Thermal Management Strategies Research Articles

Machine learning-based model for the intelligent estimation of critical heat flux in nanofluids

The rising demand for advanced energy systems requires enhanced thermal management strategies to maximize resource utilization and productivity. This is quite an important industrial and academic trend as the efficiency of energy systems depends on the cooling systems. This study intends to address the critical need for efficient heat transfer mechanisms in industrial energy systems, particularly those relying on pool boiling conditions, by mainly focusing on Critical Heat Flux (CHF). In fact, CHF keeps a limit in thermal system design, beyond which the efficiency of the system drops. Recent research materials have highlighted nanofluids’ superior heat transfer properties over conventional pure fluids, like water, which makes them a considerable substitution for improving CHF in cooling systems. However, the broad variability in experimental outcomes challenges the development of a unified predictive model. Besides, Machine Learning (ML) based prediction has shown great accuracy for modeling of the designing parameters, including CHF. Utilizing ML algorithms—Cascade Forward Neural Network (CFNN), Extreme Gradient Boosting (XGBoost), Extra Tree, and Light Gradient Boosting Method (LightGBM)— four predictive models have been developed and the benchmark shows CFNN’s superior accuracy with an average goodness of fit of 89.32%, significantly higher than any available model in the literature. Also, the iterative stability analysis demonstrated that this model with a 0.0348 standard deviation and 0.0268 mean absolute deviation is the most stable and robust method that its performance minorly changes with input data. The novelty of the work mainly lies in the prediction of CHF with these advanced algorithm models to enhance the reliability and accuracy of CHF prediction for designing purposes, which are capable of considering many effective parameters into account with much higher accuracy than mathematical fittings. This study not only explains the complex interplay of nanofluid parameters affecting CHF but also offers practical implications for the design of more efficient thermal management systems, thereby contributing to the broader field of energy system enhancement through innovative cooling solutions.

A Study of the Thermal Management and Discharge Strategies of Lithium-Ion Batteries in a Wide Temperature Range

The performance of lithium-ion batteries is greatly influenced by various factors within their operating environment, which can significantly impact their overall efficiency and effectiveness. In this paper, a multi-physics field electrochemical thermal model is established to measure the physical parameters of a battery module during the charge/discharge process. The effects of working temperature, current rate, and convective heat transfer coefficient are investigated by establishing an electrochemical and thermal model. The results are obtained by conducting numerous parameterized scans to analyze the system’s state across various operating conditions, enabling the determination of its temperature and the selection of appropriate cooling measures accordingly. Based on the internal and external conditions of battery operation, parameter selection corresponding to the operating range is divided into several stages, with thermal management strategies provided for each stage. The existing framework facilitates the design of battery packs equipped with efficient thermal management strategies, thereby enhancing the battery systems’ reliability and performance. Furthermore, it aids in establishing optimal operational and safety boundaries for batteries.

Investigation on performance enhancement of micro-channel separated heat pipe in data center: A coupled heat-mass-flow characterization approach

As data center continues to expand in scale and complexity, the demand for efficient heat dissipation solutions becomes increasingly critical. The utilization of micro-channel separated heat pipe is prevalent in data center cooling due to their low energy consumption and efficient cooling. This study aims to investigate the effects of different refrigerant flow rates, different inclination angles and different inlet vapor phase fractions on the heat transfer and flow characteristics of micro-channel separated heat pipe evaporator. Firstly, a simulation model of the heat pipe evaporator was established considering the heat-mass-flow coupling characteristics, and the fins were modeled and simplified without neglecting the enhanced heat transfer. Then, the experimental data are used to verify the established simulation model, and the error is within the acceptable range. Finally, scheme design and performance optimization research are conducted. Research on the inlet flow rate of R134a shows that when the inlet flow rate is 0.005 m/s, the outlet is superheated vapor. The presence of an inclination angle (0°-20°) in the evaporator not only significantly reduces the pressure difference between the outlet and the inlet (more than 30 %), but also improves the heat transfer coefficient and the refrigerant velocity magnitude. In addition, increasing the inlet vapor volume fraction promotes vapor bubble nucleation and reduces the pressure drop, but leads to the presence of outlet overheating. The findings of this study contribute valuable insights for advancing thermal management strategies in data center environments.

