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Abstract In this article, an improved brake cooling simulation method is introduced. By this method, the vehicle parameters, such as weight, height of the center of gravity, wheelbase, and the like can be included to calculate the braking thermal load under different operating conditions. The effect of the brake kinetic energy regeneration (BKER) on the braking thermal load can also be calculated by this method. The calculated braking thermal load is then input to a coupled 3D simulation model to conduct flow and thermal simulation to calculate brake disc temperature. It is demonstrated that by this simulation method, the difference between the brake disc temperatures obtained from simulation and vehicle test can be controlled below 5%.

Abstract A unique torque converter test setup was used to measure the torque transmissibility frequency response function of four torque converter clutch dampers using a stepped, multi-sine-tone, excitation technique. The four torque converter clutch dampers were modeled using a lumped parameter technique, and the damper parameters of stiffness, damping, and friction were estimated using a manual, iterative parameter estimation process. The final damper parameters were selected such that the natural frequency and damping ratio of the simulated torque transmissibility frequency response functions were within 10% and 20% error, respectively, of the experimental modal parameters. This target was achieved for all but one of the tested dampers. The damper models include stiffness nonlinearities, and a speed-dependent friction torque due to centrifugal loading of the damper springs.

Abstract Composite ceramic brake discs are made of ceramic material reinforced with carbon fibers and offer exceptional advantages that translate directly into higher vehicle performance. In the case of an electric vehicle, it could increase the range of the vehicle, and in the case of conventional internal combustion engine vehicles, it means lower fuel consumption (and consequently lower CO2 emissions). These discs are typically characterized by complex internal geometries, further complicated by the presence of drilling holes on both friction surfaces. To estimate the aerothermal performance of these discs, and for the thermal management of the vehicle, a reliable model for predicting the air flowing across the disc channels is needed. In this study, a real carbon-ceramic brake disc with drilling holes was investigated in a dedicated test rig simulating the wheel corner flow conditions experimentally using the particle image velocimetry technique and numerically.

Abstract One of the key problems of battery electric vehicles is the risk of severe range reduction in winter conditions. Technologies such as heat pump systems can help to mitigate such effects, but finding adequate heat sources for the heat pump sometimes can be a problem, too. In cold ambient conditions below −10°C and for a cold-soaked vehicle this can become a limiting factor. Storing waste heat or excess cold when it is generated and releasing it to the vehicle thermal management system later can reduce peak thermal requirements to more manageable average levels. In related architectures it is not always necessary to replace existing electric heaters or conventional air-conditioning systems. Sometimes it is more efficient to keep them and support them, instead. Accordingly, we show, how latent heat storage can be used to increase the efficiency of existing, well-established heating and cooling technologies without replacing them.

Abstract Electrical connection plays an important role in not only direct heat transfer, but also the transmission of electric energy and the transformation of electrothermal effect in the parallel battery modules. The thermal propagation simulation research model was established based on the equivalent circuit and thermal runaway experimental research of a module formed by four parallel cells, which superimposes the discharge process and corresponding electrothermal effect in the process of thermal runaway and thermal propagation, and pays attention to the SoC (state of charge) state and corresponding thermal runaway energy release changes after cell discharged. Thermal runaway and propagation characteristics of parallel and non-parallel battery modules were analyzed and results showed that without considering the energy exchange between the system and the environment, the parallel battery module will accelerate the process of thermal propagation.

Abstract For spacecraft with high power consumption, it is reasonable to build the thermal control system based on a two-phase mechanically pumped loop. The heat-controlled accumulator is a key element of the two-phase mechanically pumped loop, which allows for the control of pressure in the loop and maintains the required level of coolant boiling temperature or cavitation margin at the pump inlet. There can be two critical modes of loop operation where the ability to control pressure will be lost. The first critical mode occurs when the accumulator fills with liquid at high heat loads. The second critical mode occurs when the accumulator is at low heat loads and partial loss of coolant, for example, due to the leak caused by micrometeorite breakdown. Both modes are caused by insufficient accumulator volume or working fluid charge.

Abstract The ASTM D130 was first issued in 1922 as a tentative standard for the detection of corrosive sulfur in gasoline. A clean copper strip was immersed in a sample of gasoline for three hours at 50°C with any corrosion or discoloration taken to indicate the presence of corrosive sulfur. Since that time, the method has undergone many revisions and has been applied to many petroleum products. Today, the ASTM D130 standard is the leading method used to determine the corrosiveness of various fuels, lubricants, and other hydrocarbon-based solutions to copper. The end-of-test strips are ranked using the ASTM Copper Strip Corrosion Standard Adjunct, a colored reproduction of copper strips characteristic of various degrees of sulfur-induced tarnish and corrosion, first introduced in 1954. This pragmatic approach to assessing potential corrosion concerns with copper hardware has served various industries well for a century.

