Foam Heat Sink Research Articles

Investigation of the radiated emission of honeycomb structured aluminum foam/cellular heatsinks at 1–10 GHz

Metal foams or cellular structures like honeycombs, can also be evaluated according to mechanical, acoustic, thermal, and chemical resistance parameters in terms of functionality. However, it is vital to investigate the performance of these cellular structures' radiated emission (RE), which can be used as PCB heatsinks. In this study, the radiated emission (RE) performance of honeycomb-structured aluminum foam (or cellular) heatsinks (AFH), which can be considered as unidirectional regular foam, is examined in the frequency range of 1–10 GHz as a novelty. Also, the effect of four primary variables (the geometry of AFH, honeycomb hole direction, honeycomb cell size, and honeycomb cell wall thickness) on the RE performance of AFH is investigated. Unlike classical honeycomb production methods, the investment flask mold casting (loss wax) method is preferred due to the complex offset strip geometry of designed honeycombs. The original design offset hexagonal honeycomb structures were successfully produced using this investment casting method with additive manufacturing technologies from molten metal. While all simulations are carried out using CST Studio Suite, the RE performance of the proposed AFHs is measured in a standard 3 m fully anechoic chamber using a reference horn antenna and vector network analyzer (VNA). When the results are examined, the measured and simulated results agree with each other quietly. Regarding RE, structures with a CPI value of 14 are better at low frequencies, while structures with a CPI value of 3.5 are better at high frequencies. Secondly, the honeycomb cell thickness value does not significantly affect EMI performance. Lastly, although there is no significant difference in EMI in the low-frequency region, it is better to use a directional structure with vertical holes in the high-frequency region. As a result, in the design of AFH, the RE performances of the heatsinks and their thermal performance should be considered.

Computational Modelling of Heat Transfer through Aluminium Metal Foams for LiFePO4 Battery Cooling

Abstract: Temperature is crucial for battery pack durability and power. Folded fin and serpentine channel cooling methods are mostly used to cool the pack. However, fluid absorption during cooling can reduce capacity and cause downstream temperatures to be higher than upstream. Consistent cooling is vital to prevent temperature variation and increase battery pack lifespan. This work is concerned with the computational study of heat dissipation from open-cell aluminium metal foam for cooling LiFePO4 battery packs. The battery module consists of six pieces of pouch cell and three pieces of the aluminium foam heat sink. In the present study, aluminium foams are positioned between the LiFePO4 battery modules that are arranged in a vertical manner. Thermal interaction between the battery module and aluminum foam was studied. The effect of pore density on heat dissipation performance at different mass flow rates was explored. It has been discovered that aluminium foam with suitable porosity and pore density can efficiently cool the LiFePO4 battery pack. This paper provides a theoretical framework for designing a thermal management system for lithium- ion batteries using aluminium foam. Background: Metal foam cooling is an established technique for thermal management of Lithiumion batteries in electric vehicles. Objective:: The present study aims to analyze heat transfer through aluminium metal foams for vertically aligned LiFePO4 battery pack cooling. Methods: The Darcy extended Forchheimer (DEF) model examines fluid flow through metallic foams, using the local thermal non-equilibrium model to determine heat transfer. Results: The impact of the density of pores in the aluminium foam on the average wall temperature and temperature difference along the battery surface is determined. The variation of heat transfer of lithium-ion battery modules for different mass flow rates is also studied. Conclusion: The results indicate that utilizing aluminium foam as a heat transfer medium for battery modules significantly enhances their thermal management performance.

