Heat Dissipation Mechanisms Research Articles

Research on comprehensive heat dissipation characteristics of AlSi7Mg TPMS heat sinks manufactured by laser powder bed fusion

The comprehensive heat transfer characteristics of triply periodic minimal surface heat sinks were investigated in this research, and triply periodic minimal surface structures were manufactured by laser powder bed fusion with AlSi7Mg powder. The average surface temperature, thermal resistance, heat transfer coefficient, and specific heat transfer coefficient of heat sinks were tested, and the heat dissipation mechanism was analyzed by finite element thermal flow analysis. The results of thehomogeneous triply periodic minimal surface show that Primitive has the best comprehensive heat transfer performance under forced convection, and Gyroid is the best without forced convection. Compared with homogeneous and gradient triply periodic minimal surfaces, the P-Quadratic ΙΙ structure has the best comprehensive heat transfer performance under forced convection and natural thermal conductivity. Compared with homogeneous Primitive, the average convection heat transfer coefficient of P-Quadratic ΙΙ is increased by 13.44 % ∼ 19.78 %. The finite element thermal flow analysis shows that the narrow tube effect of Bernoulli’s principle and eddy current enhanced the heat transfer performance of Primitive and gradient Primitive.

In vivo detection of spectral reflectance changes associated with regulated heat dissipation mechanisms complements fluorescence quantum efficiency in early stress diagnosis.

Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing-retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance-based detection of the 535-nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy-based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications.

Investigation of internal thermal distribution in inverted perovskite solar cell and improvement of its heat dissipation performance

Abstract COMSOL Multiphysics software was used to construct a numerical opto-electro-thermal coupling model to investigate the mechanisms of internal heat generation, conduction, and dissipation in inverted (p-i-n architecture) perovskite solar cells (PSCs). The research results indicate that Joule heating and Shockley-Read-Hall (SRH) recombination are the primary sources of heat, leading to significant accumulation of heat at the interfaces between the perovskite and the electron transport layer (ETL), as well as between the ETL and the electrode. This concentration of heat not only affects the performance of the device but also poses challenges for overall thermal management. Therefore, we compared four different top electrode materials (Ag, Cu, Al, and reduced graphene oxide) to assess their performance in terms of heat dissipation efficiency. The results showed that reduced graphene oxide (RGO) performed exceptionally well in heat dissipation efficiency, primarily due to its high thermal conductivity, which enables it to effectively reduce heat accumulation at the interfaces, thereby improving performance of PSCs. This finding provides important material selection criteria for optimizing the thermal management of PSCs.

Research on the Structural Design, Operating Characteristics, and Heat Dissipation Mechanism of Magnetic and Hydraulic Hybrid Couplers

Research on the Structural Design, Operating Characteristics, and Heat Dissipation Mechanism of Magnetic and Hydraulic Hybrid Couplers

Response of growth and chlorophyll fluorescence parameters of mulberry seedlings to waterlogging stress

This study aimed to investigate the adaptive mechanisms of mulberry (Morus alba) to waterlogged conditions, with a specific focus on the development of adventitious roots (ARs), alteration of growth strategies, and adjustment of chlorophyll fluorescence parameters. To achieve this goal, 4-year-old potted mulberry plants were selected for research, and a waterlogging simulation method was implemented. Four treatments were established to investigate the effects of varying water conditions on leaf waterlogging damage, the number of ARs, plant height, chlorophyll fluorescence parameters, and proton motive force (pmf) parameters in mulberry plants. These treatments included the control group (CK), shallow submerged group (SS), half-submerged group (HS) and deep submerged group (DS). Our results showed that (1) The number of ARs in each group increased with increasing waterlogging time. (2) Waterlogging stress inhibited the height growth of mulberry, and the changes in plant height in the HS and DS groups were significantly lower than those in the CK and SS groups. (3) The maximum photochemical quantum yield (Fv/Fm) in the HS and DS groups decreased significantly under waterlogging stress. The nonphotochemical quenching (NPQt) of mulberry leaves in the submergence group increased significantly in the early stage of waterlogging stress, and the NPQt in the submergence group increased continuously with increasing waterlogging time. (4) Thylakoid conductivity to protons (gH+) in the leaves of mulberry decreased significantly under waterlogging stress, whereas the steady-state rate of proton flux (vH+) and total electrochromic shift (ECSt) increased significantly. The morphological, physiological, and ecological responses of mulberry plants to waterlogging stress include the timely generation of ARs at the stem base, the adjustment of plant growth strategies, and the repair of photosynthetic response centers in leaves through heat dissipation and thylakoid acidification mechanisms.

