Analysis Of Thermal Behavior Research Articles

Simulation of thermal behavior evolution in lithium-ion pouch cells using a coupled reaction-thermal-expansion model

Conventional lithium-ion battery thermal simulation methods establish a coupled heat generation/transfer model to calculate the temperature evolution for hard-pack cells. However, the thermal behavior evolution of a pouch cell includes multi-processes such as heat generation, gas production, heat transfer, and pouch expansion. There is currently a lack of computational models for predicting the multi-state parameter evolution in temperature and pressure. In this paper, an efficient and accurate thermal behavior simulation algorithm for lithium-ion pouch cells is developed. A heated/exothermic two-stage hypothesis for the thermal behavior evolution in pouch cells was established under thermal abuse conditions. Analytical models of exothermic reaction, heat transfer and pouch expansion were formulated and integrated into a unified thermal behavior analysis framework. The proposed algorithm simulated the thermal behavior evolution in four commercial lithium-ion pouch cells. The computational and experimental results showed the calculation errors of the cell temperature and gas volume for the four samples were less than 3% and 5%, respectively. In terms of efficiency, the calculation time of the algorithm is within milliseconds. The accuracy and efficiency of the proposed algorithm are verified.

Analysis of Volatile Compounds, Composition, and Thermal Behavior of Coffee Beans According to Variety and Roasting Intensity.

This study aimed to investigate the ways in which the thermal behavior, composition, and volatile compound contents of roasted coffee beans depend on variety and roasting intensity. The thermal analysis revealed various transformations in coffee composition, namely, drying, water loss, and decomposition of polysaccharides, lipids, amino acids, and proteins. The results showed that volatile compounds are released differently in coffee depending on coffee type and degree of roasting. The most abundant volatile compounds present in the samples were 2-butanone, furan, 2-methylfuran, methyl formate, 2.3-pentanedione, methylpyrazine, acetic acid, furfural, 5-methyl furfural, and 2-furanmethanol. The total polyphenol contents ranged between 13.3 and 18.9 g gallic acid/kg, being slightly higher in Robusta than in Arabica varieties and in more intensely roasted beans compared to medium-roasted beans. The Robusta variety has higher mineral contents than Arabica, and the contents of most minerals (K, Ca, Mg, Fe, Cu, P, N, and S) increased with roasting intensity. Discrimination between coffee varieties and roasting intensities is possible based on mineral and polyphenol contents.

Temperature behaviors of an arch bridge through integration of field monitoring and unified numerical simulation

Varying temperature may cause a non-uniform temperature distribution of a bridge and lead to excessive movement and stresses of the structure. Traditional thermal analyses of bridges adopt a divide-and-conquer approach, which conducts a simplified 2D or local 3D heat-transfer analysis and then a global 3D structural analysis by inputting the calculated temperature into another bridge model. This process requires considerable manual intervention and is inefficient and may lead to inaccurate results. This study develops a unified approach of heat-transfer and structural analyses for the first time to calculate the temperature distribution and the associated responses of an entire structure by integrating the field monitoring data. The arch footbridge at the Hong Kong Polytechnic University is used as a testbed, and a detailed finite element model (FEM) of the bridge is established. The measured air temperature and solar radiation are used as the thermal boundary conditions. The hemisphere technique is adopted to calculate the view factor between different surfaces of the bridge, which are then used to obtain the solar radiation on all external surfaces in different instants on different dates. The 3D global hear-transfer analysis is conducted to obtain the temperature distribution of the entire bridge. The calculated temperature data of the bridge are then automatically input into the same FEM of the bridge to calculate the temperature-induced bridge responses via the structural analysis. The heat-transfer analysis and structural analysis share the same FEM while using different element types. Therefore, the manual intervention is avoided. The calculated and monitored temperature data and responses show a good agreement. The developed new unified approach enables an automatic and efficient analysis of thermal behaviors of bridges. This approach can be extended to other types of bridges.

Thermal behavior and kinetics analysis of co-combustion of petroleum coke and paper sludge-derived hydrochar

The co-combustion reactivity and kinetics of petroleum coke (PC) and paper sludge-derived hydrochar (PS) were investigated via thermogravimetric analysis. The physical and chemical structure features were also systematically tested. The results show that the combustion process of PS could be divided into three stages, while for PC only one stage could be clarified. Due to high volatile content, developed pore structure and low carbon-order degree, the combustion reactivity of PS was higher than that of PC. Although the ignition property of the blends could be significantly improved by addition of PS, it changed little for the burnout temperature and as a result the combustion intensity was deteriorated. For the samples with addition of PS from 20 % to 80 %, the comprehensive combustion index decreased from 3.69 × 10-15 to 2.12 × 10-15. The Kissinger AkahiraSunose model-free method was used in the co-combustion reaction of PC and PS, and good fitting results were obtained. For different samples with varying addition of PS, the activation energies were in the range of 107.51–198.44 kJ/mol, with the lowest value obtained at 20 % of PS, which was also the optimum proportion for co-combustion of PC and PS.