Multiphysics integrated model of NMC111 battery module for micro-mobility applications using PCM as intercell material

The widespread use of e-bikes and e-scooters powered by lithium-ion batteries in urban settings has heightened safety concerns, particularly the risk of thermal runaway, which can result in dangerous incidents. The surge in battery-related fire incidents highlights the critical need for a deep understanding of thermal runaway phenomena. This study addresses this imperative by introducing a Multiphysics model combining pseudo-bidimensional electrochemical for simulating electrical performance, lumped thermal model for simulating the heat transfer behavior inside the module, and a thermal runaway kinetic model for propagation evaluation. This approach facilitates precise predictions of battery performance and proactively addresses safety concerns by incorporating thermal behavior simulations and predicting potential thermal runaway events. The model proposed allows the evaluation of different strategies for improving battery safety and performance, such as phase change materials and thermal insulators. Simulations reveal that implementing sodium hydrogen phosphate dodecahydrate (Na2HPO4··12H2O) as an intercell material substantially enhances thermal management. This material reduced the maximum temperature of the battery module by up to 30% during critical thermal runaway events. Additionally, it slowed the rate of temperature increase by 50%, significantly decreasing the possibility of adjacent cells reaching thermal runaway conditions. The research findings demonstrate the effectiveness of advanced thermal management strategies using PCMs to prevent potentially catastrophic thermal events in battery modules typical of micro-mobility devices.

Lateral Heterostructure Formed by Highly Thermally Conductive Fluorinated Graphene for Efficient Device Thermal Management.

The continued miniaturization of chips demands highly thermally conductive materials and effective thermal management strategies. Particularly, the high-field transport of the devices built with 2D materials is limited by self-heating. Here a systematic control of heat flow in single-side fluorinated graphene (FG) with varying degrees of fluorination is reported, revealing a superior room-temperature thermal conductivity as high as 128W m-1 K-1. Monolayer graphene/FG lateral heterostructures with seamless junctions are approached for device fabrication. Efficient in-plane heat removal paths from graphene channel to side FG are created, contributing significant reduction of the channel peak temperature and improvement in the current-carrying capability and power density. Molecular dynamics simulations indicate that the interfacial thermal conductance of the heterostructure is facilitated by the high degree of overlap in the phonon vibrational spectra. The findings offer novel design insights for efficient heat dissipation in micro- and nanoelectronic devices.

Enhancing thermal performance in enclosures filled with nanofluids subjected to sinusoidal heating: a numerical study

ABSTRACT This study conducts a comprehensive numerical investigation into enhancing thermal transfer within square enclosures filled with water-based oxide nanoparticle suspensions, subjected to central sinusoidal heating. Further flow configuration, influenced by an inclined magnetic field, is designed with a focus on enhancing thermal efficiency for engineering applications. Key innovations include the application of sinusoidal heating elements to enhance thermal performance significantly. Computational analysis supported by finite element analysis, quantifies the impact of these parameters on flow dynamics and thermal transmission, presenting a substantial advance in the understanding of nanofluid-filled enclosure thermal management. The study reveals that the undulation of the heating element plays a crucial role in the heat transfer rate, with improvements observed as undulation increases. The introduction of magnetic fields further controls flow distribution and buoyancy effects, as demonstrated by our findings that an increase in the Rayleigh number correlates with enhanced convection, dominating the cavity's thermal dynamics. Additionally, the report outlines the conditions under which the Nusselt number increases, indicating enhanced thermal performance. These insights are pivotal for designing optimized heat transfer systems and energy-efficient applications, setting a new benchmark for thermal management strategies in practical engineering contexts.

