Thermal Management System Research Articles

Characterization of Electrolyte Reduction Reactions on Freshly Plated Lithium Using Electrochemical Heat Flow Calorimetry

Electrochemical heat flow calorimetry can be used to measure the evolved heat during the operation of a lithium-ion battery cell. The data obtained are useful for the optimization of thermal management systems on the cell and system level, but they can also be used to detect and characterize parasitic reactions, such as unwanted reactions of the electrolyte. The heat evolved from a reversibly operated lithium-ion cell can be described as the sum of irreversible heat, resulting from cell polarization, and reversible heat, related to entropy changes.1 In order to quantitatively measure the contribution of a parasitic heat flow, which is usually small in comparison, the irreversible and reversible heat flow must be known to a high accuracy. Two main approaches have been reported in the literature to obtain such defined measurement conditions.2, 3 The first method requires the integration of the heat flow over a full charge/discharge cycle.2 This cancels the reversible heat flow contributions and enables an estimation of the total irreversible heat from the difference of the charge and discharge energies. The second method analyzes the heat flow during a voltage hold after the cell has reached a steady-state condition and exclusively exhibits parasitic processes.3 Both of these approaches allow for an estimation of the mean reaction enthalpies per mole of electrons when the parasitic heat is correlated to the irreversible capacity or to the parasitic current, respectively.In the present work, we introduce an approach to characterize the heat of the electrolyte reduction reactions on freshly plated lithium. For this, we measure the heat flow during overlithiation of an artificial graphite electrode in a half-cell, using our previously reported setup.4 Figure 1 shows the voltage profile and the measured heat flow for an exemplary experiment, where the graphite electrode is first fully lithiated and then overlithiated to induce significant lithium plating before the electrode is fully delithiated again. Both the voltage and heat flow curves show characteristic features indicating lithium plating (LP) and lithium stripping (LS).5 During continuous lithium plating we expect a significant contribution of a parasitic heat flow from the electrolyte reduction reactions on the newly exposed lithium surface. The here analyzed conditions enable a straightforward separation of this parasitic heat flow from the reversible and irreversible heat flow contributions from lithium plating: since lithium is being plated on already deposited lithium on the graphite electrode surfaces and simultaneously being stripped from the lithium metal counter electrode, the system can be considered a quasi-symmetrical cell. This means that the reversible heat flow contributions cancel out and that the irreversible heat flow from cell polarization can be calculated from the offset of the measured cell voltage from 0 V. In the present study, we analyzed the parasitic heat flow during lithium plating, changing different measurement parameters (e.g., degree of overlithiation, plating current, electrolyte) to gain insights into the interplay of lithium plating and electrolyte reactions. By a correlation to the irreversible capacity losses, the mean reaction enthalpy per mole of electrons can be estimated. Finally, the results were correlated to electrolyte reduction reactions postulated by gassing analysis from online electrochemical mass spectrometry (OEMS) measurements. The gas analysis allows for comparing electrolyte reduction pathways at larger potentials (~0.8 V vs. Li+/Li) during the formation of a pristine graphite surface as compared to electrolyte decomposition onto plated lithium at potentials around 0 V vs. Li+/Li. Acknowledgements We gratefully acknowledge the German Federal Ministry of Education and Research (BMBF) for its financial support within the AQua HysKaDi project (03XP0321B).