Waste heat management in electric motors using thermoelectric generator integrated with phase change material and metal foam-embedded heat sink

The waste heat management process from various thermal sources is associated with promising results in the energy conversion field. Thermoelectric generators integrated with phase change materials containing metal foams are useful means for recovering waste heat and converting it into electrical energy. Installing these hybrid cases on common heat sources and providing a practical strategy for waste heat management addresses a significant research gap in this field. The aim of this study is to manage waste heat from a three-phase asynchronous electric motor of a milling machine for the first time using a novel prototype thermoelectric system. Four thermoelectric modules (connected electrically in series) with zero-cooling energy phase change material and copper foam heat sink were embedded on the motor body. Hence, continuous and fluctuating loads were imposed on the motor, starting from ambient temperature. This caused the motor body to heat up and transfer the wasted heat to the module and the environment. The results of this study show that the proposed system was successfully started via the waste heat of the motor body. Thermal energy was absorbed from the hot side of the module, and the hybrid heat sink controlled the temperature of the cold side. Moreover, an appropriate temperature difference was provided across the module, and the system produced electricity for a long time during milling operation. The maximum output voltage in constant and periodic loads, with on/off durations of 180 s and 360 s, was recorded as 960 mV, 1280 mV, and 1440 mV, respectively. The mentioned hybrid thermoelectric system provides a unique solution for waste heat management in industrial applications, improving economic savings.

Performance improvement of building-integrated photovoltaic panels using a composite phase change material-carbon foam heat sink: An experimental study

Building-integrated photovoltaic (BIPV) panels are important for enhancing building self-power generation, promoting sustainable energy practices, and reducing dependence on the grid. Nevertheless, the efficiency and output power of these panels are negatively affected by the temperature increase caused by incident solar radiation. Thus, the present study introduces an innovative paraffin/carbon foam composite phase change material for efficient thermal management of building-integrated photovoltaic panels. Through indoor and outdoor experimental tests, the study evaluated and compared the performance of the proposed system. This system integrates a PV panel with an RT-55 phase change material and carbon foam structure (BIPV-PCM-CF) and was compared to three other cases, including a naturally cooled free PV panel, a building wall integrated PV panel to simulate conventional building-integrated photovoltaic system (BIPV), and a PV panel integrated with only RT-55 paraffin wax as the phase change material (BIPV-PCM). The study found that integrating the PV cell into building walls (BIVP) increased its temperature by 9.61 °C and decreased generated power and efficiency by 5.11 % and 10.95 %, respectively, compared to the free PV panel. On the other hand, the BIPV-PCM panel reduced module temperature by 18.1 °C but could not solidify the needed amount of PCM during the nighttime. The BIPV-PCM-CF panel, which incorporated carbon foam with PCM, outperformed the other systems, producing a cooling performance of 22.94 °C and increasing electricity generation and system efficiency by an average of 12.64 % and 27.35 %, respectively, compared to the free PV panel. These findings highlight effective strategies to promote sustainable energy practices, improve the electric performance of BIPV panels, and reduce dependence on non-renewable energy sources in buildings.

Evaluation of thermocompressed nanoporous copper deposit to replace soldering for power electronic metal foam heat sinks

Evaluation of thermocompressed nanoporous copper deposit to replace soldering for power electronic metal foam heat sinks

Pore-scale numerical investigation on comprehensive heat transfer performance of homogeneous and graded metal foam heat sinks

In order to improve the heat dissipation efficiency of heat sinks, heat sinks filled with metal foam were proposed and numerically studied in this work. Different shapes, including the tetrakaidecahedron, triangular prism, and equivalent tetrahedron, were employed to develop geometries for the cells, ligaments, and nodes of the metal foam. Computational simulation was carried out to analyze the hydraulic and thermal performance of the homogeneous metal foam(HMF)-filled heat sinks and graded metal foam (GMF)-filled heat sinks. The study found that well-designed GMF-filled heat sinks can improve both hydraulic and thermal performance. A graded pores per inch (PPI) negative change along the X-axis direction can improve the comprehensive heat transfer performance (CHTP), and the positive change has a similar effect. Graded PPI negative change along the Y-axis direction can effectively improve the CHTP, while the positive change has no effect. Moreover, a greater thickness of the metal foam with a larger PPI leads to better performance. GMF-filled heat sinks can also effectively reduce the surface temperature of the bottom plane and enhance the convection performance.

High-performance flexible thermoelectric devices with a copper foam heatsink for personal thermal management

A Bi2Te3-based thermoelectric device with high thermoelectric performance and flexibility for human body waste heat recovery and temperature management.