Heat dissipation mechanism of the thermosyphon electric knitting needle

Heat dissipation mechanism of the thermosyphon electric knitting needle

Exploring Biomimetic Heat Pipes for Space Radiator Enhancement

This study investigates biomimetic heat pipes for space radiator applications, utilizing nature-inspired structures to potentially enhance heat transfer efficiency. The research addresses the imperative for improved heat dissipation mechanisms in nuclear space systems, crucial for effective thermal management. Heat pipes are passive heat transfer devices widely adopted for thermal control. The study aims to evaluate the effectiveness of a biomimetic heat pipe design in comparison to a traditional design while also validating the fabrication process through industry-made heat pipe comparisons. Innovative hot oil bath testing methods are employed to fabricate and test both heat pipe types, utilizing comprehensive thermal analysis, physical experiments, and validation techniques to assess heat transfer capabilities. Tests span varying temperature levels to analyze heat pipe behavior and performance. Findings suggest the potential for enhanced heat dissipation along the length of the biomimetic heat pipe, hinting at the biomimetic structure’s role in improving heat transfer. This study underscores the promise of biomimetic design principles and their potential for advancing heat pipe technology. Recommendations for further exploration include alternative materials, optimized testing procedures, and refined fabrication processes.

Simulation of temperature rise in low voltage winding of natural oil circulation transformer and analysis of oil flow heat dissipation

Abstract The heat dissipation performance of an oil-immersed transformer is the key to its stable operation. Winding loss is a crucial part of transformer heat loss, and winding heat dissipation greatly influences the rise in transformer temperature. In this paper, depending on the finite element method, the magnetic field distribution of a 66 MVA (225/26.4 kV) natural oil circulation transformer is analyzed, and the DC and eddy current losses of the low voltage winding are calculated. Based on the finite volume method, the temperature field distribution of the low-voltage winding is calculated, and the heat flux distribution of the contact surface between the disc insulation paper and the oil flow is obtained. It is found that there are transition points and extreme points between the upper and lower surface of the disc and the inner and outer surface of the disc, and the heat flux on the upper and lower surface of the disc conductor has obvious alternating oscillation. This study provides direction for further analysis and understanding of the heat dissipation mechanism and structural design of natural oil circulation transformers.

Numerical Analysis on Frictional Heat Effect in Polyether-Ether-Ketone (PEEK)/Steel Pair by using OpenFOAM Model

The PEEK material has been applied to a sliding bearing system in a power plant system because of its high mechanical durability. In the solid friction of the PEEK materials, the frictional heat becomes the important factor because the temperature increase due to the frictional heat causes the rapid increase of the frictional coefficient of the specimen. To maintain the low frictional coefficient of the PEEK materials, an effective cooling method for the PEEK materials needs to be developed. In this study, the passive cooling method, which attaches the heat sink to the PEEK materials, was suggested. For evaluating the suggested cooling method of the PEEK materials, the calculation model adopting OpenFOAM, which is open-source software, has been developed. Adopting some functions and libraries of OpenFOAM, the frictional heat, heat resistance, and heat transfer coefficient on the heat sink were modelled. The sliding bearing experiment was conducted and time variation of the temperature and friction coefficient in the ring specimen were measured. The temperature variation in the ring specimen was compared with the calculation result. From the numerical calculation results, the developed calculation model could simulate the temperature-time variation of the ring obtained in the experiment, when the variation of the frictional coefficient, heat resistance, and heat transfer coefficient was modelled appropriately. Based on the friction and wear test results, by applying a heat dissipation mechanism to the ring test piece, the calorific value of the PEEK material can be reduced, and it is stable. It was suggested that the friction was maintained.