Bayesian Deep Operator Network-Based Optimization for Battery Thermal Management System

This study tackles the critical need for efficient thermal management in battery systems, a key factor in improving the lifespan and performance of electric vehicles and energy storage applications. A groundbreaking method is introduced by utilizing the Bayesian Deep Operator Network (B-DeepONet) framework to develop a surrogate model capable of predicting and optimizing thermal behavior in battery systems across various operating conditions.We first identify key variables that significantly influence the thermal management of battery packs. These variables lay the groundwork for generating simulation data through Finite Element Method (FEM)-based models. This data, spanning a broad range of battery configurations and thermal load scenarios, is crucial for training the surrogate model.The model, constructed within the B-DeepONet framework, efficiently maps diverse battery configurations and operating conditions to their corresponding temperature distributions, effectively capturing the complex thermal dynamics. Incorporating uncertainty quantification capabilities enhances the model’s predictive accuracy and reliability, enabling significant advancements in system design even when data availability is limited. This proves particularly advantageous when obtaining high-quality training data is difficult or economically unfeasible.Finally, the B-DeepONet-based surrogate model is employed to optimize the performance of battery thermal management systems, contributing to more efficient and sustainable energy solutions. This study not only advances predictive modeling in thermal regulation but also improves the ability to effectively manage thermal behaviors in complex battery systems. Figure 1

The Influence of Thermal Management Concepts on the Battery Behavior - Insights from a New Coupled Numerical Modelling Approach on the Battery Module Scale and Corresponding Experiments

Battery electric vehicles (BEVs) are the future mainstream drivetrain solution for the individual mobility sector. However, the fast charging capability of BEVs, which is seen as a key enabler for a broad customer acceptance and a convenient e-mobility is a remaining challenge in the development of battery systems. During fast charging, increased heat losses occur in the battery cells and the electrical connectors of a battery module. The battery thermal management then plays a crucial role to keep the battery temperature in the recommended range and to avoid accelerated degradation of the cells. Most of the conventional battery thermal management concepts in today’s BEVs are not efficient in managing the increased heat losses which leads to currently limited fast charging rates. Therefore, new thermal management solutions are being discussed and developed. A promising approach is the direct liquid cooling of batteries, also known as immersion cooling. With immersion cooling, the cells, cell tabs and electrical connectors are in contact with a dielectric fluid. Immersion cooling has the potential to increase the temperature homogeneity within and between the cells and to decrease or even prevent subsequent cell degradation.For the development of efficient thermal management systems for future BEVs and to use the full potential of concepts like immersion cooling, the influence of the thermal management on the battery cells must be understood and evaluated in detail. Considering that, a deep understanding of the interacting electrical, electrochemical, thermal and fluid dynamic phenomena occurring inside a battery module is required. Therefore, in this contribution, numerical simulations and corresponding experiments with battery modules in application-related setups are combined to study the effects of the thermal management on the battery behavior. The two fundamentally different concepts of immersion cooling and state-of-the-art bottom cooling are investigated as well as variations of each of those concepts. In the immersion cooled module, particular attention is paid to the fluid flow distribution and the effect different flow concepts on the thermal and electrochemical conditions in the cell.The numerical studies are based on a new coupled modelling approach (Fig. 1). Detailed thermal models of the 65 Ah automotive NMC/Si-Gr pouch cells are set up in a 3D CFD environment based on the analysis of the disassembly of the cell and the measurements of its thermophysical properties. Then, networks of electrochemical models of the cell are electrically and thermally coupled to the 3D models and the module components. This holistic approach allows for the investigation of e.g., the interaction of the cooling fluid flow with the current and temperature distribution and its effect on the local electrochemical cell behavior like the anode potential during fast charging.The corresponding experimental battery modules in a 3s2p configuration (Fig. 2) are explicitly designed and built for the validation of the numerical models. The cells and module components are equipped with extensive temperature measurements to capture thermal gradients within and between the cells. The modules are then installed and operated in separate climate chambers and connected to individual cooling circuits (Fig. 3) to ensure defined and equal boundary conditions as basis for the comparison of concepts and concept variations.The performance differences in various operating points including fast charging are demonstrated and analyzed. Furthermore, the variation of boundary conditions e.g., the volume flow rate or the fluid temperature allows for the analysis of relevant differences in the cooling concepts’ operating principles.The results from simulation and experiment illustrate the weak spots of the conventional concepts that are used in today’s BEVs. Furthermore, the numerical models reveal the critical local conditions inside the cells that are provoked by high loads in combination with inefficient thermal management concepts. Furthermore, the results show the benefits of immersion cooling over conventional concepts and its potential to increase the lifetime of battery systems by steering the battery temperature and temperature homogeneity with suitable fluid flow conditions. At the same time, the fast charging capability of BEVs can be increased significantly with immersion cooling.The good agreement of numerical and experimental results (Fig. 4) show that the presented modelling approach can be used as a tool for the design and the optimization of thermal management concepts. The application-related setup in this study ensures transferability of the findings from experiment and simulation to automotive applications and will help researchers and developers from industry and academia towards developing better thermal management solutions for BEVs. Figure 1

