Passive Thermal Management System Research Articles

The intrinsic flame retardant multifunctional composite phase change material with phosphorus pentoxide for battery thermal safety system

The temperature distribution has severely affected the performance of lithium-ion battery modules in electric vehicles (EVs), composite phase change material (CPCM) with excellent temperature controlling function as a passive battery thermal management system is essential to ensure the safety of battery module. In this study, the polyethylene glycol phosphate ester (PEGP) has been synthesized by esterification of phosphorus pentoxide and polyethylene glycol through the reaction of PEGP and melamine (MA), the network crosslinking structure has been built to greatly improve the anti-leakage performance. The flame-retardant CPCM containing PEGP/expanded graphite /epoxy resin/MA (PPEM) has been successfully designed and prepared. The results indicate that PPEM2 containing 20 wt% melamine and 7 wt% epoxy resin exhibit excellent antileakage and prominent flame retardant properties comprehensively. It should be noted that the peak heat release rate of PPEM2 has been reached to 352.41 KW/m2, which is obviously decreased by 47.55 % comparing with pure PEG. The main reason is that the grafting flame retardant elements (P) and melamine onto polyethylene glycol molecular chain by chemical reaction. In addition, it can maintain the operating temperature below 36 °C at 23 A discharge current. The battery module with PPEM2 can transfer the heat timely and promptly, exhibiting outstanding flame-retardant effect to avoid thermal runaway. With these prominent performances, this intrinsic flame-retardant CPCM can not only exhibit an excellent thermal management effect but also provide a promising approach to inhibit the thermal runaway propagation.

Nano-Enhanced Graphite/Phase Change Material/Graphene Composite for Sustainable and Efficient Passive Thermal Management.

Passive battery thermal management systems (BTMSs) are critical for mitigation of battery thermal runaway (TR). Phase change materials (PCMs) have shown promise for mitigating transient thermal challenges. Fluid leakage and low effective thermal conductivity limit PCM adoption. Furthermore, the thermal capacitance of PCMs diminishes as their latent load is exhausted, creating an unsustainable cooling effect that is transitory. Here, an expanded graphite/PCM/graphene composite that solves these challenges is proposed. The expanded graphite/PCM phase change composite eliminates leakage and increases effective thermal conductivity while the graphene coating enables radiative cooling for PCM regeneration. The composite demonstrates excellent thermal performance in a real BTMS and shows a 26% decrease in temperature when compared to conventional BTMS materials. The composite exhibits thermal control performance comparable with active cooling, resulting in reduced cost and increased simplicity. In addition to BTMSs, this material is anticipated to have application in a plethora of engineered systems requiring stringent thermal management.

Optimization of cutting parameters in manufacturing of polymeric materials for flexible two-phase thermal management systems

Abstract This research study with an extensive literature review represents a comprehensive multi-criteria analysis for optimizing the cutting parameters in the manufacturing of flexible two-phase passive thermal management systems (FTP-TMS) using thermoplastic materials. Recognizing the critical role of thermoplastics in FTP-TMS due to their inherent flexibility and lightweight properties, this research focuses on the precision cutting of polypropylene, polyethylene, and polyvinyl chloride using CO2 laser technology. The study is structured into three distinct phases. Initially, an experimental setup was conducted to cut 2 mm thick thermoplastic materials with varying power and cutting speed parameters. Subsequently, the SWARA method was employed to weight the criteria, followed by the application of seven different multi-criteria decision-making (MCDM) methods for optimization. The final phase involved a detailed analysis of the outputs, including ranking, correlation, and sensitivity analyses. The findings indicate that cutting polypropylene with a 90 W power setting and a speed of 15 mm s−1 yields the most optimal results. This study fills a significant gap in the existing literature by providing a dedicated analysis for thermoplastics in FTP-TMS manufacturing. The insights gained are pivotal for standardizing manufacturing practices and enhancing the design and fabrication of flexible thermal management solutions, offering substantial benefits to sectors like electronics, aerospace, and automotive industries.