Solar-Driven membrane reactors with wide temperature range for chemical looping dry reforming of Methane: Concept validation and one-dimensional analysis

Solar thermochemical fuel conversion technology offers a significant potential to mitigate the challenges of intermittency and variability inherent in solar energy utilization. Traditional two-step methane chemical looping processes for fuel production are often hampered by complex apparatus requirements, operational intermittency, and persistent temperature variations, contributing to energy loss. In contrast, the chemical looping dry reforming of methane (CL-DRM) membrane reactor technology, as developed in this study, facilitates continuous fuel synthesis under isothermal conditions. Through the construction and analysis of a one-dimensional + one-dimensional model for a single channel of this innovative reactor, the impact of structural and operational parameters on the reactor performance is elucidated. This model enables a swift prediction of the membrane reactor’s operational efficacy. The results indicate that the reactor sustains a high energy conversion efficiency across a broad temperature spectrum, thereby enhancing its adaptability to the dynamic conditions of solar energy input. Notably, temperature and feed ratio (RCH4/CO2) are pivotal determinants of the conversion rate and the concentration of products. At a temperature of 1000 °C, with an optimal RCH4/CO2 ratio of 1, the efficiency is projected to attain 78 %, considering heat dissipation and thermal recovery mechanisms. These results underscore the promise of the solar-driven CL-DRM membrane reactor as a viable and efficient method for solar fuel production. This study provides a new perspective on the design of continuous solar fuel conversion reactors.

Enhancing thermal management efficiency in robotics engineering: Exploring mechanisms, techniques, and modeling approaches

Thermal management is pivotal in robotics engineering, ensuring optimal performance and reliability of robotic systems. This comprehensive review explores various heat dissipation mechanisms, cooling techniques, and thermal modeling approaches employed in robotics engineering. Key topics include conduction-based, convection-based, and radiation-based heat transfer mechanisms, alongside liquid cooling, air cooling, and phase-change cooling techniques. Analytical thermal models, computational fluid dynamics (CFD) simulations, and finite element analysis (FEA) modeling are discussed for their roles in predicting thermal behaviors and optimizing heat dissipation strategies. By synthesizing these advancements, this review provides valuable insights into enhancing thermal management efficiency and ensuring the longevity of robotic systems.

Heat Dissipation Mechanisms in Hybrid Superconductor-Semiconductor Devices Revealed by Joule Spectroscopy.

Understanding heating and cooling mechanisms in mesoscopic superconductor-semiconductor devices is crucial for their application in quantum technologies. Owing to their poor thermal conductivity, heating effects can drive superconducting-to-normal transitions even at low bias, observed as sharp conductance dips through the loss of Andreev excess currents. Tracking such dips across magnetic field, cryostat temperature, and applied microwave power allows us to uncover cooling bottlenecks in different parts of a device. By applying this "Joule spectroscopy" technique, we analyze heat dissipation in devices based on InAs-Al nanowires and reveal that cooling of superconducting islands is limited by the rather inefficient electron-phonon coupling, as opposed to grounded superconductors that primarily cool by quasiparticle diffusion. We show that powers as low as 50-150 pW are able to suppress superconductivity on the islands. Applied microwaves lead to similar heating effects but are affected by the interplay of the microwave frequency and the effective electron-phonon relaxation time.

Research on the Influence of Biomimetic Patterns Surface on the Surface Temperature of Drum Brake Lining

Vehicles need to brake frequently on long downhill sections. In this case, the surface of the friction lining is prone to accumulating a large amount of heat, which will reduce the performance of the braking material and lead to braking failure. This article analyzes the heat generation and dissipation mechanism during the braking process of drum brakes based on the law of energy conservation, and establishes a thermal conductivity differential equation. Subsequently, with the honeycomb texture as the biomimetic target, circular, square, and honeycomb patterns with different parameters were designed on the surface of the friction lining, and a finite element model was established using Ansys Workbench. Thermodynamic coupling analysis shows that patterned friction lining can reduce the maximum temperature of the braking surface. Honeycomb patterns have better heat dissipation effects than circular and square patterns. Compared with non patterned brake pads, honeycomb patterns can reduce the maximum surface temperature of brake pads by 14.6%. When the surface area ratio of the honeycomb is 56.8%, its heat dissipation effect is the best.

Integrated heat dissipation mechanism design of electronic equipment cabinet based on flow and sound analysis

The electronic equipment cabinet is the main bearing platform of radar back equipment, normally using a forced convection cooling form. With the continuous increase of radar function and processing capacity, the total heat consumption of electronic equipment is getting higher and higher, and the fan speed is constantly increasing. Besides the noise of electronic equipment cabinet shows a trend of gradually increasing. To reduce cabinet noise from the source, this paper presents three structural forms of integrated heat dissipation mechanism, and uses FloEFD fluid heat transfer analysis software and COMSOL acoustic module to analyze the cabinet flow field and the cabinet sound field respectively. By comparing the cabinet noise characteristics under different structural forms, the analysis results show that the noise reduction effect of bilateral air duct structure is best.