Changes in the Basic Metabolic Rate of the Crew under conditions of Eight Months Isolation in a Hermetic Object with a Moderately Hypercapnic Artificial Gas Environment. Message 1

Within the framework of the SIRIUS international project, a study of the basic metabolism of a gender-mixed crew in a sealed object with a moderately high content of carbon dioxide in the artificial atmosphere was conducted. Using mathematical methods, we estimated the basic metabolic rate of a crew of 5 people (3 men and 2 women) at rest for 240 days of isolation when simulating a flight to the Moon in the “SIRIUS-21” experiment. The period of isolation lasted from 4.11.2021 to 3.07.2022. BMR studies were performed twice in the background (on –38–35, –6 days), 7 times during the isolation period (23–25, 50–52, 84–86, 110–112, 154–156, 181–183, 222–224 day) and twice during the aftereffect period (+1–2, +8–9 days). It was found that the basic metabolism in isolation decreased by an average of 6 kcal/kg of body weight per day compared with natural environmental conditions. The crew was isolated from the effects of seasonal lighting changes in a sealed facility, the Ground-Based Medical and Technical Facility (NEK) of the Scientific Research Center of the Russian Federation - Institute of Biomedical Problems of the Russian Academy of Sciences, which does not have portholes, and where artificial lighting was created without seasonal changes. Inside the NEK, the comfort temperature was constantly maintained at +21–23 degrees Celsius and an artificial gas environment was formed, in which the oxygen content was maintained at 21%, carbon dioxide no more than 0.35%. In conditions of isolation from the action of these geophysical environmental factors, seasonal fluctuations in basal metabolism with a wave span of an average of 4 kcal /kg of body weight per day were detected: in the spring calendar season, the level of basal metabolism increased relative to the winter season. Seasonal local maximums and minimums of the basic exchange level for 2 calendar seasons (winter 2021/2022 and in spring 2022) were determined for each of the volunteers. The results obtained in this work can be applied in the field of space physiology to clarify the calculated oxygen reserves and caloric content of the crew’s rations for a long-term space mission, as well as in the design and programming of life support systems and thermal management systems for inhabited hermetic objects.

Dual solutions of hybrid nanofluid flow past a permeable melting shrinking sheet with higher-order slips, shape factor and viscous dissipation effect

Purpose This paper aims to explore dual solutions for the flow of a hybrid nanofluid over a permeable melting stretching/shrinking sheet with nanoparticle shape factor, second-order velocity slip conditions and viscous dissipation. The hybrid nanofluid is formulated by dispersing alumina (Al2O3) and copper (Cu) nanoparticles into water (H2O). Design/methodology/approach The governing partial differential equations (PDEs) are first reduced to a system of ordinary differential equations (ODEs) using a mathematical method of similarity transformation technique. These ODEs are then numerically solved through MATLAB’s bvp4c solver. Findings Key parameters such as slip parameter, melting parameter, suction parameter, shrinking parameter and Eckert number are examined. The results reveal the existence of two distinct solutions (upper and lower branches) for the transformed ODEs when considering the shrinking parameter. Increasing value of Cu-volume fraction and the second-order velocity slip enhances boundary layer thicknesses, whereas the heat transfer rate diminishes with rising melting and suction parameters. These numerical results are illustrated through various figures and tables. Additionally, a stability analysis is performed and confirms the upper branch is stable and practical, while the lower branch is unstable. Practical implications The analysis of hybrid nanofluid flow over a shrinking surface has practical significance with applications in processes such as solar thermal management systems, automotive cooling systems, sedimentation, microelectronic cooling or centrifugal separation of particles. Both steady and unsteady hybrid nanofluid flows are relevant in these contexts. Originality/value While the study of hybrid nanofluid flow is well-documented, research focusing on the shrinking flow case with specific parameters in our study is still relatively scarce. This paper contributes to obtaining dual solutions specifically for the shrinking case, which has been less frequently addressed.