Radiative cooling: Experimental and numerical analysis for enhanced thermal management strategies in engineering systems

AbstractThis study aims to fully evaluate the radiation effect in existing cooling systems. The research, a combination of experimental analysis and numerical simulations using ANSYS Fluent, examines the complexity of radiative cooling processes and their impact on thermal management in various engineering applications. The experiments began by carefully placing a 112.5 W heater into the thermal channel. Next, temperature measurements were made under various conditions. In particular, the use of black cotton fabric as the inner duct lining applied in the thermal channel stands out as an innovation that aims to optimize heat absorption by increasing radiative properties. The findings highlight the significant impact of radiation on cooling performance. A temperature drop of 2–3°C was observed in cooling under the effect of radiation. Additionally, numerical simulations reveal the feasibility of radiative cooling systems by providing valuable information about the flow dynamics and heat transfer mechanisms within the channel. The novelty of this work is its detailed examination of radiative cooling effects and its focus on its potential to optimize thermal management strategies in various engineering applications. Explaining the role of radiation in heat transfer and providing practical information to improve cooling efficiency demonstrates that this research brings important insight and lays the foundation for future advances in the field. Considering the urgent need for energy‐efficient cooling solutions and the increasing demand for sustainable engineering practices, the findings of this study will provide important insights for researchers and practitioners. This study provides innovative perspectives and solutions to address the increasing challenges of heat transfer and energy conservation in engineering systems. It makes a significant contribution to the field of thermal management by offering methodologies.

Indoor functional plywood with electrothermal response, flame retardancy, and moisture-proof performance and enhanced surface temperature with nano-SiO2 film

ABSTRACT Innovative wood-based composites have attracted considerable interest because of their potential applications in multifunctional indoor wood products. Flame-retardant electrothermal plywood (FR-Eplywood) with excellent Joule heat, flame retardancy, and moisture-proof performance was fabricated via a cold pressing process using carbon fiber paper as a heating element. The results showed that the bonding strength of FR-Eplywood in the air-dried state was 2.07 MPa. The FR-Eplywood exhibited outstanding low-temperature radiation performance and temperature uniformity, and the maximum temperature was 40.2°C and 57.9°C at 24 V and 36 V, respectively. Meanwhile, the flame retardancy performance was also significantly improved owing to the peak of heat release rate, and the total smoke release was reduced by 47.4% and 60.7%, respectively. Furthermore, FR-Eplywood can accelerate the discharge of water under low voltage. When the voltage was maintained at 36 V during 400 min of heating, the moisture content decreased from 26.8% to 1.7%, indicating that FR-Eplywood could inhibit mildew in humid environments through temperature management. This study provides a promising thermal management strategy for functional indoor wood products.

The potential of hyperbolic films for radiative heat transfer in micro/nanoscale

Thin films exhibit substantial potential in energy management and utilization as the development of micro- and nanofabrication technologies. It is well known that thermal radiation is one of the fundamental ways of energy transfer. However, the potential of hyperbolic films for radiative heat transfer is always ignored. Whether the radiative heat flux between hyperbolic films surpasses that of the bulk materials remains insufficiently explored. In this work, we theoretically investigate the radiative heat transfer between hexagonal boron nitride (hBN) at a separation from 20 ​nm to 2 ​μm. The results show that when the optical axis of hBN is oriented in-plane, the near-field radiative heat flux of hBN with a thickness of 10 ​nm exceeds that of hBN bulk by 47% and exceeds the blackbody limit by two orders of magnitude at a gap distance of 20 ​nm. The physical mechanism is attributed to the volume-confined hyperbolic polaritons can be excited in a higher wavevector space. Conversely, when the gap distance is 600 ​nm, the heat flux between films is considerably lower than that of bulk material. This work opens up potential avenues for developing hyperbolic film-dependent thermal devices and strategies for thermal management.