Analysis of Nanofluid Heat Transfer and Entropy Generation in a Novel Metal Foam Heat Sink

This study investigated the impact of key parameters, including Re (300 ≤ Re ≤ 1800), Φ (0% ≤ Φ ≤ 2.5%), ɛ (0.2 ≤ ɛ ≤ 0.9), and Da (10−4 ≤ Da ≤ 10−1), on heat transfer and entropy generation in a novel metal foam heat sink. Results show that increasing the Darcy number to 10−1 can enhance the average Nusselt number by approximately 18.05% while placing Al.Cu foam in the middle of the heat sink can significantly reduce the CPU surface temperature by up to 15 .C. Additionally, increasing the Reynolds number from 300 to 1800 can lower the thermal entropy generation by up to 51.55%. The metal foam’s effectiveness was evaluated using performance evaluation criteria (PEC).

Enhanced performance of pinned metal foam heat sinks with dielectric coolant – A pore-scale numerical study

Recent advancements in the development of microprocessors have resulted in the design of smaller microchips with improved performance. The new designs require proper cooling systems to prevent performance degradation and permanent damage to the chips. Extended surfaces, including fin, pin, or metal foam, are one of the prominent approaches in cooling systems designs. So far, there has been limited research, especially considering pore-scale analysis on the combination of pin/fin with metal foam, which is expected to offer promising cooling performance. This study aims to evaluate the performance of pinned metal foam heat sinks with dielectric coolant as a potential cooling system for microchips. A three-dimensional pore-scale numerical model is developed to analyze the performance of the proposed heat sinks. The effect of different parameters such as Reynolds number, heat flux, pore density, and different pin shapes are investigated. The results reveal that at a Reynolds number of 100, almost all the metal foam heat sinks enhance the heat transfer performance, which can be as large as 22% in some cases. Furthermore, adding pins increases the heat energy dissipation with a slight penalty of pressure drop depending on its hydrodynamic adaptation. Too dense or loose metal foam either increases the pressure drop or decreases the heat transfer rate, deviating from the optimum range. Lastly, it is revealed that heat flux from the heater does not significantly change the performance of the pinned metal foam heat sinks.

Machine learning approach to predict heat transfer and fluid flow characteristics of integrated pin fin-metal foam heat sink

Integrated pin fin-metal foam (PF-MF) heat sink offers enhanced thermal performance owing to the higher surface area and flow mixing. By realizing the strong influence of geometrical parameters of PFs, morphological properties of MF, and coolant hydrodynamics on the thermal-hydraulic performance of the PF-MF heat sink, this article presents a machine learning (ML) surrogated multiparameter and multi-objective optimization framework to determine optimal PF-MF heat sink layouts within the laminar flow regime to enhance the thermal performance of the heat sink with a minimal pumping power penalty. Four supervised regression ML models, namely random forest, extreme gradient boosting, support vector regressor, and artificial neural networks (ANN), were considered while searching for the best surrogate. Four geometrical parameters of PFs, such as PFs diameter (D), height (h), longitudinal pitch, transverse pitch, two morphological properties of MF, i.e., pore density porosity and coolant flow condition, i.e., Reynolds number have been considered as design parameters. The heat transfer and fluid flow performance of the heat sink are evaluated using nondimensional Nusselt number and friction factor A high-fidelity 3-D computational fluid dynamics/heat transfer (CFD/HT) model has been developed to evaluate the thermal-hydraulic performance of all PF-MF heat sink layouts. Furthermore, utilizing the numerical data, ML models have been trained and fine-tuned to accurately predict the overall performance of the PF-MF heat sink. Upon testing the prediction and interpolation capability of all considered ML models, ANN outperforms other models, hence, ANN model has been coupled with genetic algorithm (GA) optimizer to identify three different optimized PF-MF heat sink layouts at three different Finally, the result shows that the ANN surrogated GA-optimized PF-MF heat sink layout can improve the overall thermal-hydraulic performance by approximately 19–35% compared to the best PF-MF heat sink layout among the used input feature space for ML model.