Research progress on efficient battery thermal management system (BTMs) for electric vehicles using composite phase change materials with liquid cooling and nanoadditives

Research progress on efficient battery thermal management system (BTMs) for electric vehicles using composite phase change materials with liquid cooling and nanoadditives

Mechanical-thermal coupling design on battery pack embedded with concave quadrilateral cellular structure

To comprehensively investigate mechanical-thermal coupling properties and function-oriented design of battery pack, a novel battery pack with triangular micro-channel cold plate and the optimal embedded concave quadrilateral cellular structure (CQCS) is proposed. Firstly, mechanical properties of CQCS are derived based on beam theory and homogenization theory. Then, thermal conductivity expressions of the CQCS are derived in accordance with Maxwell-Eucken model and negative thermal expansion design of the CQCS is ingeniously conducted to inhibit thermal runaway of battery pack. Moreover, the relations between mechanical properties and thermal properties of CQCS are innovatively investigated through the medium of structural parameters of CQCS. Secondly, modal analyses, collision analyses on conventional battery pack are conducted. Meanwhile, thermal characteristics of battery modules are derived and temperature field distributions are acquired through simulation analysis to provide reference for the design of thermal management system. Subsequently, the embedded CQCS is taken as the medium to conduct mechanical-thermal coupling design of battery pack. Multi-objective optimization models of the CQCS between battery cells and the CQCS between modules are established to obtain the optimal CQCS with the needs of high heat dissipation efficiency, superior temperature uniformity, outstanding collision performances, and more lightweight space of battery pack. Moreover, a convection triangular micro-channel cold plate is chosen as heat dissipation structure and variable density design of micro-channel cold plate is executed to ensure heat dissipation efficiency and temperature uniformity of battery pack. Eventually, the mechanical performances and thermal performances are compared to verify the superiority of the proposed novel battery pack. Compared with conventional battery pack, lower stress levels and more uniform stress distributions can also be achieved, and the resonance between battery pack and autobody can also be avoided effectively. Moreover, compared with conventional battery pack, the maximum temperature differences of battery pack with the optimal CQCS decrease by 10 %, 8.7 %, 10.91 % and 8.75 %, which demonstrates the superiority of the embedded CQCS in decreasing maximum temperature difference of battery pack. Moreover, the temperature differences of novel battery pack decrease by 26.67 %, 27 %, 28.57 %, and 32.88 % in comparations with those of battery pack with the optimal CQCS, which proves that variable density design on triangular micro-channel cold plate can improve temperature uniformity of battery pack effectively.

Multi-objective optimization of cold plate with spoiler for battery thermal management system using whale optimization algorithm

With the high population of electric vehicle adoption, precisely controlling the temperature of the battery modules is essential to provide long-term sustainability and reliability. In the amount of battery thermal management techniques, adding spoilers is a promising method for enhancing the heat transfer performance of cold plates, but the performance of the system is highly sensitive to different geometry parameters. In this study, heat transfer performance for the cold plates battery thermal management system with a tesla flow channel was numerically and experimentally investigated with a focus on the geometry parameters, including spoiler length (L), mounting position (X), and coolant flow rate (ν). A modified heuristic-based swarm intelligence multi-objective optimization algorithm is proposed to obtain the optimal spoiler parameters. The results show the maximum temperature of the battery module is reduced by 3.12 ℃ after adding the spoiler. The optimization spoilers maintain the maximum temperature of the battery module below 30.9 ℃, and the best spoiler parameters as L = 5.10 mm, X = 14.3 mm, and v = 1.186 × 10-2 m/s. This study uses a heuristic-based swarm intelligence multi-objective optimization algorithm to investigate the optimization process of the spoiler structural parameters and provides guidance for the application of advanced multi-objective optimization algorithms in cold plate design.

