Thermal Insulation Conditions Research Articles

Experimental study on snow melting and deicing of carbon fiber heating roads considering thermal insulation conditions

The electrothermal method for snow melting and deicing in road engineering provides efficient deicing. To improve the ice melting efficiency of carbon fiber heating cables, employing extruded polystyrene foam board (XPS)、polyethylene foam cotton (PEF) as insulation materials under the carbon fiber heating wire could reduce heat transfer to the lower layers of the road structure. Road model tests were conducted under various conditions to analyze how different heat insulation conditions、environmental temperatures affect road snow melting and ice melting. The results indicate that the placement of the heat insulation layer significantly affects the temperature fluctuation range between its upper and lower layers.The ice melting rate increases by 25∼50 % compared to pavement structures with no heat insulation layer. When heat insulation material is incorporated into the road structure layer, under preheated conditions, snow with a thickness of 0.2 cm on the surface of the plate heat insulation model can completely melt within 2.5 h, reducing the effective ice-melting time by 40∼51.7 %. A comparison of the thermal performance of the two insulation materials under various conditions reveals that the XPS plate is more suitable as an insulation layer compared to other materials.

Heat flow density measurement during non-destructive testing

The object of the study is the development of a device capable of accurately and reliably measuring heat flux density in various environments. The development of a heat flux density meter designed for non-destructive analysis of thermal processes in various fields of application is presented. The developed device is intended for evaluating the thermal insulation condition of underground pipelines. The functionality of the heat flow device relies on comparing standard temperature values with experimental ones measured on the soil surface. To ensure accurate and reliable measurement of heat flux density, the basis is a thermoelectric battery converter, which uses the auxiliary wall method. The heat flow density measuring device is constructed in the shape of a restricted cylinder, with one base serving as the working surface, while the second base establishes thermal contact with the body at ambient temperature. Embedded heaters enable the generation of heat flow through the thermoelectric sensor in directions perpendicular to its base. For calibrating the heat flux device, experiments were conducted using a standard copper-constantan calibration table. Temperature increments were determined from thermo electromotive force, and tests were performed on an existing heating network. The conducted measurements validate the fundamental feasibility of employing the proposed device for implementing the non-destructive thermal testing method on underground heating mains. The results of the experiment can be used not only for research, but also for monitoring and regulating processes in various fields of science and technology. The developed heat flux meter promises a significant contribution to the development of modern methods for analyzing thermal processes. The dimensions of the thermoelectric battery converter are also determined and the coefficient (kq) should be in the range from 4.0 to 12.0 W/(m2⋅mV), and the electrical resistance should be in the range of 12–20 kOhm

Simulation analysis of thermal insulation performance of diesel engine piston based on PEO and La2Zr2O7 thermal barrier coating

In this research, we explored the application of ‘thermal swing’ thermal barrier coatings (TBCs) in diesel engines, aiming to surpass the performance of conventional TBCs. Traditional TBCs often suffer from limitations like consistently high surface temperatures and a delayed response to sudden variations in cylinder temperatures, which adversely impact engine efficiency. To overcome these challenges, plasma electrolytic oxidation (PEO) technology was employed to engineer TBCs with the sought-after ‘thermal swing’ feature. Comparative simulations were conducted to assess the thermal characteristics of PEO coatings on pistons, in contrast to standard La2Zr2O7 coatings. The steady-state thermal analysis revealed that PEO coatings maintained a lower peak temperature compared to La2Zr2O7 coatings under similar thermal insulation conditions, indicating a superior ability of the PEO coatings in heat dissipation and in sustaining lower surface temperatures.In the transient thermal analysis, focusing on temporal temperature variations, the PEO coatings exhibited a markedly quicker and more robust response to cylinder temperature fluctuations. This indicates that PEO coatings are highly effective in adapting swiftly to temperature changes, thereby contributing to enhanced engine performance. Additionally, the PEO coating demonstrated a notable reduction in the end temperature (TE), which is crucial for mitigating the heating effect on intake gas, in comparison to La2Zr2O7 coatings with equivalent thermal insulation properties. However, it was observed that this advantage significantly decreased when the PEO coating thickness surpassed 0.3 mm. Drawing from these observations, it is concluded that PEO coatings hold several thermal advantages over La2Zr2O7 coatings, particularly in terms of thermal load management and responsiveness to in-cylinder temperature shifts. These benefits are most pronounced when the PEO coating maintains a thickness below 0.3 mm.