Thermal management of the central processing unit cooling system using a cylindrical metal foam heat sink under the influence of magnetohydrodynamic nanofluid flow

PurposeEfficient thermal management of central processing unit (CPU) cooling systems is vital in the context of advancing information technology and the demand for enhanced data processing speeds. This study aims to explore the thermal performance of a CPU cooling setup using a cylindrical porous metal foam heat sink.Design/methodology/approachNanofluid flow through the metal foam is simulated using the Darcy–Brinkman–Forschheimer equation, accounting for magnetic field effects. The temperature distribution is modeled through the local thermal equilibrium equation, considering viscous dissipation. The problem’s governing partial differential equations are solved using the similarity method. The CPU’s hot surface serves as a solid wall, with nanofluid entering the heat sink as an impinging jet. Verification of the numerical results involves comparison with existing research, demonstrating strong agreement across numerical, analytical and experimental findings. Ansys Fluent® software is used to assess temperature, velocity and streamlines, yielding satisfactory results from an engineering standpoint.FindingsInvestigating critical parameters such as Darcy number (10−4 ≤ DaD ≤ 10−2), aspect ratio (0.5 ≤ H/D ≤ 1.5), Reynolds number (5 ≤ ReD,bf ≤ 3500), Eckert number (0 ≤ ECbf ≤ 0.1) , porosity (0.85 ≤ ε ≤ 0.95), Hartmann number (0 ≤ HaD,bf ≤ 300) and the volume fraction of nanofluid (0 ≤ φ ≤ 0.1) reveals their impact on fluid flow and heat sink performance. Notably, Nusselt number will reduce 45%, rise 19.2%, decrease 14.1%, and decrease 0.15% for Reynolds numbers of 600, with rising porosity from 0.85 to 0.95, Darcy numbers from 10−4 to 10−2, Eckert numbers from 0 to 0.1, and Hartman numbers from 0 to 300.Originality/valueDespite notable progress in studying thermal management in CPU cooling systems using porous media and nanofluids, there are still significant gaps in the existing literature. First, few studies have considered the Darcy–Brinkman–Forchheimer equation, which accounts for non-Darcy effects and the flow and geometric interactions between coolant and porous medium. The influence of viscous dissipation on heat transfer in this specific geometry has also been largely overlooked. Additionally, while nanofluids and impinging jets have demonstrated potential in enhancing thermal performance, their utilization within porous media remains underexplored. Furthermore, the unique thermal and structural characteristics of porous media, along with the incorporation of a magnetic field, have not been fully investigated in this particular configuration. Consequently, this study aims to address these literature gaps and introduce novel advancements in analytical modeling, non-Darcy flow, viscous dissipation, nanofluid utilization, impinging jets, porous media characteristics and the impact of a magnetic field. These contributions hold promising prospects for improving CPU cooling system thermal management and have broader implications across various applications in the field.

Performance of discretely mounted metal foam heat sinks in a channel with nanofluid

Solving the heating problem of electronic systems, whose performance and power consumption increase with the developing technology, has been the common research topic of many researchers today. In this context, conventional cooling methods should be improved by using innovative materials to achieve more effective cooling performance. In this study, metal foam heat sinks (Al-6101) with pore densities of 10 and 40 pore per inch were utilized instead of commercially finned surfaces used in electronic cooling applications, and their effects on thermal and pressure performance were investigated. The experiments were carried out under steady state conditions. As the coolants, the deionized water (base fluid) and CuO-H2O nanofluids which was prepared with different concentrations and surfactant additive, were used. The volumetric flow rates of the fluids were chosen in range of 17.6 L/h − 76.5 L/h and the heat fluxes were selected in range of 3267 W/m2 − 5400 W/m2. The effect of each parameter on heat transfer was investigated with 5 different prepared nanofluids. The following experiments were carried out by using metal foam heat sinks and the nanofluid (w/w, 0.1% CuO/2% PEI-H2O) where the best results were obtained. The obtained results were compared with the base fluid. With the use of 10 and 40 pore per inch metal foam heat sinks together with the base fluid, an improvement in the mean convection heat transfer coefficient between 11.1% and 22.2% was achieved at all heat fluxes and volumetric flow rates compared to the empty surface (surface without metal foams). When nanofluid (w/w, 0.1% CuO/2% PEI-H2O) was used together with metal foam heat sinks, an improvement changing between 26.3% and 42.5% was recorded. When the effect of all parameters used in the experiment were examined, the best results in terms of thermal performance were obtained when nanofluid with w/w, 0.1% CuO/2% PEI-H2O content and 10 pore per inch metal foam heat sinks were used together. Results suggest that the use of nanofluid together with metal foam will satisfy the economy and power consumption requirements of cooling electronic systems.