Design and Optimization of Accumulator Pack

For an electric scooter, a lithium-ion battery with a Acro Butyl-nitrate (ABS) temperature management system was developed. Without the use of active cooling components like a fan, a blower, or a pump used in air/liquid-cooling systems, passive thermal management systems employing ABS can regulate the temperature excursions and maintain temperature uniformity in Li-ion batteries. Therefore, this new type of thermal management system can provide the benefits of a small, light, and energy-efficient system. The simulation results for a Li-ion battery sub-module with twenty 18650 Li-ion cells encased in ABS and a melting point of 114 to 120 °C are displayed. There are many important advantages to using aluminium fins manufactured from 0.7mm thick aluminium sheet between the battery cells in an accumulator pack. The relevance of them is explained in the following ways: Accumulator packs, particularly those used in high-power applications like scooters, can produce large amount of heat when in use. The performance, longevity, and safety of battery cells are all significantly impacted by heat. Aluminium fins serve as heat sinks and enhance heat dissipation by boosting the amount of heat-transfer surface area. Heat can be effectively transferred from the cells to the fins thanks to the thin aluminium sheet. Temperature Control: Battery cell efficiency and longevity depend on maintaining their temperature within a favorable range. By releasing more heat, aluminium fins assist in controlling the temperature. The fins aid in preventing overheating and preserving a more constant operating temperature by efficiently draining heat from the cells. Thermal Uniformity: The accumulator pack's thermal uniformity is enhanced by the inclusion of aluminium fins between the battery cells. Variations in cell temperature can cause performance imbalances and lower pack efficiency because uneven heat distribution can cause temperature differences among the cells. The fins aid in the even distribution of heat throughout the cells, reducing temperature variations and fostering consistent performance. Reduced Hotspots: Hotspots are small, high-temperature regions inside a battery pack that can hasten degradation and pose safety issues. Aluminium fins aid in heat dissipation, which reduces the development of hotspots. The fins' increased surface area enables more effective heat transport, which lowers the possibility of localized temperature accumulation. Improved Safety: Effective heat dissipation with aluminium fins can aid in accumulator packs' increased safety. Battery cells may experience thermal runaway or other dangerous situations as a result of high temperatures. The risk of thermal incidents is decreased by maintaining lower cell temperatures, improving operational safety in general. It's crucial to remember that parameters like spacing, size, and overall pack should be taken into account while designing and using aluminium fins. Additionally, by lowering the amount of heat that is released into the environment, liquid cooled heatsinks can be utilised to lessen the environmental effect of electronic equipment. The following are some benefits of employing liquid-cooled heatsinks: ● more efficient at cooling than heatsinks that use air cooling ● can be used to enhance the functionality and dependability of electronic equipment ● can be used to lessen how harmful electrical devices are to the environment. The following are some drawbacks of employing liquid-cooled heatsinks: ● more expensive than heatsinks that are air-cooled. ● more difficult to install and keep up ● Tend to leak more frequently. Keywords — CFD, 18650,ABS ,ALUMINUM FINS ,DRIVE CYCLE MODELS,EQUIVALENT CIRCUIT MODEL.

Ageing comparison of passive battery thermal management systems: Air cooling and loop heat pipes

Flat plate Loop Heat Pipes (LHPs) have emerged as an attractive battery thermal management system (BTMS) as they allow long-distance heat transfer at no power cost due to their unique porous structure. Additionally, the flat contacting surface is suitable for end cooling in cylindrical cells due to the higher axial thermal conductivity of the jelly roll structure. Previous studies on LHP BTMS have mainly focused on the cooling performance of prismatic or pouch cells, without considering cell ageing. This study instead numerically investigates the cooling performance, the resulting current distribution, and the ageing of a 6S4P 18650 battery module equipped with LHPs BTMS, comparing the performance against a natural air convection BTMS. This study has taken various thicknesses of the heat collector plate (i.e. 0.5 mm, 1 mm, 2 mm and 3 mm) and the number of LHPs (i.e. 1 or 2) into consideration. The results indicate that utilising a single LHP in conjunction with a 2 mm thick heat collector plate emerges as the optimal configuration. This design achieves a maximum average temperature of 29.7 °C and a minimal temperature gradient of 0.02 °C under a 1C discharge condition. The proposed design also significantly enhances battery lifespan, reaching up to 310 cycles with a maximum ageing gradient of 0.005, compared to the 146 cycles and 0.04 ageing gradient observed for the module with natural air convection. This study presents the potential of LHP BTMS for future electric vehicles, demonstrating its superior effectiveness in enhancing battery performance and longevity.