Multi-network PVA/SA aerogel fiber: Unveiling superior mechanical, thermal insulation, and extreme condition stability

Aerogels are highly sought-after in thermal insulation textiles due to their exceptional porosity and low density. However, Current research on aerogels mainly centers on their fixed two- and three-dimensional structures, lacking design flexibility, which significantly restricts their practicality. In contrast, one-dimensional aerogel fibers, while offering design flexibility, face complex fabrication, challenges in continuous molding, and pore collapse issues. In this study, utilizing polyvinyl alcohol (PVA) and sodium alginate (SA) as raw materials, a cost-effective wet spinning, freeze-thaw cycling, and freeze-drying technique were employed to continuously produce multi-functional PVA/SA aerogel fibers with a stable network pore structure through the design of a multi-crosslinked interlocking network structure. The optimal preparation process for the aerogel fibers was explored and characterized. The resulting aerogel fibers exhibited a stable hierarchical pore structure at the microscale, featuring large pores, nested mesopores, and micropores. These fibers possessed a high specific surface area (115.88 m²/g), high porosity (92.42 %), low density (0.0632 g/cm³), low thermal conductivity (0.0378 W/(m·K)), and flame resistance (LOI: 26.8 %). Furthermore, their stable internal network scaffold structure endowed them with outstanding mechanical properties (3.6 cN/tex) and stability in extreme environments. These composite aerogel fibers offer great potential for high-performance thermal insulation textiles and products.

Thermal effects associated with the crack of high-temperature superconducting magnetic levitation system

Based on the magnetic flux pinning characteristics of the non-ideal type II superconductor YBa2Cu3O7−x, the high-temperature superconducting magnetic levitation system has the advantages of self-stability in levitation and low energy consumption. Thermal stress, electromagnetic force, and other mechanical stress may cause the micro-cracks to expand and eventually lead to fractures in the application of superconducting materials, significantly affecting the superconductor’s ability to transmit current. The superconducting magnetic levitation system with low damping is prone to nonlinear vibration of large amplitude under external interference, which affects the system’s regular operation. Due to the limitations of experimental conditions, it is difficult to analyze complex physical phenomena with cracks and obtain the distribution characteristics of electromagnetic, heat, and force inside the superconductor in the nonlinear vibration process, as theoretical modeling can compensate for this deficiency. In this paper, we study the fracture behavior of the YBa2Cu3O7−x bulk superconductor under nonlinear vibration based on the flux creep and flow models. The temperature of the superconductor in the nonlinear vibration of the superconducting levitation system is calculated with center cracks. The flux flow phenomenon in the bulk superconductor for various cracks under the bifurcation vibration is presented. The results show that the temperature of the superconductor will dramatically rise in nonlinear vibration under thermal insulation conditions, and the distribution position is affected by the cracks. For the 15 and 12 mm center cracks, a large amount of heat is generated around the crack and causes the temperature to rise above the critical temperature.

Experimental study on the flexible peak shaving with pulverized coal self-preheating technology under load variability

The integration of renewable energy sources into power grids has led to power fluctuations, necessitating coal-fired power units to provide flexible peak shaving. The pulverized coal self-preheating technology can potentially provide broad-load regulation and rapidly respond to load changes. In this study, the impact of the self-preheating technology on fuel preheating modification, combustion characteristics, and NOx emissions are investigated. Load-stabilization bases are proposed based on preheating temperature, preheated coal gas composition, combustion temperature, and flue gas emissions. Load change rates are calculated using these bases to character the load response. The results demonstrate that the preheated fuel has similar properties as the highly reactive gaseous fuel and exhibits excellent ignition and combustion performances at 25 % load. Preheating treatment improves combustion efficiency, and burnout ratio and reduces NOx emissions. The NOx concentration approaches the ultra-low emission standard at 50 % load. Four load-stabilization bases, covering the preheating and combustion sides, comprehensively characterize the load response performance. The rates based on preheating indicators and combustion indicators maximize to 3.30 %/minute and 2.71 %/minute, respectively. The load change rate in the ramp-up phase is higher than that in the ramp-down phase, which is related to the effective internal heat storage carrier and external thermal insulation conditions. The driving force formed by high load step ranges and the deviation from the full load capacity are conducive to increasing the load change rates.

