivity. Additionally, the Nusselt number, Reynolds number, and thermal resistance are key thermal parameters that reflect the performance of the cooling system. The nanofluid's influence on these parameters is crucial for understanding and optimizing the thermal management of the integrated toroidal inductor. The enhancement of heat dissipation in the toroidal inductor is achieved through improved thermal properties of the nanofluid. Higher nanoparticle concentrations result in better heat transfer rates, leading to lower temperatures in the toroidal inductor. This, in turn, improves the overall efficiency and performance of the cooling system. The viscosity of the nanofluid is influenced by the presence of nanoparticles. The pressure within the microchannels is also affected by the nanoparticle concentration. An increase in φ can lead to changes in pressure drop along the microchannels. Understanding these variations is crucial for designing an effective cooling system.

Numerical investigation of thermal performance enhancement of pin fin heat sink using wings with different angles

The current study represents a numerical investigation of the pin fin heat sink performance with different angles of wings. Five angles ranging from 0° to 90° have been represented and studied under inline and staggered arrangements of pin fins. Reynolds numbers range from 13,500 to 37500. The highest Nusselt number has been achieved by angle-0° with inline arrangement while it has been achieved by angle-22.5° with staggered arrangement. On the other hand, the maximum friction factor with both inline and staggered arrangements is represented by angle-0°. The highest thermohydraulic performance has been achieved by angle-22.5° for staggered arrangement while case without wings gives the highest performance for inline arrangement. Using wings in staggered arrangement shows significant effect on heat transfer performance. While it is not recommended to use wings in case of inline arrangement.

Study on spray cooling characteristics of dry ice particles for IGBT in high-speed trains{fr}Etude des caractéristiques de refroidissement par pulvérisation des particules de glace sèche pour l'igbt dans le train à grande vitesse

Aiming at the high efficiency cooling problem of IGBT(Insulated Gate Bipolar Transistor) module of traction converter for high-speed Train, a method of spray cooling with natural dry ice particles was proposed. The heat sinks with pin-fin and straight-fin structure were designed, and the heat sinks with optimum structure size selected by simulation were developed, and the heat sinks were provided with visual shells, as well as single outlet, double outlet and four outlet of the three different ways of outlet. The gas-solid two-phase flow, heat and mass transfer characteristics of dry ice particles in the heat sinks were studied by means of simulation and experiment. By comparison, it is found that the flow and heat transfer in the pin-fin heat sink have a good cooperation, and it is most suitable for the IGBT module with spray cooling of dry ice particles, which can reduce the temperature of IGBT from 70 ℃ to 55 ℃ in 75 s, compared with the fin-free heat sink, the heat transfer performance is improved by 12 %, and the double-outlet pin-fin heat sink has the best effect, the temperature difference of the heat transfer substrate is 19.8 ℃, and the average temperature of the heat transfer substrate is only 22.5 ℃ compared with that of the open type, which is 27.3 ℃ lower. Double outlet dry ice particles spray pin-fin heat sink is an efficient heat sink, thermal resistance is only 0.066 K/W, it can meet the current practical application of high-speed train cooling needs, solve the problem of heat dissipation of IGBT module for high-speed train, it lays a foundation for the development of dry ice particles spray heat sink.