A PAM hydrogel surface-coated hydroponic bamboo evaporator with efficient thermal utilization for solar evaporation

Solar-driven interfacial water purification emerges as a sustainable technology for seawater desalination and wastewater treatment to address the challenge of water scarcity. Currently, the energy losses via radiation and convection to surrounding environment minimize its energy efficiency. Therefore, it is necessary to develop strategies to minimize the heat losses for efficient water purification. Here, a novel evaporator was developed through the in situ gelation of PAM hydrogel on the surface carbonized hydroponic bamboo (PSC) to promote energy efficiency. The inherent porous and layered network structures of bamboo, in synergy with the functional hydration capacity of PAM hydrogel, facilitated adequate water transportation, while reducing evaporation enthalpy. The PAM hydrogel firmly covered on the photothermal layer surface effectively minimized the radiation and convection heat losses, while further harvesting those thermal energy that would otherwise dissipate into the surrounding environment. The reduced thermal conductivity of PSC served as a thermal insulator as well, obstructing heat transfer to bulk water and thus diminishing conduction losses. Consequently, the rational designed PSC could efficiently convert solar energy to purified water, leading to the evaporation of 2.09 kg m−2 h−1, the energy efficiency of 87.6 % under one sun irradiation, and yielding 9.6 kg m−2 fresh water over 11 h outdoor operation. Moreover, the PSC also performs excellent salt rejection, and long-term stability at outdoor experiment. These results demonstrated high and stable solar evaporation performance could be achieved if turning heat losses into a way of extra energy extraction to further enhance the evaporation performance. This strategy appears to be a promising strategy for effective thermal energy management and practical application.

Experimental and parametric analysis of a novel hybrid thermal management strategy for cylindrical lithium‐ion cells

Experimental and parametric analysis of a novel hybrid thermal management strategy for cylindrical lithium‐ion cells

Circulating oil-immersed battery thermal management system for cylindrical lithium-ion battery module

Since the lifetime of lithium-ion battery (LIB) is directly related to the operating temperature, it is important to investigate efficient and safe thermal management strategies. This paper mainly studies the effects of pipe position and coolant flow rate on oil-immersed battery thermal management system (BTMS) during circulating cooling. In addition, the theoretical analysis of heat transfer in the 1 C, 1.5 C and 2 C discharge processes is carried out on the oil circulation cooling system. The study found that the temperature of the battery module submerged in the transformer oil dropped by about 34% compared to natural air cooling. In the 9 sets of pipe positions, the inlet and outlet pipeline positions are diagonally distributed, that is, the design of C 4, C 5 and C 6 pipeline positions shows good cooling performance as a whole. Under the condition of high rate discharge, changing the flow rate has a significant impact on the cooling performance of the battery module. The theoretical analysis shows that the influence of forced convection can be ignored in the oil-immersed cooling system at low Re, and with the increasing increase of Re, forced convection dominates the heat transfer of the system. This study provides a new supplement for the process safety of LIB and BTMS applications.

Physics of pressurized hydrogen spontaneous ignition in pipes containing bends of different angles

In the context of hydrogen-based energy storage systems, the safeguarding against spontaneous ignition during high-pressure hydrogen release is of paramount importance. This study delves into the thermal safety and management technologies pertinent to such systems by numerically investigating the effects of pipeline geometry on the risk of spontaneous ignition. Employing Large Eddy Simulation (LES) coupled with detailed chemical kinetics and a linear eddy model, the research assesses the impact of different pipe angles and burst pressures on ignition behavior. The simulations are validated against experimental data, ensuring the veracity of the findings. The results demonstrate a significant interplay between the ignition propensity and both the geometrical configuration of the pipeline and the pressure of hydrogen release. Notably, the emergence and interaction of transverse waves in pipe bends are revealed to amplify mixing processes, generating vortices that elevate the temperature and promote a conducive environment for chemical reactions leading to stable flame propagation. The ignition is shown to occur predominantly near the stoichiometric mixture ratio, suggesting a narrow ignition region. These insights are vital for enhancing the safety protocols and thermal management strategies of hydrogen-based energy storage systems, paving the way for safer and more efficient energy solutions.