Cooling high power electronics using dynamic phase change material

Phase change materials (PCMs) offer effective transient cooling due to their high latent heat of fusion and energy density. Unfortunately, PCMs generally have relatively low thermal conductivity, impeding effective heat dissipation from the heat source and limiting their power density. This work uses dynamic PCM (dynPCM) cooling for thermal management of high power electronics. DynPCM cooling uses pressure-enhanced close-contact melting of a PCM. The applied pressure causes liquid PCM to be pumped away from the heat transfer surface, maintaining a thin melt layer and high heat transfer. Through experimental investigations with a circuit board mounted 2 × 2 array of gallium nitride (GaN) power transistors integrated with heat spreaders of different thicknesses, we evaluate the cooling performance of dynPCM across various device heat dissipation levels (4.4 W/cm² to 46.6 W/cm²) and under both homogeneous and heterogeneous heating conditions. Using paraffin as the PCM, we explore the effects of different pressures (0 Pa, 750 Pa, and 7.5 kPa) on dynPCM cooling effectiveness. DynPCM significantly enhances cooling for electronics operating at high power, achieving over a 50 % reduction in steady-state junction temperature when compared to both traditional air-cooled and hybrid PCM-cooled systems at a 32.4 W/cm² individual GaN device power loss. We developed a reduced-order thermal resistance model to assess heat transfer from the electronic devices through the heat spreader into the dynPCM. The model helps to illustrate the critical role of the heat spreader design and PCM geometry on cooling performance, offering design guidelines for dynPCM thermal management systems. This work highlights the potential of dynPCM as a thermal management strategy for high-power electronic devices, facilitating the advancement of more effective cooling methods for a variety of applications.

Multi-objective decoupling control of thermal management system for PEM fuel cell

Operating temperature is an important factor that affects the efficiency, durability, and safety of proton exchange membrane fuel cells (PEMFC). Thus, a thermal management system is necessary for controlling the appropriate temperature. In this paper, a novel thermal management system based on two-stage utilization of cooling air is first established, whose core characteristic is utilizing the temperature difference between the cooling air leaving the main radiator and the auxiliary radiator. The novel thermal management system can reduce the parasitic power of the fan by 59.27 % and improve the temperature control effect to a certain extent. The traditional feedforward decoupling control based on system identification is first adopted to control the temperature and surpasses dual-PID on all the 5 indexes, which are Integral Absolute Error Criterion (IAE) of temperature difference, IAE of inlet coolant temperature, parasitic power of fan, average overshoot of temperature difference and average overshoot of inlet coolant temperature. The multi-objective decoupling control based on multi-objective optimization is then proposed to further improve the temperature control effect on the basis of traditional feedforward decoupling control. The above 5 indexes are chosen as the optimization objectives, the decoupling coefficients are chosen as the decision variables, and the Pareto set is obtained by NSGAⅡ and NSGAⅢ. The results show that the proposed multi-objective decoupling control has the main advantages as follows: (1) It can provide comprehensive optimization options for different design preferences; (2) It can significantly optimize a certain objective while other objectives are not too extreme; (3) It has the ability to surpass traditional feedforward decoupling control on all the 5 indexes; (4) It does not rely on the system identification.