Research on the Improvement of Lithium-Ion Battery Performance at Low Temperatures Based on Electromagnetic Induction Heating Technology

As the major power source for electric vehicles (EVs), lithium-ion batteries (LiBs) suffer from the degradation of technical performance and safety at low temperatures, which restricts the popularization of EVs in frigid regions. Thus, this study developed an extremely fast electromagnetic induction heating system in order to improve the poor performance of LiBs in cold weather. An electrochemical–thermal coupling model (ETCM), validated against the experimental results of charge and discharge, which successfully predicted LiB voltage, temperature, and other physical characteristics at various ambient temperatures, was established in COMSOL Multiphysics 6.0 as a development tool for evaluating the heating effect of the system. When the copper coil is subjected to a SAC (sinusoidal alternating current) of 8 A and 50 Hz, the LiB can be heated from 243.15 to 293.15 K within 6 min with an instantaneous temperature increase rate of 0.263 K/s and a homogeneous temperature distribution. The results of the capacity calibration, cyclable lithium detection, and HPPC simulation show that the heating method can visibly increase the Li+ concentration inside the active particle, and there was only a tiny concentration gradient on the surface of the particle. In addition, the internal resistance was approximately a quarter of that without heating; therefore, both the discharge energy and specific power boost were two times higher than the original level. Compared to the normal charge–discharge cycles at 293.15 K, the capacity retention of the LiB only decreased by 0.23% after 60 consecutive heating cycles, so the heating method can balance the temperature rise, work capacity, and LiB health. Furthermore, the improvements in the thermal insulation condition and material thermal conductivity are two feasible ways to optimize the temperature-increase effect.

A multi-zone thermodynamic model for predicting LNG ageing in large cryogenic tanks

During the storage and transportation of liquefied natural gas (LNG), generation of boiloff gas (BOG) and change in the LNG composition, also known as LNG aging, are inevitable. Thus, a thermodynamic model that can accurately predict LNG aging during long-term operation is critical. This study presents a novel aging model, in which the LNG tank is divided into five zones: the vapor phase region, thermal stratification, bulk liquid region, boundary layer, and surrounding thermal insulation region. The heat and mass transport into different regions were calculated separately, and the thermal conductivity of the solid walls was considered as a function of temperature. Following model validation, simulations were performed for various thermal insulation conditions, ambient temperatures, and initial liquid compositions. From the results, the errors of the pressure, BOG rate and total heat flux could be approximated to 17, 7, and 14% respectively, for the previous models omitting the variation of thermal conductivity with temperature. As the initial methane fraction increased (i.e., N fraction decreases), the BOG rate decreased at the initial stage, while the BOG rate became less sensitive with the initial LNG composition as evaporation proceeded. Such an effect is determined by the variation in the latent heat of vaporization and total heat loss. This study can provide guidance for the design and operation of LNG storage tanks.

Evaluation of epoxy-based coating degradation under thermal insulation at elevated temperatures on different steel substrates

Corrosion under insulation (CUI) remains one of the most critical issues in the petrochemical industry. In a typical CUI system, protective coatings (organic or metallic) are used primarily as the last barrier to prevent the rapid corrosion of the metallic substrate. However, organic coatings exposed to high operating temperatures and thermal cycling conditions are susceptible to failure and thus require coating performance evaluations under representative thermal insulation conditions. This study presents experimental designs to investigate the degradation of an organic polyamine-cured epoxy coating under accelerated laboratory test conditions. Additionally, a systematic CUI evaluation protocol for high-temperature organic coating performance is presented. The method involved specially designed apparatus to simulate CUI systems and characterisation techniques, such as visual inspection, adhesion test, peel-off test, scanning electron microscopy, electrochemical impedance spectroscopy, and chemical analysis using Fourier-transform infrared spectroscopy, and differential scanning calorimetry. The results showed that polyamine-based epoxy coating experienced thermal degradation starting at temperatures above 130 °C under mineral wool insulation in accelerated and cyclic CUI tests. Chemical degradation was the primary mode of degradation, with the formation of carbonyl functional groups and increased glass transition temperature observed at higher exposure temperatures. The proposed combination of electrochemical, spectroscopic, mechanical, and microscopy techniques allows quantifying coating performance under insulation and subsequently provides insights into predicting coatings' service lifetime.