A simplified modelling approach for thermal behaviour analysis in hybrid plasma arc-laser additive manufacturing

Hybrid plasma transferred arc (PTA)-laser additive manufacturing (AM) has the potential to build large-scale metal components with high deposition rate and near-net shape. However, the process is complex with many parameters adjustable for process control, which determine the thermal behaviour and thus the final structure and properties of the deposited components. In this study, a three-dimensional steady-state finite element model with two independent circular surface heat sources was developed, validated, and used to analyse the thermal behaviour in hybrid PTA-laser AM of Ti-6Al-4V. Artificial conductivity in three orthogonal directions was applied in the melt pool to compensate for the melt pool convection effect. The predicted melt pool geometry, heat-affected zone and thermal cycles had good agreement with the corresponding experimental data. This model has advantages over the widely used volumetric heat source model, since it is more representative of the energy sources used, giving accurate thermal prediction for a wide range of process parameters. As the heat source parameters in this model are directly linked to the actual arc/laser size, it enables to capture heat source size effect on the hybrid process. In addition, it is easier to calibrate compared to the model with volumetric heat sources due to the fewer empirical parameters involved. It was found that in the investigated ranges of all the parameters, the melt pool geometry is more sensitive to laser power and travel speed compared to arc-laser separation distance and laser beam size. The full-field distributions of the cooling rate and temperature gradient in the hybrid process were obtained and the roles that different process parameters played on them were also studied, which provided useful thermal information for metallurgical analysis.

Computational study of the effect of different doping elements on the thermal conduction properties of graphene nanoribbons

The dopant's atoms of various elements can be incorporated into the crystal lattice of graphene for the purpose of modulating its structural, optical and electrical properties. While the dopant's presence negatively affects the thermal conductivity, the exact effect of doping is still poorly understood and the mechanisms involved remain obscure. The effect of different doping elements on the thermal conductivity of graphene ribbons was investigated by performing molecular dynamics simulations to understand how impurities affect the thermal conduction properties of the nanostructured material. Graphene ribbons were doped with silicon, boron, or nitrogen elements to modify their nanostructure and thermal properties. The importance of edge structure was evaluated in comparison with that of doping. The Callaway model and the Einstein's model were used to provide the theoretical upper and lower bounds on the thermal conductivity. The contribution of optical phonons at different temperatures was evaluated in order to further understand the microscopic mechanisms of thermal conduction in the two-dimensional doped crystal. A computational analysis of thermal behavior was carried out in terms of the maximum density of states. The results indicated that a small number of dopant atoms can greatly change the ability to conduct heat. The thermal conductivity of the doped nanomaterial decreases successively in the order of nitrogen, boron, and silicon. Acoustical phonons still dominate the thermal conduction in the doped crystal, but the contribution of optical phonons become larger, especially at higher temperatures. The contribution of phonons in the optical branches increases with the doping concentration and can be as large as 6.0 %. In the presence of doping, the edge structure does not significantly affect the thermal conductivity and the maximum density of states. When graphene is heavily doped, the effect of ribbon length is insignificant while doping becomes dominant. The results have significant implications for the understanding of the relations between doping elements and thermal conduction properties.

Effects of oxidative torrefaction conditions on the biomass liquid chemical looping reaction from the perspective of thermal behavior and kinetic analysis

Biomass liquid chemical looping conversion process (BLCLP) can produce a high-temperature oxygen-depleted stream. Utilizing the oxygen-depleted air as a torrefaction medium can enhance biomass reactivity and achieve higher energy efficiency. This study aimed to investigate the effect of torrefaction conditions on biomass reactivity in the BLCLP. The torrefaction under proper working conditions effectively enhanced the release of biomass volatiles. The increase in the activation energy of biomass pyrolysis after oxidative torrefaction indicated the need for proper control of the torrefaction condition. More importantly, oxidative torrefaction promoted the reactivity between biochar and liquid oxygen carrier, which was crucial for the BLCLP. The activation energy of the reaction between biochar and Sb2O3 liquid oxygen carrier calculated by the DAEM method was 289.75–296.79 kJ·mol−1, guiding the subsequent reactor design. Ultimately, the optimal torrefaction conditions for the BLCLP were determined as 270 °C and 3 vol% oxygen content.