Numerical investigation on liquid cooling of batteries in phase change materials

The primary focus of this study centres on managing the thermal conditions of the battery systems, addressing the various concerns related to external climatic factors on the vehicle’s performance and heat generation during the battery operation. The major objective of this study is to implement a passive thermal management system using the phase-change materials to model and control the temperature of the rechargeable batteries which are influenced mostly by critical temperature rise and external climatic influences. A numerical simulation involving a three-dimensional, single module model of a rechargeable lithium-manganese dioxide battery is involved. The control mechanism involves the application of the phase change materials within a parallelopiped structure with the battery positioned in the central location and cooled by the surrounding convective tubes through which liquid flows. The module is considered an adiabatic medium in nature. The numerical investigation involves three different C-rates for two different phase change materials RT27 and RT31, which are employed using the Finite volume method using the Ansys-Fluent. The detailed analysis of the surface temperature of the battery, liquid fraction fields and the average temperature attained by the battery module is involved using the two PCM materials.

Enhancing Electric Vehicle Battery Thermal Management using Phase Change Materials: A CFD Analysis for Improved Heat Dissipation

The adverse environmental issues and climate change has compelled world to shift to renewable energy systems. Conventional IC engines are the major contributor for air pollution which is the main cause for the global warming. Therefore, EVs (Electric Vehicle) are the future of the automotive industry. The important issues faced by EVS are battery heat generation. Hence in order to remove heat efficiently from the EV battery CFD analysis of a passive thermal management system using PCM for Li-ion batteries is studied for three different discharge rates. Compared to bare cell, the cell with passive BTMS reduces the maximum temperature rise by 2%, 2.1% and 1% at discharge rates of 1.5 C, 1.0 C and 0.5 C respectively thus implying that the BTMS adopted is effective in removing heat from the surface of the cell.

Energy- and yield-based performance evaluation of a phase change material–integrated single-span double-layered with a thermal screen greenhouse

Greenhouse technology emerged to ensure the optimum yield of the host crop —a prerequisite to achieving Sustainable Development Goals 7 and 2. To achieve this, supplemental energy is needed under extreme weather conditions at about half the operational cost. Researchers have focused and succeeded in reducing the energy demand using numerical methods with little focus on the impact of these methods on crop yield. A novel greenhouse system—phase change material–integrated single-span double-layered strawberry greenhouse with a thermal screen—is introduced herein. Furthermore, how the energy management method affects the yield of the host crop is explored. Moreover, the energy-saving potential and yield enhancement achieved by integrating PCMs and other passive thermal-management systems in a specific agricultural setting is investigated. TRNSYS 18 software is used to evaluate the effect of three passive variables on two performance indices. The passive variables are location: Daegu (DG), Seoul, and Jeju Island (JE); orientation: 90° (E-W), 45° (NE-SW), and 0° (N-S); and PCM type: “No-fill”, water, and Paraffin (ParC13–C24). The effect of thermal screen control was also studied on the localized optium configuration. Finally, economic analysis was conducted to ascertain the most sustainable configuration. The performance indices are the heating demand and strawberry yield. The results show that the location, orientation, and PCM usage inside the greenhouse greatly affect the greenhouse’s heating demand and crop yield. The configuration selected must be in such a way that the indoor nighttime temperature does not exceed 2 °C above the minimum nighttime optimum value of the host crop.