Optimization design research of insulation thickness of exterior wall based on the orientation difference of solar radiation intensity

Different from the traditional isotropic insulation design which aims at reducing building heat loss, a new anisotropic insulation design method which fully considers the orientation difference of solar irradiation is proposed for the purpose of reducing indoor radiant thermal discomfort. Based on the principle of equal heat flux intensity of the envelope, a simplified calculation method of the insulation thickness in each orientation is established. The relationship between each orientation insulation thickness can be simplified as a linear relationship. The influence characteristics between the factors like exterior surface, brick wall thickness, brick and insulation material and the orientation differential insulation thickness are obtained. Six typical cities in China are selected in combination with solar energy resource zones and building thermal divisions, and the insulation thickness of building envelope in each region is calculated. The results show that the orientation differential insulation design mode is suitable for solar energy resource zone I and zone II. Taking Lhasa as an example, compared with isotropic thermal insulation conditions, the material cost of thermal insulation layer under orientation differential insulation conditions is reduced by 24.6%, and the average heating energy consumption increases only by 6.1%. When the insulation material is the same, the average heating energy consumption can be reduced by 9.0%. The results can provide a reliable basis for the application of orientation differential insulation technology in rich areas of solar energy resource.

Физико-химические и термические превращения газонаполненной полимерной теплоизоляции естественного старения

Introduction. In the process of operation, various materials are subjected to prolonged exposure to environmental factors, which can lead to irreversible physical and chemical changes that affect not only their service life, but also fire safety. In this regard, the study of the influence of natural ageing on the features of the combustion process, fire hazard characteristics of thermal insulation materials is relevant. Aims and objectives. The aim of the work is to evaluate the physicochemical and thermal transformations of polymer gas-filled thermal insulation (expanded polystyrene foam) of long-term natural ageing. Methods. A set of physicochemical methods, namely X-ray phase analysis, infrared spectroscopy and thermal analysis methods (TG, DTG, DSC) were used to study the physicochemical nature and thermal stability of naturally aged polystyrene foam. Results and discussion. In the work the technical condition of polymer thermal insulation was assessed on the objects: cinema "Udarnik" (Russia, Moscow), 1927-1930 year of construction and a residential building (Tajikistan, Vahdat), 2014 year of construction. The method of X-ray phase analysis for polystyrene foam of natural ageing revealed a decrease in crystallinity. The change in the phase state of polymer thermal insulation indicates the thermal fluctuation nature of the processes associated with its natural aging and leading to a change in the ordering of the arrangement of individual macromolecular sites of aromatic hydrocarbon. At the same time, under the conditions of natural ageing there is a decrease in the apparent density of polystyrene foam by 20-41 %. By method of infrared spectroscopy the greatest changes are established in areas of characteristic absorption bands 3057...2846 cm-1, and also 1500...1450 cm-1, that testifies to destabilisation of hydrocarbon chains of macromolecules of polystyrene foam of natural ageing. The character of thermo-destructive transformations is established for the investigated samples, the tendency of expansion of the main section (335...470 °С) in comparison with the samples without natural ageing (360...450 °С) is revealed. The identified features of physicochemical and thermal transformations of naturally aged polystyrene foam can lead to changes in the intensity of the combustion process and heat release. Conclusion. According to the results of the study it is established that in the process of natural ageing in gas-filled polymers irreversible physical and chemical changes occur under the influence of environmental factors. Deterioration of the technical condition of polymer thermal insulation during its operation can lead to changes in the characteristics of fire hazard, features of its combustion and heat release when exposed to fire. Keywords: thermal insulation; polymers; polystyrene foam; fire hazard; service life; natural ageing.

Thermal runaway propagation characteristics and preventing strategies under dynamic thermal transfer conditions for lithium-ion battery modules

In recent years, frequent safety accidents resulting from thermal runaway propagation (TRP) bring concern on the further application of lithium-ion batteries (LIBs). TRP is a complex, interrelated and systematic process, the characteristics of which need to be investigated under dynamic variation of thermal insulation and heat dissipation conditions. Here, experiments and simulations are conducted to investigate the influence of dynamic heat conductivity (i.e. λ) and heat convection coefficient (i.e. h) on the TRP characteristics and prevention effectiveness, covering two core TRP suppression strategies: thermal insulation among adjacent batteries and heat exchange with the cooling system. It is revealed that the TRP mode can be divided into two types according to the variation of λ and h. In addition, through the heat flow analysis, it is found that the synergistic effect of thermal insulation and heat dissipation of battery module is the key to inhibit TRP. Therefore, we innovatively propose the three-dimensional credibility intervals: the functional relationship between λ and h that is required to completely block TRP or to make TRP time exceed 300 s, which provide a pragmatic guidance for different types of modules safety design in practical application.