Physicochemical properties and pyrolysis behavior of petcoke with artificial neural network modeling

Petcoke is a byproduct of heavy crude oil refining at an enormous scale, and insights into the physicochemical properties, thermal degradation behavior, decomposition kinetics, and thermodynamic analysis of petcoke pyrolysis are crucial for the efficient design of pyrolysis reactor systems. In this study, proximate and ultimate analyses were performed, and petcoke was found to have a high fuel ratio with high carbon, high sulfur, and considerably low ash content, implying that it is a less reactive fuel. Advanced analytical techniques such as SEM, BET, FTIR, and petrography indicated that petcoke has a considerably low pore volume and predominantly inorganic graphitic carbon. Furthermore, thermogravimetric analysis was examined at four different heating rates of 10, 20, 30, and 40 K/min and petcoke exhibited a low pyrolysis performance, which was confirmed by the devolatilization index and pyrolytic parameters. The activation energies and frequency factors estimated by three model-free methods (DAEM, FWO, Friedman) were in the range of 221.6–235.9 kJ/mol and 1011–1012 s−1, respectively. In addition, thermodynamic analyses were examined and the thermal degradation behavior of petcoke pyrolysis was modeled using an artificial neural network; the NN-2-12-12-2 model with Tansig-Tansig transfer functions was found to be the best fit. This study enabled the identification of the fundamental characteristics of petcoke fuel, and these results provide useful information regarding the design, utilization, optimization, and limitations of petcoke pyrolysis systems.

Thermo-Mechanical Behavior of Aluminum Matrix Nano-Composite Automobile Disc Brake Rotor Using Finite Element Method.

Analysis of mechanical and thermal behaviors during braking has become an increasingly important issue in many transport sectors for different modes of transportation. Brake failure generated during braking is a complex phenomenon confronting automobile manufacturers and designers. During braking, kinetic energy is transferred to thermal energy, resulting in the intense heating of disc brake rotors that increases proportionally with vehicle speed, mass, and braking frequency. It is essential to look into and improve strategies to make versatile, thermally resistant, lightweight, high-performance discs. As a result, this study uses the finite element method to conduct a thermo-mechanical analysis of aluminum alloy and aluminum matrix nano-composite disc brake rotors to address the abovementioned issues. The FEA method is used for the thermo-mechanical analysis of AMNCs for vented disc brake rotor during emergency braking at 70 km/h. From the results obtained, aluminum base metal matrix nano-composites have an excellent strength-to-weight ratio when used as disc brake rotor materials, significantly improving the discs’ thermal and mechanical performance. From the result of transient thermal analysis, the maximum value of heat flux obtained for aluminum alloy disc is about 8 W/mm2, whereas for AMNCs, the value is increased to 16.28 W/mm2. The result from static analysis shows that the maximum deformation observed is 0.19 mm for aluminum alloy disc and 0.05 mm for AMNCs disc. In addition, the maximum von Mises stress value of AMNC disc is about 184 MPa. The maximum von Mises stress value of aluminum alloy disc is about 180 MPa. Therefore, according to the results, the proposed aluminum base metal matrix nano-composites are valid for replacing existing materials for disc brake rotor applications.

Thermal Environment and Behavior Analysis of Confined Cows in a Compost Barn.