Electrothermal Instabilities in Barium-Titanate-Based Ceramics

An electrothermal analysis for barium-titanate-based ceramics is presented, combining the Heywang–Jonker model for the electric resistivity with a heat dissipation mechanism based on natural convection and radiation in a one-dimensional model on the device level with voltage as the control parameter. Both positive-temperature-coefficient (PTC) and negative temperature coefficient (NTC) effects are accounted for through the double Schottky barriers at the grain boundaries of the material. The problem formulated in this way admits uniform and non-uniform multiple-steady-state solutions that do not depend on the external circuit. The numerical bifurcation analysis reveals that the PTC effect gives rise to several multiplicites above the Curie point, whereas the NTC effect is responsible for the thermal runaway (temperature blowup). The thermal runaway phenomenon as a potential thermal shock could be among the possible reasons for the observed thermomechanical failures (delamination fracture). The theoretical results for the NTC regime and the thermal runaway are in agreement with the experimental flash sintering results obtained for barium titanate, and 3% and 8% yttria-stabilized zirconia.

Fabrication and heat dissipation performance of diamond/Cu composite with diamond bars inserted in the normal direction

In this paper, a new type of diamond/Cu composite with diamond bars inserted in the normal direction is designed and prepared by vacuum brazing. In order to reduce the negative effect of the low thermal conductivity of Cu-Sn-Ti solder, diamond particles were added into the solder area. The microstructure, thermal conductivity, and heat dissipation performance of the diamond/Cu composite under water-free and water-cooling conditions were studied and compared. Besides, the heat dissipation mechanism of the composite was explored through finite element analysis. The results show that the diamond bars and diamond particles can be connected well by the CuSnTi solder, and the diamond particles scatter in the solder area. The TC tests show that the sample with 2000 mesh diamond particles has the highest TC (515.25 W/(m·K)). Besides, both the heating experiments on the electronic heating platform and the actual heat dissipation performance under water-cooling conditions affirm the excellent heat dissipation effect of the composite with 2000 mesh diamond particles. In conclusion, the diamond/Cu composite with diamond bars inserted vertically possess an excellent structural design, which is promising in heat dissipation material for electronic devices.

Analysis of Contact Thermal Resistance and the Use of Coatings on Heat Transfer in Cemented Carbide Metal Cutting Tools

Objective: The objective of this study is to investigate the thermal behavior of coated cutting tools in industrial turning processes, aiming to enhance machining efficiency and prolong tool lifespan. Theoretical Framework: The study is grounded in the concepts of heat transfer, thermally insulating coatings, and their impact on cutting tool performance. Key theories and models include thermal conductivity, thermal insulation, and heat dissipation mechanisms. Methodology: The research employs numerical simulation using the COMSOL® Multiphysics package to model transient heat transfer within coated tools and their holders. Thermal contact resistance at the tool-holder interface is also considered. Two coating configurations (Model 1 and Model 2) with different materials are analyzed, resulting in six simulation scenarios. Results and Discussion: The simulations demonstrate significant temperature reductions in the coated tools compared to uncoated ones, with Model 2 showing the most substantial decrease. These findings indicate the effectiveness of thermally insulating coatings in mitigating heat generation and improving tool performance. Research Implications: The study's findings have practical implications for the manufacturing industry, suggesting that the use of specific coatings can lead to higher cutting velocities and prolonged tool lifespan. These insights can inform decision-making in tool selection and process optimization. Originality/Value: This research contributes to the literature by providing a detailed analysis of the thermal behavior of coated cutting tools under extreme temperatures. The study's innovative approach and practical implications offer valuable insights for improving machining processes and tool performance.