Enhancing high-density battery performance through innovative single-phase spray technology in immersion cooling systems

The flow field organization in liquid-cooled BTMS (Battery Thermal Management System) is crucial to the thermal performance of lithium-ion batteries. This study introduces an innovative single-phase spray technology to optimize the flow field and enhance thermal characteristics in BTMS. Using Computational Fluid Dynamics simulations, key factors such as dielectric fluid type, nozzle diameter, spray angle, and nozzle position are analyzed. Novec 7500 is identified as the optimal dielectric fluid, with thermal conductivity and viscosity playing significant roles. Response Surface Analysis and the entropy weight TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) determine optimal conditions: a 0.47 mm nozzle diameter, 0 mm nozzle offset, and an 88.16° spray angle. These parameters reduce the maximum battery temperature to 25.43 °C and minimize the temperature gradient to 3.41 °C, achieving reductions of 14.20 % and 57.74 %, respectively, compared to non-spray systems. Furthermore, the system reduces the maximum temperature of a 36-cell battery module by 27.28 % to 25.33 °C and the maximum temperature difference by 69.39 % to 4.35 °C. The optimized spray cooling technology is effective for smaller battery stacks and demonstrates the potential to maintain high cooling efficiency in complex systems, providing a solution for BTMS.

Analysis and optimization of thermal management system for cylindrical power battery based on distributed liquid cooling plates

Analysis and optimization of thermal management system for cylindrical power battery based on distributed liquid cooling plates

Performance and Efficiency Evaluation of a Secondary Loop Integrated Thermal Management System with a Multi-Port Valve for Electric Vehicles

Recently, battery electric vehicles (BEVs) have faced various technical challenges, such as reduced driving range due to ambient temperature, slow charging speeds, fire risks, and environmental regulations. This numerical study proposes an integrated thermal management system (ITMS) utilizing R290 refrigerant and a 14-way valve to address these issues, proactively meeting future environmental regulations, simplifying the system, and improving efficiency. The performance evaluation was conducted under high-load operating conditions, including driving and fast charging in various environmental conditions of 35 °C and −10 °C. As a result, the driving efficiency was 4.82 km/kWh in high-temperature conditions (35 °C) and 4.69 km/kWh in low-temperature conditions (−10 °C), which demonstrated higher efficiency than the Octovalve-ITMS applied to the Tesla Model Y. Furthermore, in fast charging tests, the high voltage battery was charged from a 10% to a 90% state of charge in 26 min at 35 °C and in 31 min at −10 °C, outperforming the Octovalve-ITMS-equipped Tesla Model Y’s fast charging time of 27 min under moderate ambient conditions. This result highlights the superior fast-charging performance of the 14-way valve-based ITMS, even under high cooling load conditions.

Exploration on the liquid-based energy storage battery system from system design, parametric optimization, and control strategy

Lithium-ion batteries are increasingly employed for energy storage systems, yet their applications still face thermal instability and safety issues. This study aims to develop an efficient liquid-based thermal management system that optimizes heat transfer and minimizes system consumption under different operating conditions. A thermal-fluidic model which incorporates fifty-two 280 Ah batteries and a baffled cold plate is established. The reliability of battery heat generation is confirmed experimentally, with a maximum deviation of 14.8 %. Then, comparative studies are performed to evaluate the impacts of cold plate structure and attachment on thermal management performance. Results found that while side-attachment shows better heat transfer, bottom-attachment coupled with a baffled cold plate reduces the temperature gradient and power consumption at both cooling and preheating scenarios. Furthermore, the effects of flow rate and inlet temperature are studied systematically, and a decision making method is utilized to assist in multi-attribute optimization. Finally, a surrogate model is proposed to unveil the collaborative effects between these factors. Based on this, an optimal thermal management strategy with controllable flow rate and inlet temperature is obtained according to ambient temperatures. The proposed framework provides a feasible approach to improve the design and control of liquid-based battery thermal management.