Simple SummaryThe use of the compost barn system has increased in dairy farms as it provides greater well-being to animals, favoring productivity. Thus, studies related to the thermal environment and behavior are paramount to assessing animal welfare and optimizing management. The objective of this work was to characterize the thermal environment inside a compost barn and to evaluate the standing and lying behavior of cows through images covering the four seasons. Dry bulb temperature, dew point temperature, and relative humidity data were collected every 10 minutes during the analyzed days, calculating the temperature and humidity index (THI). Filming was performed inside the barn, which was analyzed visually and in an automated way to assess the behavior of these animals. For the automated analysis, an algorithm was developed using Artificial Intelligence tools, YOLOv3. It was observed that in the experimental period the highest mean values of THI were observed during the afternoon and autumn. The animals’ preference to lie down on the bed for most of the day was verified. Regarding the developed algorithm, it was observed that it could detect cow behavior (lying down or standing), concluding that artificial intelligence was successfully applied and can be recommended for such use.The compost barn system has become popular in recent years for providing greater animal well-being and quality of life, favoring productivity and longevity. With the increase in the use of compost barn in dairy farms, studies related to the thermal environment and behavior are of paramount importance to assess the well-being of animals and improve management, if necessary. This work aimed to characterize the thermal environment inside a compost barn during the four seasons of a year and to evaluate the standing and lying behavior of the cows through images. The experiment was carried out during March (summer), June (autumn), August (winter), and November (spring). Dry bulb temperature (tdb, °C), dew point temperature (tdp, °C), and relative humidity (RH,%) data were collected every 10 minutes during all analyzed days, and the temperature and humidity index (THI) was subsequently calculated. In order to analyze the behavior of the cows, filming of the barn interior was carried out during the evaluated days. Subsequently, these films were analyzed visually, and in an automated way to evaluate the behavior of these animals. For the automated analysis, an algorithm was developed using artificial intelligence tools, YOLOv3, so that the evaluation process could be automated and fast. It was observed that during the experimental period, the highest mean values of THI were observed during the afternoon and the autumn. The animals’ preference to lie down on the bed for most of the day was verified. It was observed that the algorithm was able to detect cow behavior (lying down or standing). It can be concluded that the behavior of the cows was defined, and the artificial intelligence was successfully applied and can be recommended for such use.

Thermal behavior analysis of wood-based furniture applied with phase change materials and finishing treatment for stable thermal energy storage

In recent times, indoor environments have become increasingly important for occupants who spend most of their time indoors. The use of furniture, which occupies a large specific surface area in interior spaces, is expanding. Medium-density fiberboard, particleboard, and plywood are generally used as wood-based furniture materials, and these materials require surface-finishing treatment to maintain quality and efficiency. Among various types of finishing treatments, low-pressure melamine (LPM) coating can be applied to other materials using the hot pressure process. The coating provides an exterior pattern, reduces the emission of pollutants, and resists moisture. However, when a furniture item is fixed in environment with a large temperature difference, water vapor condensation is likely to occur. In particular, the materials of a built-in furniture item require to be improved. As the use of indoor furniture increases, various functions are required. In this study, phase change materials (PCMs) were applied to wood-based furniture materials to reduce their sensitivity to temperature changes and provide effective heat storage properties. This application process was performed using three types of materials, and the results indicated high enthalpy and thermal storage performance. The PCM/wood material of the surface of the specimen required 187 min to reach the peak temperature at a high ambient temperature and exhibited reduced temperature sensitivity. Moreover, LPM-based finishing treatment is an effective method to prevent PCM leakage.

Phytic Acid-Iron/Laponite Coatings for Enhanced Flame Retardancy, Antidripping and Mechanical Properties of Flexible Polyurethane Foam.

The use of flexible polyurethane foam (FPUF) is severely limited due to its flammability and dripping, which can easily cause major fire hazards. Therefore, choosing an appropriate flame retardant to solve this problem is an urgent need. A coating was prepared on the FPUF surface by dipping with phytic acid (PA), Fe2(SO4)3·xH2O, and laponite (LAP). The influence of PA-Fe/LAP coating on FPUF flame-retardant performance was explored by thermal stability, flame retardancy, combustion behavior, and smoke density analysis. FPUF/PA-Fe/LAP has a good performance in the small fire test, which can pass the UL-94 V-0 rating and the limiting oxygen index reaches 24.5%. Meanwhile, the peak heat release rate values and maximum smoke density of FPUF/PA-Fe/LAP are reduced by 38.7% and 38.5% compared with those of neat FPUF. After applying PA-Fe/LAP coating, the value of fire growth rate index decreases from 10.5 kW/(m2·s) to 5.1 kW/(m2·s), dramatically reducing the fire risk. Encouragingly, the effect of PA-Fe/LAP coating on cyclic compression and permanent deformation is small, which is close to that of neat FPUF. This work provides an effective strategy for making a flame-retardant FPUF with antidripping and keeping mechanical properties.

Multiscale numerical and experimental analysis of cooling-induced thermal shrinkage behaviors and residual stresses in 2.5D woven fiber/aluminum matrix composites

The cooling-induced thermal shrinkage behavior and residual stress in fabrication of 2.5D woven fiber reinforced Al composites were investigated by numerical and experimental approach. A microscale finite element (FE) model was established to determine the transversely isotropic thermal shrinkage of the Al-impregnated yarns. The validated properties were subsequently input into a mesoscale FE model for the composites, in which the temperature-dependent properties of the constituent materials were incorporated. Parallel experiments were carried out to verify the thermal shrinkage behaviors and the residual stresses that were predicted by the FE simulations. The residual stress distribution of the matrix pocket, warp and weft yarns were studied, and their contributions to the local damage of matrix pocket and interface were analyzed. Based on the verified model, the effect of fabric structure on the residual stresses and macroscopic shrinkage properties were parametrically evaluated. The results make a contribution to evaluating the cooling-induced residual stress, local damage, and shrinkage behavior of metal matrix composites reinforced with complex fabric.