Three-dimensional transient CFD modeling of multiple finned aluminum foam heat sinks in a horizontal channel

Finned metal foam heat sinks are well-known because of their excellent performance in cooling of powered electronics. In this study, three-dimensional transient numerical simulations of finned aluminum foam heat sinks in a forced convection of air were carried out using commercial COMSOL. The geometry under consideration consists of an array of finned aluminum foam heat sinks mounted on heater blocks and placed on a plate in a horizontal channel. Heat sink aluminum foam regions were considered as porous media with a local non-equilibrium thermal model to evaluate thermal characteristics, while the Forchheimer-Brinkman extended Darcy model is considered for the flow analysis. Our main concern in the present study is to evaluate the transient thermal–hydraulic behavior and the cooling performance under constant flux heat sources while varying the Reynolds number and variable morphological parameters of the aluminum foam, i.e., porosity (ε) varied from 0.85 to 0.95. The thermal performance ratio and the average Nusselt number of the finned aluminum foam heat sinks are 23.14% and 30%, respectively, larger than the finned aluminum heat sinks. As the Reynolds number increases, the thermal characteristics are enhanced, and the pressure drop is increased. An increase in porosity causes a reduction in heat transfer rate and an elevation of pressure drop.

Thermal Management of Microelectronic Devices Using Nanofluid with Metal foam Heat Sink.

Microelectronic components are used in a variety of applications that range from processing units to smart devices. These components are prone to malfunctions at high temperatures exceeding 373 K in the form of heat dissipation. To resolve this issue, in microelectronic components, a cooling system is required. This issue can be better dealt with by using a combination of metal foam, heat sinks, and nanofluids. This study investigates the effect of using a rectangular-finned heat sink integrated with metal foam between the fins, and different water-based nanofluids as the working fluid for cooling purposes. A 3D numerical model of the metal foam with a BCC-unit cell structure is used. Various parameters are analyzed: temperature, pressure drop, overall heat transfer coefficient, Nusselt number, and flow rate. Fluid flows through the metal foam in a turbulent flow with a Reynold's number ranging from 2100 to 6500. The optimum fin height, thickness, spacing, and base thickness for the heat sink are analyzed, and for the metal foam, the material, porosity, and pore density are investigated. In addition, the volume fraction, nanoparticle material, and flow rate for the nanofluid is obtained. The results showed that the use of metal foam enhanced the thermal performance of the heat sink, and nanofluids provided better thermal management than pure water. For both cases, a higher Nusselt number, overall heat transfer coefficient, and better temperature reduction is achieved. CuO nanofluid and high-porosity low-pore-density metal foam provided the optimum results, namely a base temperature of 314 K, compared to 341 K, with a pressure drop of 130 Pa. A trade-off was achieved between the temperature reduction and pumping power, as higher concentrations of nanofluid provided better thermal management and resulted in a large pressure drop.

Mathematical/Statistical Research of Improved Metal Foam Heat Sink with Fe3O4-H2O Nanofluids

Mathematical/Statistical Research of Improved Metal Foam Heat Sink with Fe3O4-H2O Nanofluids

Influence of fin thickness variation on the thermal performance of metallic foam heat sink laminar condition