Rigorous Reliability Testing of an Encapsulated Thermal Pyrolytic Graphite (TPG) Heat Spreader for Passive Thermal Management Applications

Continued microelectronic miniaturization has resulted in higher power density, increasing the need for high performance thermal management. One possible solution for board-level thermal management is to fully encapsulate a high thermal conductivity material, such as Thermal Pyrolytic Graphite (TPG; ~1700 W/mK) in a metal (such as 6061 aluminum), producing an efficient passive heat spreader for thermal dissipation. The metal shell provides sufficient mechanical strength at a small detriment to the overall thermal conductivity. Reliability and consistent performance over time are critical for thermal management systems, especially in Defense and Aerospace applications. MIL-STD-883H provides test parameters for reliability involving exposure to mechanical shock (Method 2002.5), mechanical vibration (Method 2005.2), and thermal shock (Method 1011.9), with traditional evaluation criteria involving microelectronic device performance and/or a visual examination. For this work, the reliability of aluminum encapsulated TPG test coupons was evaluated with more demanding criteria: a visual examination, X-ray inspection, acoustic microscopy, and thermal conductivity performance testing, both before and after the previously discussed MIL-STD-883H exposures. The encapsulated coupons showed excellent robustness; the thermal conductivity properties remained constant with an average value around 965 W/mK, and the non-destructive imaging revealed excellent bond quality for the metal encapsulation, with no evidence of delamination. This more stringent evaluation criteria after MIL-STD-883H testing provides a better way to evaluate the reliability of passive thermal management systems. The study results also demonstrate the metal encapsulated TPG heat spreader as a superior thermal management solution with high performance and high reliability for demanding applications.

A numerical study on thermal control of batteries by phase change materials with liquid cooling

The thermal control of the battery system concerns about reduction in heat generation during the operation of battery and the limitations of the vehicles due to the external climatic factors. This study focuses on the attempt to control the battery from external climatic factors and temperature peaks during its operation by the principle of passive thermal management system using phase-change material. A numerical investigation of a three-dimensional model for a cylindrical lithium-polymer battery as a single module is done. The thermal control is realized by a phase-change material for a battery placed inside a parallelopiped and cooled by convective tubes placed at constant temperature and the surface of the module is considered as adiabatic. The governing equations are solved using the Finite Volume method using Ansys-Fluent. The investigation involves 3 different C-rates for two different phase change materials. The results analyse the maximum temperature, temperature distribution and liquid fraction fields for the different cases. The obtained results indicated that for the two different PCM materials namely RT25HC and RT35HC used for the cooling of the batteries the maximum temperature reached by battery and the average temperature of the PCM materials used was observed to be higher in RT35HC.

Passive and hybrid battery thermal management system by cooling flow control, employing nano-PCM, fins, and metal foam

The performance and safety of lithium-ion batteries, especially in electric and hybrid vehicles, rely on efficient thermal management. Thus, researchers have shown interest in investigating passive, active, and hybrid approaches for battery thermal management (BTM). This study presents a novel hybrid design for a BTM system involving three cylindrical 18650 batteries encased in phase change material (PCM). The research evaluates the impact of fluid flow velocity and direction in the channels on battery temperature, seeking temperature reduction and uniformity. To optimize the proposed system performance, three methods for improving heat transfer in the PCM have been explored and compared, including using nanoparticles (3 %–9 % volume percentage), employing fins (2 and 4 fins), and implementing metal foam (porosity ranging from 85 % to 95 %). Results indicate that, for a 4C discharge rate, incorporating 9 % nanoparticles and 4 fins in the hybrid mode reduces peak temperature by 5.18 and 10.36 K, respectively, compared to the hybrid modes without nanoparticles and fins. These reductions are 10.41 and 9.20 K superior to the corresponding passive modes diminutions, respectively. Additionally, using copper foam with 90 % porosity reduces battery peak temperature by 12.57 K at a 3C discharge rate, highlighting the effectiveness of this method.