Marine Plant Growth Promoting Bacteria (PGPB) inoculation technology: Testing the effectiveness of different application methods to improve tomato plants tolerance against acute heat wave stress

Regenerative agriculture aims to boost native biodiversity and ensure sustainable production. Plant Growth Promoting Bacteria (PGPB) enhance crop yield through improved nutrient use efficiency or stress tolerance. Utilizing synthetic bacterial communities (SynCom) tailored to specific challenges holds promise for enhancing plant resilience. However, challenges include designing microbial consortia and selecting SynCom application techniques. This study tested four PGPB SynCom application methods on tomato plants to evaluate their effectiveness in promoting plant resistance and recovery from short extreme heat waves. Non-invasive phenotyping techniques were used to assess plant responses to three delivery methods (watering, foliar spray, and alginate spheres immobilization) under heat stress. Plants treated with the marine PGPB SynCom through methods like leaf spraying or encapsulation in alginate spheres exhibited improved resilience in terms of Kautsky curve intensity and shape, indicating better photochemical apparatus function. These techniques also facilitated post-stress recovery. Deep photochemical analysis revealed SynCom-induced improvements in the plant's photochemical apparatus, particularly the PS II donor side. Moreover, it was also possible to observe that upon stress relief these two techniques, alongside the plants inoculated throughout watering were able to recover their photochemical profiles. Analysing the Fv/Fm values, plants inoculated through watering, alginate beads and leaf spray can be considered heat-tolerant, a characteristic conserved throughout the three sampling moments. Heat-wave exposure led to an increase in the energy absorbed by the non-inoculated plants as a counteractive measure to overcome the low energy use efficiency observed (low trapping and transported energy fluxes). The reduction in stress impact was attributed to SynCom's ACC-deaminase production, which lowered ethylene accumulation, promoting growth and photosynthetic efficiency. The study also noted reduced energy dissipation under stress relief, indicating efficient heat dissipation mechanisms due to SynCom application. Statistical models generated with the attained photochemical data allowed depicting specific fluorescence signatures of each thermal and inoculation treatment with a very high degree of accuracy, reinforcing that these different inoculation treatments have in fact different impacts on plant photochemistry but also provide a tool for future phenotyping assessments using the proposed inoculation techniques. Alginate bead based PGPB release emerged as an efficient, scalable technique with continuous benefits for plant growth and stress response.

Research on the flywheel clearance flow and heat transfer characteristics in a horizontal canned motor reactor coolant pump

Flywheel is an important component for the canned motor reactor coolant pump (RCP). The flywheel of horizontal canned motor reactor coolant pump (HRCP) is different from RCP’s flywheel. Its clearance width or different thermal conductivity structure would affect the flow structure of flywheel clearance flow, and then affect temperature distribution of the clearance, which would further affects the life and stability of flywheel. Therefore, it is necessary to analyze the flow and heat transfer characteristics of flywheel clearance flow in detail. This paper applies a Detached Eddy Simulation (DES) method to study the flywheel clearance flow of HRCP. The results show that the DES method can capture the small-scale vortex structure in turbulence Taylor-Couette flow and then give a more refined flow field morphology. The authors further study the regularity of flywheel clearance flow with different thermal conductivity structure, and the results indicate that optimizing thermal conductivity structure can effectively reduce flywheel’s temperature. The authors also investigate the heat dissipation mechanism of different flywheel clearance structures.

Intrinsic and Strain-Dependent Properties of Suspended WSe2 Crystallites toward Next-Generation Nanoelectronics and Quantum-Enabled Sensors.

Two-dimensional (2D) layered materials exhibit great potential for high-performance electronics, where knowledge of their thermal and phononic properties is critical toward understanding heat dissipation mechanisms, considered to be a major bottleneck for current generation nanoelectronic, optoelectronic, and quantum-scale devices. In this work, noncontact Raman spectroscopy was used to analyze thermal properties of suspended 2D WSe2 membranes to access the intrinsic properties. Here, the influence of electron-phonon interactions within the parent crystalline WSe2 membranes was deciphered through a comparative analysis of extrinsic substrate-supported WSe2, where heat dissipation mechanisms are intimately tied to the underlying substrate. Moreover, the excitonic states in WSe2 were analyzed by using temperature-dependent photoluminescence spectroscopy, where an enhancement in intensity of the localized excitons in suspended WSe2 was evident. Finally, phononic and electronic properties in suspended WSe2 were examined through nanoscale local strain engineering, where a uniaxial force was induced on the membrane using a Au-coated cantilever within an atomic force microscope. Through the fundamental analysis provided here with temperature and strain-dependent phononic and optoelectronic properties in suspended WSe2 nanosheets, the findings will inform the design of next-generation energy-efficient, high-performance devices based on WSe2 and other 2D materials, including for quantum applications.