In recent years, open-pore metallic foams have been employed in a wide variety of applications owing to the essential qualities that they possess. In the present study, the thermal performance of a finned heat sink made from open-cell copper foam was investigated numerically under laminar forced conditions. The influence of fin thickness, air velocity, and heat fluxes on the average heat sink base temperature to ambient temperature difference, the Nusselt number, and pressure drop were investigated. Fin thickness was generally taken as 2, 5, 7, and 10 mm. Heat fluxes were taken from (600 to 3000) W/m2, while the air velocity was taken from 0.04 to 0.16 m/s. The findings of laminar flow indicate that straight fins with a thickness of 10 mm minimize the temperature difference between the heat sink's base and the surrounding air the most, followed by fins with thicknesses of 7 mm, 5 mm, and 2 mm. At 3000 W/m2, a change in velocity from 0.04 to 0.16 m/s increases the average base temperature difference (i.e. (Tbase-Tamb)) by 118.9% for a heat sink with 10 mm straight fins. . At a heat flow of 600W/m2, the Nusselt number grew by 72.6%, 60.7%, and 45.7% when fin thickness was raised from 2 mm to 10 mm, 2 mm to 7 mm, and 2 mm to 5 mm, respectively. The results also demonstrate that the pressure drop rises with increasing fin thickness.

Investigation of flow and heat transfer behavior of integrated pin fin-aluminum foam heat sink

• A novel aluminium foam heat sink (AFHS) consisting of pin fin inserts is proposed. • The developed mathematical model is validated with experimental data. • Thermo-hydraulic characteristics of proposed heat sinks are numerically studied. • Pin fin inserts lead to an enhancement on the heat removal capability of AFHS. • Pressure drop along the flow direction increases with pin fin insertion into AFHS. With the rapid development in the electronics industry, the thermal management of high power density electronic products (HPDEPs) has become very important and requires innovative heat removal technologies. In this study, an integrated heat sink (IHS) fabricated by combining aluminum foam and pin-finned heat sink configurations that are frequently used in the cooling of electronic products has been proposed as an effective solution for the thermal management of HPDEPs. The heat removal and pressure drop characteristics of the IHS were numerically investigated for its various design conditions such as the length/height ratio ( L/H ), fin profile, fin/foam height ratio ( H fin /H foam ), and heat sink/fin volume ratio ( V hs /V f ) over the range of Reynolds ( Re Dh ) number from 500 to 3500 by using the COMSOL Multiphysics v5.4. Before the numerical study was performed, to verify the outcomes of the developed simulation models, some of the IHS subjected to the numerical study were fabricated and their pressure drop and heat removal performances were experimentally examined in the range of Re Dh from 596 to 3551. As a result of the study, it was found that the thermal contact resistance ( TCR ) between the IHS and the heated surface has a greater effect on the Nusselt ( Nu ) number compared to the TCR between the solid fins and aluminum foam. The in-line or staggered arrangement of pin fins inside the aluminum foam did not lead to any significant difference in the overall performance of investigated IHS. For all the IHS examined, an increase in Re Dh results in a similar increase in the Nu and ΔP along the flow direction. In general, the most efficient IHS among the investigated ones in terms of the H fin /H foam ratio is the IHS with half-length fins, H fin /H foam =15/30. Average values of thermal performance factor ( ƞ) of the IHS with H fin /H foam ratio of 15/30 in in-line and staggered arrangement over the Re Dh number studied are 1.3 and 1.25 times higher relative to IHS with H fin /H foam ratio of 30/15. For a fixed number of fins, η of the IHS with fins of 4mm diameter is superior up to Re Dh =2000, after which, the situation varies in favor of the 8mm solid finned aluminum foam heat sink. Increasing the fin diameter from 4mm to 12mm in both fin configurations worsens the average value of ƞ by 10%. For a constant fin diameter, IHSs with 9 fins in in-line and 8 fins in staggered configuration have the highest ƞ when the Re Dh is greater than 2500 and 2000, respectively. Among the fin profiles examined, the IHS with elliptical fins is found to have the highest η , with a value of 1.24, at Re Dh =3500.