Steady and transient sensitivity investigations on a passive battery thermal management system coupling with phase change materials and heat pipes: Full numerical modeling and orthogonal tests

For safety reasons, the temperature distribution of the battery pack should be kept within a reasonable range. Therefore, in the present research, a passive battery thermal management system (BTMS) coupling with phase change material (PCM) and heat pipes (HP) was proposed. Full CFD (Computational Fluid Dynamics) models validated well by the experimental results were adopted for this research. Firstly, the sensitivity of parameters such as PCM type, PCM thickness and ambient temperature on the thermal performance of BTMS was obtained by orthogonal tests. Numerical results show that the greatest influence on the maximum temperature is the ambient temperature. In the variance analysis showed that the PCM thickness has a significant effect on decay the battery temperature difference. Furthermore, operational range and variance analysis confirmed the optimal BTMS, i.e., with PCM3 thickness of 3 mm and ambient temperature of 30 °C. Subsequently, transient modeling and analysis of the battery discharge process were carried out. Unsteady results showed that the maximum temperature of the battery was reduced from 68.90 °C to 43.19 °C, and simultaneously, the maximum temperature difference dropped from 16.58 °C to 3.66 °C. In the process of battery discharge, PCM was properly adjusted regarding of its thickness; whereas, its melting temperature should be kept approaching to the ambient temperature, which was beneficial to the operational safety of the battery. In addition, temperature distribution of the battery has a linear relationship to the ambient temperature; when every 5 °C increase was observed in ambient temperature, the maximum temperature of the battery was boosted by 2.3 °C and the temperature difference was reduced by 1.2 °C, separately. Present research, straightforwardly maintaining the temperature distribution of the power battery in a safe and efficient range, could be significant for improving energy utilization and reducing extra energy consumption of the power battery, simultaneously.

Thermal performance enhancement of a passive battery thermal management system based on phase change material using cold air passageways for lithium batteries

The hybrid battery thermal management system (BTMS), the combination of an active thermal management system (TMS) and a passive TMS based on phase change material (PCM) will keep the battery temperature within a suitable range while possessing a greater cooling effect in comparison with a passive TMS and using less energy than an active TMS. Throughout this research, the structure role of the active TMS that comprises an air cooling system is investigated. To this end, nine case studies possessing three different cooling duct structures and three different cold air stream pressure differences are simulated and studied. The outcomes indicate that the rising of the temperature, even for the worst-case scenario, is safe, acceptable, and smooth-enough for thermal management considerations. The maximum temperature of the cells never exceeded 314 K, showing the perfect capability of proposed hybrid BTMS. Furthermore, one can notice that the more powerful the inlet air stream or the more length of cooling ducts through the PCM volume, the lower battery surface temperature is experienced. Additionally, in all simulated cases, the maximum temperature difference of the cells within the battery module does not go beyond 1.6 °C, demonstrating the excellent aptitude of proposed hybrid BTMS in creating uniform temperature distribution within the battery pack. On the other hand, it is concluded that the more powerful the inlet air stream gets or the more length of cooling ducts through the PCM volume is applied, the larger maximum temperature gradient is observed.

High emissive contrast of adaptive, thin-film, tungsten-doped VO2 composites

There is a significant interest in developing advanced materials technologies that will reduce the consumption of fossil fuel resources. One efficient way of reducing energy consumption for heating and cooling applications is the development of a passive and adaptive thermal management system that radiates heat at high temperatures while providing insulation under cooler conditions. Vanadium dioxide (VO2) is a candidate material for this type of adaptive behavior since it transitions from a low temperature reflective state to a high temperature emissive state at 68 °C when deposited upon a dielectric-coated ground plane. Additionally, by doping VO2 with high valence tungsten (W6+), the transition temperature can be reduced to values that are close to room temperature (22 °C). In this Letter, W6+-doped VO2 multilayer composites are designed to utilize thin film interference in order to maximize the infrared (IR) emission contrast between the hot and cold states of VO2 while also reducing the transition temperature. Through careful engineering of the thickness and doping of the VO2 layer within the multilayer film, a 50% emissive contrast was maintained across the 8–13 μm spectral region, while the transition temperature was reduced from 68 °C in the undoped film to 29 °C in the 1.7 at. % W6+.