Optimum Energy Management for Air Conditioners in IoT-Enabled Smart Home.

This paper addresses the optimal pre-cooling problem for air conditioners (AC) used in Internet of Things (IoT)-enabled smart homes while ensuring that user-defined thermal comfort can be achieved. The proposed strategy utilises renewable energy generation periods and moves some of the air conditioning loads to these periods to reduce the electricity demand. In particular, we propose a multi-stage approach which maximises the utilisation of renewable energy at the first stage to satisfy air conditioning loads, and then schedules residual energy consumption of these loads to low price periods at the second stage. The proposed approach is investigated for the temperature and renewable generation data of NSW, Australia, over the period 2012–2013. It is shown that the approach developed can significantly reduce the energy consumption and cost associated with AC operation for nearly all days in summer when cooling is required. Specifically, the proposed approach was found to achieve a 24% cost saving in comparison to the no pre-cooling case for the highest average temperature day in January, 2013. The analysis also demonstrated that the proposed scheme performed better when the thermal insulation levels in the smart home are higher. However, the optimal pre-cooling scheme can still achieve reduced energy costs under lower thermal insulation conditions compared to the no pre-cooling case.

Influencing factors and experimental study on electrothermal high temperature field of the outburst coal in China

In this study, we proposed a method to solve the problems of low permeability of the outburst coal seams and gas extraction in China. We used heating cables to heat outburst coal seams and increase the gas desorption capacity of coal seams to prevent outbursts. An experimental cement tank was constructed to investigate the influence of the heating temperature, cable layout and thermal insulation conditions in the cement tank on the electrothermal high-temperature field characteristics of the outburst coal sample. The following results were obtained: The effective heating radius of the heating cable was 800 mm ≤ R < 1,000 mm. As the heating time increased, the temperature of the coal sample in the cement tank first increased rapidly and then became stabilized. The same heating time, The coal sample temperature of the cement tank in the third experimental scheme is the highest When the heating temperature was 300°C, the maximum coal sample temperature was 107°C. The stable temperature of the coal sample in the cement tank was considerably higher under thermal insulation conditions than under no-thermal insulation conditions.

Optimization of a Combination of Thermal Insulation and Cool Roof for the Refurbishment of Social Housing in Southern Spain

Social housing built in the middle of the last century in Spain suffers from poor thermal insulation conditions that cause situations of discomfort and energy poverty. For this reason, the energetic refurbishment of the envelope of this social building stock is necessary to overcome these situations and reduce energy consumption aimed at achieving interior comfort for its occupants. The goal of this work is to optimize a constructive solution that combines cool roof techniques with the use of thermal insulation applied to the refurbishment of the roof of buildings belonging to a quarter of social housing in Seville, Spain. The optimization analysis is based on the computation of the energy performance of the roofs when the energy retrofitting measure is applied, considering a variety of combinations of solar reflective coatings and insulation layer thickness, performing a dynamic analysis that accounts for the aging effect of the cool coats on the monthly roof energy performance and on the economic balance for the whole life cycle (LC) span. Economic and energy optimization analysis show that a suitable combination of cool roof emissivity and insulation layer thickness produces significant savings in the operational energy and in the economic profitability of the proposed retrofitting measure: the optimum combination obtained provides for the entire life cycle timespan an energy savings of 5.71 GJ/m2 and a cost savings equivalent to the 63.1% of the total costs when compared to the non-refurbished roof. The application of a time-dependent pattern for the changes on time produced by the aging effect on the cool roof emissivity, and its effects on the optimization of the combination of cool roof and insulation layer, can be considered novel in literature, both from an energy and an economic point of view.