Abstract Due to the incoming phase out of fossil fuels from the market in order to reduce the carbon footprint of the automotive sector, hydrogen-fueled engines are candidate mid-term solution. Thanks to its properties, hydrogen promotes flames that poorly suffer from the quenching effects toward the engine walls. Thus, emphasis must be posed on the heat-up of the oil layer that wets the cylinder liner in hydrogen-fueled engines. It is known that motor oils are complex mixtures of a number of mainly heavy hydrocarbons (HCs); however, their composition is not known a priori. Simulation tools that can support the early development steps of those engines must be provided with oil composition and properties at operation-like conditions. The authors propose a statistical inference-based optimization approach for identifying oil surrogate multicomponent mixtures. The algorithm is implemented in Python and relies on the Bayesian optimization technique.

Abstract The Wankel engine is an eccentric rotary internal combustion engine known for its simplicity, compactness, reliability, and efficiency. However, issues related to sealing, efficiency, and emissions have hindered its widespread use. Recent advancements in sealing technology, novel designs, material coatings, and alternative fuels have addressed some of these problems, leading to improvements in Wankel engine performance. This study examines these advancements in Wankel engine technology and proposes three potential applications for future automotive use. The first application involves utilizing a Wankel engine with a continuously variable transmission to replace the powertrain in conventional vehicles. The second application suggests replacing the engine in a series-parallel electric-hybrid architecture with a Wankel engine. Lastly, the third application explores using a Wankel engine as a range extender for electric vehicles.

Abstract Measuring the dynamic parameters of liquid fragments generated in the near-field of atomizing sprays poses a significant challenge due to the random nature of the fragments, the instability of the spray, and the limitations of current measuring technology. Precise determination of these parameters can aid in improving the control of the atomization process, which is necessary for providing suitable spray structures with appropriate flow rates and droplet size distributions for various applications such as those used in heat engines. In piston and gas turbine engines, controlling spray characteristics such as penetration, cone angle, particle size, and droplet size distribution is crucial to improve combustion efficiency and decrease exhaust emissions. This can be accomplished by adjusting the structural and/or operating parameters of the fuel supply system.

Abstract Lubrication has been a major area of interest in engineering. Especially in vehicle transmissions, lubrication plays a very crucial role because gears and bearings are constantly subjected to heavy loads. Proper lubrication is essential for maintaining system performance and ensuring endurance life. Insufficient lubrication can lead to excessive wear, increased friction, and eventually, failures in the transmission components. However, excess lubrication can result in power losses due to the resistance offered by the excessive lubricant. Therefore, achieving effective lubrication using optimized lubrication system design is vital for ensuring the longevity and efficiency of the transmission system. Majorly, two types of lubrication methods are used in transmissions: splash lubrication and forced lubrication. This article focuses on forced lubrication, where the lubrication system actively delivers the required flow of lubricant to specific locations within the transmission.

Abstract The current development of electric and hybrid electric vehicles has drawn more attention toward the development of electrical machines with high power densities. Though highly efficient, these machines heat up significantly during operation. By design, state-of-the-art water jacket cooling concepts remove the heat mainly through high internal thermal resistances of the electrical machine. The resulting maximum temperatures in the end winding region limit the achievable machine power output. In this study, alternative cooling concepts are presented, which efficiently use the existing heat conduction paths of an electric machine. For this purpose, two modeling methods for the stator windings were developed: a high-resolution approach that considers each individual wire and an abstract approach that uses zones of constant anisotropic thermal conductivity to specify the heat flow in the windings.

Abstract To improve the cornering performance, a torque vectoring differential (TVD) that generates a torque difference between the left and right wheels has been developed. Particularly, the use of multiple electric traction motors can easily achieve this. A TVD with a two-motor-torque difference amplification mechanism (TDA-TVD), which employs a unique alignment of planetary gears, has been studied and it can generate a larger torque difference compared to an individual-wheel-drive (IWD) system in the case of using the equal torque output from the traction motors. However, due to the mechanically complicated driving force transmission system including driveshafts and planetary gears, TDA-TVD is prone to cause torsional vibrations of the driveshaft, and the yaw rate of the vehicle body while differential torque is generated. A previous study derived a dynamic model TDA-TVD and designed a vibration suppression feedforward controller.