Experimental investigation for thermal performance enhancement of various heat sinks using Al2O3 NePCM for cooling of electronic devices

Electronic devices are being used extensively for different applications, where the thermal management of these devices is still a critical challenge due to rapid miniaturization, high heat flux and constantly rising temperature. Phase change materials (PCMs) based thermal management is adopted, but the low thermal conductivity limits their use in temperature-controlled electronic devices. Nano-enhanced phase change materials (NePCMs) can advance the heat transfer rate (HTr), decrease the temperature, and increase the operating time of the electronic device. The present study compares the thermal performances (TP) of three different heat sinks (simple, circular pin finned and copper foam) with NePCM (RT54HC/Al2O3) and varying Al2O3 nanoparticles concentrations (0.15–0.25 wt%) and heat fluxes (0.98–2.94 kW/m2) to optimize the overall device performance. The results show that at a heat flux (HF) of 0.98 kW/m2 and 0.25 wt% of Al2O3 nanoparticles (NPs), the base temperature of simple, circular pin finned and Cu foam heat sink was reduced by 21.3%, 25.03%, and 36.2%, respectively. The Cu foam heat sink (HS) has exceptional TP than the HSs without Cu foam. Accordingly, NePCMs are highly recommended in electronic devices for an optimized thermal management system.

An energy self-circulation system based on the wearable thermoelectric harvester for ART driver monitoring

With the popularity and application of Autonomous-rail rapid transit in China, the status of drivers has also attracted more attention to reducing the number of accidents on complex urban roads. The previously used sensors to monitor driver status require external power, limiting the further development and application of the sensor. This paper proposes a sensor energy self-circulation system based on a copper foam heatsink using the wearable thermoelectric harvester. The proposed method consists of a thermoelectric harvester, boost circuit, and sensor module. The thermoelectric harvester module uses the wearable thermoelectric harvester to convert the waste heat of the human body into electric energy, the copper foam heatsink is used to enhance the heat dissipation capacity, and the PDMS film is used to reduce the heat loss. The DC-DC boost circuit module uses the LTC3108 to pull up the voltage to the starting voltage of the sensor and realizes power management. The sensor module uses the ultra-low-power sensor ADLX362 to detect changes in acceleration values. The experimental results show that the maximum output power of the system to the human body at a wind speed of 1.5 m/s is 145.7 μW, which can realize the self-powered applications of the proposed sensor. The result proves the feasibility of a sensor energy self-circulation system using the wearable thermoelectric harvester based on a copper foam heatsink to monitor the status of drivers.

Investigation of thermal-hydraulic performance of metal-foam heat sink using machine learning approach

Metal foam heat sinks (MFHSs) are often used for electronic cooling because of their high specific heat transfer surface area, fluid mixing capability, and lightweight. Thermal-hydraulic performance of MFHS is known to be related to the morphological parameters of the metal foam (MF), physical dimensions of the heat sink, and coolant flow condition. Moreover, the highly random and complex geometrical nature of MFHS makes full-scale numerical simulation and experimental analysis expensive. In this paper, we have utilized machine learning (ML) methods to predict the thermal-hydraulic performance of MFHS, considering MF morphology, heat sink dimension, and coolant flow condition as input features. Considering local thermal non-equilibrium conditions for MFHS, a database of 1000 data points is generated utilizing a validated high-fidelity computational fluid dynamics/heat transfer (CFD/HT) model. The data sets consist of two non-dimensional descriptors, i.e., Nusselt number (Nu) and friction factor (f), along with the four input features such as MF morphological parameters, i.e., porosity and pore density, heat sink geometrical dimensions, i.e., hydraulic diameter (Dh) and flow condition, i.e., Reynolds number (Re). Five different ML-based regression models, namely k-nearest neighbor (KNN), random forest (RF), extreme gradient boosting (XGBoost), support vector regressor (SVR), and artificial neural networks (ANN), have been developed. Hyper-parameters of each ML model have been systematically optimized, and optimized model's performance have been compared using statistical score metrics and considering the initialization effect. Additionally, in order to demonstrate the robustness of the developed ML models, individual model performance has been evaluated by independent datasets. Results indicate that for testing datasets, all ML algorithms, except KNN, can predict the thermal-hydraulic performance of MFHS reasonably well, with a mean absolute percent error (MAPE) of about 4.59% and a 1.24 standard deviation (SD). However, SVR and ANN outperform other models for independent datasets with a MAPE of less than 3.1%.