CFD Analysis of Automobile Radiator Performance: Investigation of Heat Input, Mass Flow Rate, and Coating Thickness Effects

This research paper delves into the realm of Computational Fluid Dynamics (CFD) analysis to optimize the thermal performance of automobile radiators through the application of coatings. The study focuses on the impact of three different coating sizes, namely 50 micrometres, 80 micrometres, and 100 micrometres, aiming to enhance heat transfer efficiency and overall radiator performance. To systematically investigate the influence of these coatings on thermal behaviour, the L9 Orthogonal array is employed as a robust experimental design. The experimental methodology involves simulating the radiator's heat dissipation capabilities using CFD techniques, considering the interaction of fluid dynamics and heat transfer within the coated radiator. The L9 Orthogonal array provides a systematic and efficient approach to conducting experiments, allowing for the exploration of various coating combinations and their effects on thermal performance. The research not only analyses the impact of different coating sizes on the overall heat transfer efficiency but also seeks to identify optimal combinations that yield superior results. Insights gained from this study contribute to the development of advanced thermal management strategies in automotive engineering, aiming to enhance the cooling efficiency of radiators while maintaining operational and material constraints. Key findings highlight the significant role that coating thickness plays in augmenting the heat dissipation capabilities of automobile radiators. The outcomes of this research bear implications for the automotive industry, guiding future design considerations for improved radiator performance in terms of heat transfer efficiency, energy consumption, and overall system sustainability.

Design and On-Orbit Performance of the Payload Rack Thermal Management System for China Space Station Experimental Lab Module

An efficient and reliable spacecraft payload thermal management method is one of the key problems to build China Space Station (CSS). Aiming at the outstanding characteristics and difficulties of the payloads rack in the experimental lab module of CSS, in the aspects of thermal control interface, boundary constraint, scale quantity, space layout, diversity of temperature control, operation mode and working life, etc., a two-stage thermal management scheme based on single-phase fluid loop is proposed and constructed. A fluid drive unit is designed to drive the fluid circulation and health management of the module thermal control bus (TCB). In view of the different characteristics of the payload racks, three different types of second-stage thermal control systems are proposed, and different thermal control terminals are designed, in order to solve the problem of thermal control resource allocation and health management in payload racks. A method based on “pump bypass” and “valve resistance ratio” is used to control the flow rate of the thermal management system. Based on the overall scheme of the thermal management system and the developed flight products, on-orbit verification and data analysis are carried out. Flight verification shows that the key parameters of the fluid loop in the thermal management system on orbit are basically consistent with the ground data; the maximum deviation is 1.84%. The pressure control accuracy of the bypass system reaches ±2%, and the active heat transfer efficiency of the integrated thermal management system is over 83%, which can effectively meet the thermal control requirements of the two-stage payloads in the module and rack. After on-orbit flight verification, the designed thermal control system works well on orbit and exhibits good stability.

Thermal Management for a Stadium Power Supply Container Using a Rack-Level Air Cooling Strategy

This study investigates the airflow and thermal management of a compact electric energy storage system by using computational fluid dynamic (CFD) simulation. A porous medium model for predicting the flow resistance performance of the battery modules in a battery cabinet is developed. By studying the influence of rack shapes, the effects of heat exchanger arrangements and other parameters on the airflow and battery thermal distribution are analyzed. When applying a larger bottom air channel, the inlet flow uniformity of each battery cabin in the cabinet increases by 5%. Meanwhile, temperature standard deviation decreases by 0.18 while raising the flow rate from 3 m/s to 8 m/s, indicating better temperature uniformity in the battery cabin. When the charge–discharge ratio reaches 0.5 C, the temperature deviation of the entire cabinet significantly increases, reaching 8 K. Furthermore, a rack-level thermal management scheme is proposed to effectively reduce the thermal deviation of the container electric energy storage system and improve the overall temperature uniformity. Results reveal that the rack-level thermal management of the wavy cabinet in the electric storage container can effectively improve the thermal uniformity of the distributed battery cabin, and the overall thermal deviation is controlled within 1.0 K.