Multifunctional flexible composite phase change material with high anti-leakage and thermal conductivity performances for battery thermal management

Composite phase change material (CPCM) as passive battery thermal management system (BTMS) still confronted many challenges such as easy leakage, high rigid and low thermal conductivity. In this study, a multifunction flexible CPCM with high anti-leakage and thermal conductivity performances has been proposed which is utilized the polymerizing and crosslinking reaction with polyethylene glycol and hexamethylene diisocyanate to address the leakage of CPCM in essence. The results revealed that the CPCM exhibited excellent antileakage and elastic performance. Especially, the thermal conductivity of CPCM is obviously improved by 2.8 times owing to the synergistic effect of 3 wt% aluminum nitride and 2 wt% carbon nanotubes. Besides, the maximum temperature of the battery module with multifunction flexible CPCM can be controlled below 45 °C even at 1.5C discharge rate, and the corresponding temperature difference is maintained within 4.3 °C. With these outstanding properties, the multifunctional flexible PEAC can provide an efficient solution to improve the thermal safety of battery packs in applications, which will significantly promote the development of EVs.

Experimental optimization of various heat sinks using passive thermal management system

Organic phase change materials are extensively researched for passive cooling of electronic components due to the high heat of fusion, however, owing to the issue of thermal conductivity, it is difficult to improve the thermal performance of electronic components. However, the effective thermal performance of modern electronic devices is becoming popular due to thermal constraints of the circuit's non-uniform temperature distribution and high heating power generation. Thus, nanomaterials incorporated into phase change materials (PCMs) to improve thermal conductivity, which aids in heat removal and sustains significant heat sink operational performance for extended periods of time. In current research work, at heating powers of (10–30 W), the thermal performance outcome of three heat sink -configurations such as unfinned heat sink, circular pin-finned heat sink and metallic foam integrated heat sink were investigated with several alumina nanomaterials mass concentrations (0.15, 0.20 and 0.25 wt%) incorporated in phase change materials (for example RT-70HC). All three heat sinks revealed lower base temperature with the addition of alumina NePCM (αRT-70HC) phase change materials in their internal cavity compared to the empty unfinned heat sink. The findings showed good performance of metallic foam integrated heat sink in lowering the temperature & increasing safe functional time at two distinct temperatures. The largest decrease in temperature was found to be 35.76% and the largest growth in maximum functional time was 400% for metallic foam integrated heat sink. Therefore, using alumina nanomaterials in phase change material is recommended to optimize the thermal performance of the passive cooling techniques.

Experimental study on 3D printed heat pipes with hybrid screen–groove combined capillary wick structure

The integration of heat pipes as a passive thermal management system for nuclear reactors has been proposed as it provides the advantages of compact design, reliability, efficient heat transfer performance, and enhanced safety. Applying the heat pipe to a nuclear reactor without collision between systems and achieving efficient long-distance heat transfer requires the manufacturing of heat pipes with a high degree of freedom. Using three-dimensional (3D)-printing technology can be a solution for fabricating complex or bent capillary wick heat pipes into an integrated geometry. The study involves the production of a heat pipe using metal 3D-printing technology and an experimental study conducted for thermal performance evaluation. The heat pipe includes a combination of a screen-groove wick in the evaporator section, a groove wick in the adiabatic and condenser sections, and a bent wick structure in the middle. By using 3D printing technology, it is possible to create a heat pipe that has a complex wick design, a consistent porous structure and remains undistorted during the manufacturing process. The surface roughness of the 3D-printed heat pipe was 17 to 1700 times higher than the commercial stainless-steel pipe, which has the benefit for enhance capillary performance. The experimental results showed that the 3D-printed heat pipe can achieve high effective thermal conductivity up to 25.7 kW/m-K and showed 24.2% lower thermal resistance compared to the conventionally manufactured heat pipe. Furthermore, it can be successfully operated at various inclination angles.