Electric Vehicle Energy Management via Traffic Light Detection and Segmental Velocity Forecasting

Abstract Predictive-based power control has been widely recognized as a promising approach to boost driving range and improve system-level energy efficiency for electric vehicles (EVs), in which vehicle velocity forecasting generally serves as a preliminary input to optimally schedule the operations of varying onboard electrical and thermal systems. A segment-based velocity forecasting approach for individual commuting vehicles developed in this study reveals that it is challenging to forecast the velocity at intersection segments only using the velocity data. To address this challenge, this study seeks to develop a YOLO-V2-based object detection deep network to recognize the traffic lights in advance and leverage the detected signals to establish a forecasting model that integrates with the probability-based hybrid forecasting approach. The case study results show that the traffic light detection-based forecasting model can significantly improve the forecasting accuracy for intersection segments. Based on the forecasting velocity 5–15 s ahead, the effectiveness of model predictive control-based energy management strategy is further evaluated with a liquid-based battery thermal control system. The proposed battery thermal management system (BTMS) model shows promising results in maintaining battery temperature within an appropriate range, thus improving the overall energy efficiency of the EV. Moreover, a traffic light-based real-time energy management framework is developed to directly control the power demand from the air conditioning (AC) system.

Heat transfer optimization using computational insights into nodal/saddle point flow patterns of tera-hybrid nanofluid containing microbes in a cylindrical shells

Tetra hybrid nanofluids enhance heat transfer efficiency in advanced thermal management systems, benefiting industries like electronics cooling, automotive, aerospace, and renewable energy. In this study, we examine the impact of magnetohydrodynamic tetra-hybrid nanofluid on nodal/saddle stagnation points in a rounded cylinder with a sinusoidal radius. The analysis focuses on optimizing energy and mass transfer rates around a circular cylinder with a sinusoidal surface, simulating thermal processes in biological systems. By utilizing similarity variables, a complex set of nonlinear partial differential equations is transformed into ordinary differential equations and solved numerically using MATLAB's bvp4c solver. The effects of several parameters are discussed graphically for the nodal stagnation point as well as numerically for both the nodal and saddle points. At R=4.5, the heat transfer rate for the tetra hybrid nanofluid shows a 1.36 % increase compared to the nanofluid, underscoring the enhanced thermal efficiency of hybrid nanofluids in radiative conditions. indicates that the application of a magnetic field, combined with variations in d, results in significant improvements in shear stress and heat transfer, reflecting enhanced velocity and thermal profiles compared to Madhukesh et al. (Gangadhar et al., 2024) [21]. The results indicate that increasing ϕ1 enhances the Nusselt number and improves heat transfer, while the accompanying rise in flow resistance typically leads to a decrease in mass transfer rate.

Theoretical analysis and experimental validation of optimal vapor injection conditions for a low-pressure ratio scroll compressor

This study investigates the impact of vapor injection parameters and positions on the performance of a low-pressure ratio scroll compressor in electric vehicle thermal management systems under extremely low temperatures. The research combines experimental and simulation methods to analyze five injection ports designed at different positions. Key performance metrics, including mass flow rate, discharge temperature (Tdis), coefficient of performance (COP), compression work, and heating capacity (Qh) were evaluated under various conditions. A low-pressure ratio (scroll number N = 2) vapor injection scroll compressor was designed with an optimized injection port configuration. This design was rigorously validated through experimental results, confirming its efficacy. Notably, the findings reveal that the enhancement in Qh and COP is more pronounced in extremely low-temperature working conditions compared to non-injection conditions, with improvements of 10.7 % and 4.6 %, respectively. Compressor performance increases with increasing vapor injection pressure, and compressor speed and performance increment are more significant under low-temperature working conditions. Finally, an injection coefficient, denoted as k, is proposed to determine the optimal injection pressure for diverse discharge and suction pressures in cold climates. According to the experimental results, the value of k associated with the best heating COP ranges between 0.65 and 0.85.

Gold Nanoparticles: Multifunctional Properties, Synthesis, and Future Prospects.