Design and optimization of battery and thermal management system for AC photovoltaic energy module

The utilization of renewable energy sources has increased due to concerns about climate change. However, injecting the power from renewable energy sources into grid-tied systems is challenging. The techno-economic analysis a photovoltaic (PV) energy systems is investigated. As a result, this paper presents AC-PV module for Grid-Tied and Off-Grid Scenarios via optimization, modeling, and test results. Even though the output of a PV panel is DC voltage, a three-port inverter and a lithium-ion battery pack are integrated with the back of the PV panel. They are packaged as a PV system module that makes the module output have AC voltage. Therefore, an optimized AC-PV module can be a solution for residential and commercial use, which are grid-tied systems; it can be very efficient for those without access to electricity, which is an off-grid system. An integrated battery and thermal management strategy is crucial for this AC-PV module. In the article, the battery capacity optimization, the electrical and the thermal model of the battery pack, battery heat generation model are discussed by using stochastic analysis techniques; the battery test results are also obtained to identify the models’ parameters and a control algorithm is proposed to extract the battery information such as temperature, current, voltage, SoC and SoH of the battery pack.

A comprehensive investigation of thermal management strategies in dissimilar micro-friction stir welding (dissimilar µFSW): Insights from numerical simulation and experimental observations

The increased heat dissipation rate from thin sheets and differences in material properties lead to difficulties in controlling the heat input in dissimilar micro-friction stir welding (dissimilar µFSW). As a result, improper material mixing and defect formation significantly increase, which deteriorates weld performance and escalates its rejection rate. This issue of thermal mismanagement is mitigated in the present work by utilizing suitable material positioning and tool offset strategies during the dissimilar µFSW of 0.5 mm thick AA 2024-T3 and AA 6061-T6. To date, post-weld analysis was predominantly utilized to derive the physics for explaining these strategies in dissimilar µFSW. However, for proper utilization of these strategies, it is important to comprehend the underlying process physics by investigating the parameters that evolved during the process, such as temperature distribution, material flow velocity, and material intermixing. The literature currently available lacks a systematic investigation in this direction. For this purpose, a 3-D thermo-mechanical model based on coupled Eulerian-Lagrangian formulation was employed in this study. The numerical results showed that an optimal temperature difference between the advancing and retreating sides facilitates achieving a higher degree of velocity symmetry with a uniform higher magnitude of velocity vectors. Importantly, this degree of velocity symmetry showed a good agreement with experimentally determined weld characteristics, namely macro and microstructures, and mechanical performance. By appropriate thermal management, a joint efficiency of 77.3 % (weld strength = 243.58 MPa) was obtained upon tensile loading, and the weld fractured from the heat-affected zone of the AA 6061-T6 side, exhibiting characteristics of ductile failure.

Multiphysics-informed thermal runaway model for estimating the pressure evolution induced by the gas formation in a lithium-ion battery

This study proposes a multiphysics-informed thermal runaway (TR) model for a lithium-ion battery to replicate TR phenomena by considering the evolution of the SOC and SOH, thermodynamics, chemical reactions, pressure evolution, vent, and ejection phenomena. This versatile model contributes to estimate both temperature and pressure evolutions, and thereby understand the underlying multiphysics of TR better by deploying three key features. First, the proposed model accounts for TR dependency on the SOC and SOH of a cell by controlling kinetic parameters of positive and negative active materials. Second, simple yet accurate governing equations of vent and ejection phenomena are coupled to complex and nonlinear thermodynamics, elaborating the TR characteristics predicted by the proposed model. Third, the proposed model directly couples the chemical reactions of the five main components to predict gas formation (CO, C2H4, CO2, H2, and CH4) and evolution because the pressure evolution is initiated by different reaction ratios of these components. Quantitative experimental validation with both nickel-manganese-cobalt and lithium–iron-phosphate cells shows that the maximum error for prediction of temperature and pressure evolution is 2.2 and 14.5 % respectively, confirming the accuracy and robustness of the proposed model. This study also includes in-depth discussions for the applications of the proposed model, including the early detection of TR and gas monitoring. These insightful discussions not only reveal the effectiveness of the proposed model but also provide guidelines for optimal battery thermal management strategies.

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

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