Experimental Analysis of Thermal Behavior of a Lithium-Ion Battery using Constant Voltage under Different Cooling Conditions

Experimental Analysis of Thermal Behavior of a Lithium-Ion Battery using Constant Voltage under Different Cooling Conditions

Thermal behavior analysis of lithium-ion capacitors at transient high discharge rates

As one of the prospective high-rate energy storage devices, lithium-ion capacitors (LICs) typically incorporate non-Faradaic cathodes with Faradaic pre-lithiated anodes. LICs that deliver power density at high-rate discharging process can be accompanied by overheating problems which result in capacity deterioration and lifetime reduction. Therefore, it is essential to conduct a comprehensive analysis of the heat generation of LICs. The thermal behavior of pouch lithium-ion capacitors in this work is systematically investigated at transient high-rates from 1C to 550C. The heat transfer mechanisms of each part in the overall thermal behavior are quantified in detail during discharging processes. As the discharge rate increases, the temperature curve shows an upward parabolic trend at the end of discharge, with a maximum temperature of 33.68 °C at 200C.The proportion of irreversible heat to total heat generation is close to 80 % at 550C, but the temperature at the end of discharge decreases owing to the reduced discharge time. The actually measured temperature rise is compared with the one calculated using the intermittent current method, the voltage-current (VI) characteristic method and the alternating current impedance method. It can be found that the intermittent current method calculated temperature trends are in good agreement with the measured values better than other methods, because the polarization internal resistance is significantly related to the discharge time interval. These results would provide the basis for further development of a thermal model of the cell, in order to rationally design the cooling system to avoid overheating and degradation of the cells.

Evaluation of thermal behavior and life cycle cost analysis of greenhouses with bio-phase change materials in multiple locations

Global warming and energy crisis have forced the communities to pursue sustainable development. Agriculture and food production are one of the fields that needs high amount of energy and produce large amount of emissions each year. In order to create sustainable development in these fields, this paper attempts to add organic fatty acid ester phase change materials to the greenhouses, which are one of the major sources of food production, for the first time. Designbuilder software and Energyplus calculating engine are employed to optimize greenhouses by adding various types of phase change materials to them. As the plan of this research is applicable to any locations, eight different locations which have dry climates are selected for the study. This paper also creates a plan that can be used by developers and researchers to select the appropriate phase change materials for greenhouses according to the climate, location and season. All energy, environmental and economic aspects of the projects are analyzed closely. The results of energy analysis indicated that phase change materials can save up to 14,577 kWh electricity in greenhouses per year. The amount of saved energy is different for each type of phase change materials. Results also showed that bioPCM-Q27 can reduce considerable amount of electricity consumption compared with the other ones. In addition to electricity, adding phase change materials to greenhouses will result a significant drop in their gas consumption during cold seasons. Up to 1348 kWh natural gas energy can be reduced each year by adding phase change materials to the greenhouses. The paper also analyzed the environmental effects of the projects. The largest amount of carbon reduction is equal to 6.2 tons per year and can be even increased to 8.6 tons per year. Financial analysis of the research also made it clear that adding phase change materials to greenhouses can save up 59 % of future costs of the project.

Thermal behavior and kinetic analysis of torrefied coconut fiber pyrolysis

The present work discusses the effect of mild torrefaction on coconut fiber pyrolysis kinetics. Firstly, it was evaluated by statistical experimental design (473–523 K, 15–45 min) in the fixed bed reactor. The results showed a reduction of volatile matter content and atomic ratios of hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C), and an increase in heating values. Secondly, the thermal decomposition was quantified by thermogravimetric analysis, in which the hemicellulose fraction was partially removed after torrefaction. Thirdly, the activation energy was determined by two isoconversional methods (single-step reaction) obtaining a variation from 184 to 238 kJ/mol. Fourthly, the kinetics of thermal decomposition of the torrefied sample was well-described (average deviation <3%) by three independent parallel reactions scheme assuming first-order reactions with activation energies of 99.5, 203.2 and 45.4 kJ/mol for hemicellulose, cellulose, and lignin, respectively. Finally, these kinetic parameters remained constant at different heating rates, providing more reliable information, which can be used to model the pyrolysis of coconut fiber in future works.