Optimal design of lithium ion battery thermal management systems based on phase change material at high current and high environmental temperature

The market of electric storage systems is widely dominated by Lithium ion batteries, whose peculiarity is the need for a thermal management system, whose proper design is complicated by the interaction. among different design and operating parameters. A specific methodology for carrying out the task is still lacking. In this context, the present paper proposes a systematic framework for the design of passive and hybrid thermal management systems (TMSs) of Li-ion batteries. Thermal tests were carried out on Lithium-Titanate-Oxide cells under realistic operating conditions in a controlled environment to characterize the electrical and thermal behaviour. A thermofluid dynamics model of the battery was implemented in COMSOL Multiphysics. The experimentally validated model was used to evaluate the influence of different design and operating parameters (ambient temperature, charge/discharge current, phase change material thickness and melting temperature) using the Taguchi method (orthogonal arrays), and discussing inter-related effects of the studied parameters via interaction plots. Air temperature (45 °C) and/or discharge current (69–92 A) were identified as critical operating conditions beyond which thermal runaway issues occur. Starting from the optimal design conditions for a passive TMS, the same methodology was used to assess a hybrid PCM-liquid cooling system as an alternative configuration. The results indicate that, compared to the baseline case of natural cooling, the optimal designs of standalone PCM and hybrid cooling system led to a reduction in maximum cell temperature of 11 and 22 °C, respectively, showing the high potential of these TMSs.

Study on the temperature control performance of photovoltaic module by a novel phase change material/heat pipe coupled thermal management system

High photovoltaic (PV) module temperature leads to the degradation of electrical efficiency, and passive PV thermal management systems, such as phase change materials (PCMs) and heat pipes (HPs), have been widely adopted to address this challenge. Due to the low thermal conductivity of PCM and the limited heat exchange capacity in the HP condensation section, this paper proposes a novel configuration for a PV thermal management system utilizing a phase change material/heat pipe coupled module (PV-PCM/HP). The experimental results showed that the performance of the coupled PCM/HP system was superior to that of the single system. A numerical model was developed to simulate and analyze the temperature variation and coupled heat transfer characteristics of the PV-PCM/HP system. The main components of heat transfer gradually change from PCM (PCM-dominated) to HP (HP-dominated), and PCM even plays a negative role during the solidification stage, which means that the coupled thermal management depends on HP only. Four design parameters (the number of HPs, PCM thermal conductivity, PCM phase change temperature, and PCM thickness) of the PV-PCM/HP system are discussed to investigate the effects on the performance of the PV-PCM/HP thermal management system. This shows that the increase in the number of heat pipes and PCM thickness can effectively improve the performance, but they should be determined according to technical and economic analysis. When the PCM thermal conductivity is >2.7 W/(m·K), it has little effect on thermal management performance under the conditions described in this paper. The value of the PCM phase change temperature should be determined according to actual weather conditions, and the purpose is to make the PCM melting period coincide with the period of higher solar radiation and lower phase change temperatures.

Passive battery thermal management system for an unmanned aerial vehicle using a tetrahedral lattice porous plate

Lithium-ion batteries (LIB) are the main energy source for unmanned aircraft vehicles (UAVs) and drones. A drone operates at various ambient temperatures, depending on its flight characteristics. For optimal performance, this requires the application of a passive battery thermal management system (BTMS) that does not require additional equipment due to drone weight limitations. This study proposes applying a multifunctional tetrahedral lattice porous plate (TLPP) to analyze the performance of a passive BTMS using aspirated airflow through a drone flight mode. A battery cell constant-current discharge experiment is conducted to derive the equivalent internal resistance of the battery cells for the numerical simulation of battery heat generation. The performance of a passive BTMS with a TLPP channel, including part of the freestream through a series of drone modes, is analyzed using experiments and numerical simulations at the battery cell and module levels. The main conclusion of this study was that in a numerical simulation of takeoff and landing in drone operation mode, the maximum temperature, and deviation reduction rates were 22 % and 4 9%, respectively. Additionally, the maximum temperature and deviation from the TLPP application under conditions in which some freestreams were aspirated during the drone's forward flight were reduced by 35 % and 76 %, respectively. It is confirmed that the maximum temperature and deviation on the battery surface are significantly reduced due to the application of TLPP on a bare battery. Therefore, passive BTMS with TLPP can provide effective multifunctionality for the thermal management of drone batteries.