Gold nanoparticles (NPs) are among the most commonly employed metal NPs in biological applications, with distinctive physicochemical features. Their extraordinary optical properties, stemming from strong localized surface plasmon resonance (LSPR), contribute to the development of novel approaches in the areas of bioimaging, biosensing, and cancer research, especially for photothermal and photodynamic therapy. The ease of functionalization with various ligands provides a novel approach to the precise delivery of these molecules to targeted areas. Gold NPs' ability to transfer heat and electricity positions them as valuable materials for advancing thermal management and electronic systems. Moreover, their inherent characteristics, such as inertness, give rise to the synthesis of novel antibacterial and antioxidant agents as they provide a biocompatible and low-toxicity approach. Chemical and physical synthesis methods are utilized to produce gold NPs. The pursuit of more ecologically sustainable and economically viable large-scale technologies, such as environmentally benign biological processes referred to as green/biological synthesis, has garnered increasing interest among global researchers. Green synthesis methods are more favorable than other synthesis techniques as they minimize the necessity for hazardous chemicals in the reduction process due to their simplicity, cost-effectiveness, energy efficiency, and biocompatibility. This article discusses the importance of gold NPs, their optical, conductivity, antibacterial, antioxidant, and anticancer properties, synthesis methods, contemporary uses, and biosafety, emphasizing the need to understand toxicology principles and green commercialization strategies.

Energy Sources and Battery Thermal Energy Management Technologies for Electrical Vehicles: A Technical Comprehensive Review

Electric vehicles are increasingly seen as a viable alternative to conventional combustion-engine vehicles, offering advantages such as lower emissions and enhanced energy efficiency. The critical role of batteries in EVs drives the need for high-performance, cost-effective, and safe solutions, where thermal management is key to ensuring optimal performance and longevity. This study is motivated by the need to address the limitations of current battery thermal management systems (BTMS), particularly the effectiveness of cooling methods in maintaining safe operating temperatures. The hypothesis is that immersion cooling offers superior thermal regulation compared to the widely used indirect liquid cooling approach. Using MATLAB Simulink, this research investigates the dynamic thermal behaviour of three cooling systems, including air cooling, indirect liquid cooling, and immersion cooling, by comparing their performance with an uncooled battery. The results show that immersion cooling outperforms indirect liquid cooling in terms of temperature control and safety, providing a more efficient solution. These findings challenge the existing literature, positioning immersion cooling as the optimal BTMS. The main contribution of this paper lies in its comprehensive evaluation of cooling technologies and its validation of immersion cooling as a superior method for enhancing EV battery performance.

Experimental Study on Heat Transfer Characteristics of a ⊥-shaped Oscillating Heat Pipe Used in the Battery Thermal Management System

This paper introduces a ⊥-shaped oscillating heat pipe (OHP) with the purpose of improving the volumetric utilization of the battery thermal management system (BTMS) for electric vehicles. Distinguished from standard OHP structures, the evaporator and condenser sections of the ⊥-shaped OHP are oriented vertically in spatial arrangement. Experimental investigations were conducted on two types of ⊥-shaped OHPs and a standard OHP, employing filling ratios from 13.1% to 32.6%, working fluid mixtures of acetone with methanol, ethanol, and water, and thermal loads from 10 to 100W. The results indicate that all the OHPs with an acetone filling ratio of 19.6% exhibit minimum thermal resistance at 30W. When employing mixed working fluids, the acetone-ethanol and acetone-methanol combinations display the least and most temperature fluctuations, respectively. The OHP with mixed working fluids achieves no more improved thermal performance than the use of acetone. As the heating power increases, the operational stability of the ⊥-type OHP improves, however, the trend is opposite for the R-⊥-type OHP. In comparison to the standard OHP, the ⊥-type OHP demonstrates stronger oscillation stability at 100W and achieves a 3.3°C lower maximum temperature on the heat collector plate.