Effects of thermal conductive fillers on energy storage performance of Form-Stable phase change material integrated in Cement-Based composites

• Graphite and nTiO 2 were used to enhance thermal performance of PCM cement composite. • TGA results showed that the PCM composites were thermally stable. • Graphite and nTiO 2 improved the heat transfer rate of PCM composite by 50%. • SEM showed the Graphite and nTiO 2 particles uniformly dispersed in the PCM. • Thermally enhanced PCM composite reduced the peak indoor temperature by 2.5 °C. Energy consumption to achieve thermal comfort in buildings is one of the significant challenges in the construction industry. Hence, applying thermal energy storage (TES) systems, such as phase change material (PCM), is increasingly being considered as a promising solution. However, the low thermal conductivity of PCM has a negative effect on the thermal cycle and, consequently, the efficiency of the TES system. This study aims to develop a novel form-stable PCM cement composite and investigates the effects of two thermal conductive fillers (TCFs), graphite powder and nano titanium dioxide (nTiO 2 ), on the thermal performance of PCM cement composites. For this purpose, the TCFs at different mass fractions (1 and 3 wt%) were dispersed in the PCM using sonication and impregnated into expanded glass aggregates (EGA). The microstructure studies revealed that TCF was well dispersed in the PCM and PCM-TCF was successfully impregnated into the EGA. The results of thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FT-IR) demonstrated that there was no chemical reaction between PCM and TCFs, and the PCM-TCF were thermally stable in the operating temperature ranges. The differential scanning calorimetry (DSC) analysis showed that the latent heat capacity of PCM-TCF remained reasonable with a maximum deduction of 9.6% and supercooling temperature enhancement up to 3.4 °C. The thermal behaviour analysis obtained from infrared thermography (IRT) imaging showed a 50% improvement in the heat transfer rate of the PCM composite. Moreover, a room model experiment revealed that integrating TCFs into PCM significantly enhanced the performance of EGA/PCM cement mortar. This is evidenced by a reduction in peak indoor temperature of up to 2.5 °C compared to the control sample.

Dependence of the lubrication enhancement of alkyl-functionalized graphene oxide and boric acid nanoparticles on the anti-oxidation property

The influence of anti-oxidation property of nanoparticles on the tribological properties is rarely reported. In this study, the alkyl-functionalized graphene oxide (FGO) and alkyl-functionalized boric acid (FBA) were fabricated as oil additives to explore their lubrication effectiveness. FBA exhibited remarkable lubricating properties which reduced friction coefficient by approximately 24 % and the wear depth by about 94 %. However, the friction coefficient and wear depth of FGO were reduced by only 9.5 % and 44 %, respectively. Worn surface analysis shows a bunch of deep-plowing on rubbing surface in the case of FGO, while the wear scar was smooth and almost wear-free for FBA. Lubrication mechanism analysis by X-ray Photoelectron Spectroscopy revealed the formation of carbon-based tribofilm for FGO and boron-based tribofilm for FBA during rubbing. In the thermal behavior analysis, graphene oxide (GO) nanoparticles were completely decomposed at 650 °C, whereas, B2O3 nanoparticles remained stable. It indicated that the excellent thermal stability and anti-oxidation property of boron-based tribofilm benefited to the lubrication enhancement. This study highlights the importance of oxidation resistance in designing novel nanoparticle additives, and the enhancement of oxidation resistance of GO will be a promising way to further application as oil additives.

Modeling and Analysis of Thermal Behaviour for Brake Discs

Abstract Focusing strictly to the braking assembly system, it is an important key factor for safety, does not matter if it can be found on cars, motorcycles, planes or bicycles. The principal aspect is to transform the energies that act on the system, which are kinetic and potential, then leads to a speed decrease of the vehicle until it stops. The purpose of this paper is to analyze five possible variants of the geometry of the brake disc, each geometry being different from the other. Because for a more efficient release of heat, the five chosen geometries of the discs have on their surface vanes, holes, in order to remove heat from their surface. For the actual making of the discs, the chosen models were made and designed in the CATIA V5 design program. The next step in this work was to perform analyzes and simulations for the selected disks. At the same time, the material chosen for them was considered. The 3D models were imported into the ANSYS analysis program, where individual analyzes were performed for each brake disc, and a comparison was made between the values of each one.