Abstract The reasonable engine cooling system design can give a better cooling of engine, the coolant flow direction and different cooling structure designs have great impact on the cooling performance and fuel consumption of engine. Therefore, to gain a deeper understanding of the impact of different cooling system designs on engine cooling performance, three different split cooling structures and two oil–water heat exchanger (OWHE) layouts are designed for a two-cylinder motorcycle engine. Three-dimensional CFD analysis method is used for analyzing the coolant velocity distributions and one-dimensional systematic analysis method is used for analyzing the system flow rate at those cooling structure designs and OWHE designs. Meanwhile, experimental investigation of different cooling structures and OWHE layouts on fuel consumption is conducted by the bench test of worldwide motorcycle test cycle.

Abstract In the field of thermal protection, detailed three-dimensional computational fluid dynamics (3D-CFD) simulations are widely used to analyze the thermal behavior on a full vehicle level. One target is to identify potential violations of component temperature limits at an early stage of the development process. In battery electric vehicles (BEVs), transient load cases play an increasing role in evaluating components and vehicle systems close to real-world vehicle operation. The state-of-the-art 3D simulation methodologies require significant time and computational effort when running transient load scenarios. One main reason is the conjugate characteristic of the problem, meaning that conduction within the component and convection into the surrounding air occur simultaneously. This requires a detailed consideration of both the fluid and structural domains.

Abstract Thermal runaway of lithium (Li)-ion batteries is a serious concern for engineers developing battery packs for electric vehicles, energy storage, and various other applications due to the serious consequences associated with such an event. Understanding the causes of the onset and subsequent propagation of the thermal runaway phenomenon is an area of active research. It is well known that the thermal runaway phenomenon is triggered when the heat generation rate by chemical reactions within a cell exceeds the heat dissipation rate. Thermal runaway is usually initiated in one or a group of cells due to thermal, mechanical, and electrical abuse such as elevated temperature, crushing, nail penetration, or overcharging. The rate of propagation of thermal runaway to other cells in the battery pack depends on the pack design and thermal management system.

Abstract In recent years we have seen a dramatic shift toward the use of lithium-ion batteries (LIB) in a variety of applications, including portable electronics, electric vehicles (EVs), and grid storage. Even though more and more car companies are making electric models, people still worry about how far the batteries will go and how long it will take to charge them. It is common knowledge that the high currents that are necessary to quicken the charging process also lower the energy efficiency of the battery and cause it to lose capacity and power more quickly. We need an understanding of atoms and systems to better comprehend fast charging (FC) and enhance its effectiveness. These difficulties are discussed in detail in this work, which examines the literature on physical phenomena limiting battery charging speeds as well as the degradation mechanisms that typically occur while charging at high currents. Special consideration is given to charging at low temperatures.

Abstract A typical modern automobile compressor-driven air conditioner, about powerful enough to cool a house, may not be needed even in very hot, humid climates if we combine insights from comfort theory with innovations in comfort delivery, photonics, and superefficient thermal and air-handling devices. Recent advances can successively minimize unwanted heat gain into the passenger cabin, cool people’s bodies rather than the vehicle, deliver highly effective radiant cooling, passively reject extracted heat to the sky, and, if needed, move air very efficiently and quietly to expand the human comfort range. Together these proven innovations may give automotive occupants excellent hot-weather comfort without refrigerative air conditioning.

Abstract Engine thermal management (ETM) is a promising technology that allows the reduction of harmful emissions and fuel consumption when the internal combustion engine (ICE) is started from a cold state. The key technology for ETM is the decoupling of the cooling pump from the crankshaft and the actuation of the pump independently. In this article, an electric engine cooling pump has been designed through a novel experimentally based procedure and operated on a vehicle equipped with an advanced turbocharged gasoline engine, particularly interesting for its hybridization potential. In the first phase, a dedicated experimental campaign was conducted off board on an engine identical to the one equipped in the vehicle to assess the characteristics of the cooling circuit and the reference pump performances.

Abstract Optimization is essential in real-life mechanical engineering problems that mostly are nonlinear, depend on mixed decision variables, and are usually subject to constraints. However, most of the studied problems are modelled assuming continuous variables. A limited number of studies have been devoted to cases with mixed variables. Moreover, there is a lack of algorithm treating mixed variable problems properly. This article introduces a hybrid algorithm that can handle constrained problems depending on continuous or mixed variables. The proposed algorithm combines two meta-heuristics, Jaya and particle swarm optimization (PSO). PSO is one of the most popular methods to solve nonlinear problems, and Jaya is a novel parameter-free optimization algorithm. This new hybrid optimization algorithm is proposed in order to improve the convergence speed and to investigate what improvements it will bring to optimization problem solutions.