Boussinesq Functions of the 3d Problems of Thermoelasticity for Half Spaces with a Heat Source or a Thermal Dipole

In the case of action of a stationary heat source or a thermal dipole, we construct the Boussinesq functions of the problems of thermoelasticity for a semiinfinite space with free, rigidly, smoothly, or flexibly fixed boundary kept either at zero temperature or under the conditions of thermal insulation. The Green functions obtained by using the Boussinesq functions can be used to determine the thermoelastic state of the half space caused either by heat generation in a domain parallel to the boundary or by the perturbation of a given heat flux by a heat-proof thin inclusion parallel to the boundary of half space.

ОЦІНЮВАННЯ ТЕПЛОІЗОЛЯЦІЙНИХ ПОКАЗНИКІВ ОГОРОДЖУВАЛЬНИХ КОНСТРУКЦІЙ БУДІВЕЛЬ ЛІНГВІСТИЧНИМИ ЗМІННИМИ

The classification of the factors influencing decision-making at an estimation of thermal conductivity of a heat-insulating cover of the building is offered. The relationship between the parameters of the thermal state of the thermal insulation of buildings and its energy efficiency is presented in the form of a logical conclusion tree. The logical inference tree at the system level characterizes the ratio of parameters that affect thermal conductivity. To create a mathematical model for expert assessment of the technical condition of the thermal insulation of the building, it is advisable to use the apparatus of fuzzy logic and fuzzy set theory. The formalization of quantitative and qualitative factors influencing the thermal efficiency of the building insulation shell has been carried out. When assessing the technical condition of the thermal insulation of the building (energy efficiency), quantitative and qualitative factors of influence are expressed through linguistic variables. Estimation of levels of linguistic variables is represented by term sets. Thermal conductivity as a factor in the thermal insulation of a building is related to the normative classification of energy efficiency of buildings in force in Ukraine.

Supercritical convective flows of melt water in an open horizontal rectangular cavity with a prescribed vertical heat flux

The influence of the intensity of heating, expressed by the Grashof number, on supercritical regimes of thermal convection of melt water in a horizontal rectangular cavity with an aspect ratio of two is investigated. On the lateral solid boundaries, the thermal insulation conditions are satisfied, and a constant vertical heat flux is set on the lower solid and upper free horizontal and non-deformable edges. Under conditions when the cavity-average temperature is close to the temperature of water density inversion in the cavity, a state of mechanical equilibrium is possible, when a stably stratified layer is located on top of an unstable stratified layer. For two cases of the position of the horizontal boundary between these layers, the structure of stationary planar supercritical thermal convection is investigated. The calculations were carried out by the finite-difference method on a square grid with 128 nodes along the horizontal coordinate and 64 along the vertical one. Calculations have shown that, with an equal thickness of unstable and stably stratified layers, supercritical convection in the region up to about six supercriticalities has a two-cell structure in the horizontal direction with two (large at the bottom and weaker at the top) vortices in each of the cells. With an increase in supercriticality, this two-cell structure turns into a four-cell structure in a hysteresis manner. For the case when the thickness of the stably stratified layer is three times less than the thickness of the unstable stratified layer, the supercritical convective flow has the general form of a single-vortex cell elongated horizontally. With an increase in the Grashof number up to about a hundredfold supercriticality, it remains generally single-vortex and does not experience bifurcations.

Fracture Mechanics Analysis of Thermoelectric Materials With Equilateral Triangle Holes

The fracture mechanics for thermoelectric materials with equilateral triangle holes subjected to uniform electric current densities and uniform energy fluxes at infinity was studied by means of the complex variable method. The analytic expressions of temperature fields and stress fields were obtained under the boundary conditions of electric insulation and thermal insulation. Effects of the triangle size, the applied electric current density and the energy flux on the thermoelectric material were analyzed. The results show that, the variations of the current density and the triangle size have obvious influences on the annular energy flux, the annular stress and the annular heat flux.

Simulation study of local thermal runaway of 18650 lithium battery module under multi-point thermal trigger

The thermal runaway of lithium power battery is the key problem of battery safety, according to the standard SAE J2464–2009 single point heating key position, the proposed multi-point trigger based thermal runaway of lithium power battery module simulation method and battery module thermal runaway battery monomer ratio PN, thermal runaway trigger time tn two indicators, the thermal runaway rule of 18650 lithium power battery module under different trigger position, trigger points. The results show that considering the external thermal insulation conditions of the power lithium battery module, the geometric angular position in the module is the most dangerous position, and the number of thermal trigger points is positively correlated with PN.