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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 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 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 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 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 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 The heat pump system has the advantages of high heating efficiency and low energy consumption and is more and more widely used in vehicles. In order to improve the economy and thermal management effect, this article introduces the heat pump system into the fuel cell vehicle thermal management system, designs the fuel cell vehicle integrated thermal management system (VITMS), and conducts research. First, the temperature control objectives of each subsystem are determined, the refrigeration and heating schemes of the integrated thermal management system are designed, and the working state and pipeline design of system components under different working modes are clarified. Then the modeling is carried out according to the working mechanism of the key components in the thermal management system and the corresponding control strategy is proposed for the key components in the VITMS.

Abstract The input of combustion heat in engines has a major impact on the piston friction and the resulting wear of the piston skirt. The new methodology presented here enables the simulation of combustion heat input during motored operation, and thus a detailed investigation of the piston friction under realistic piston temperature profiles of real engine operation is possible. For this purpose a standardized engine test bench for motored friction evaluations was expanded to include, among other things, a movable high-power diode laser with special defocusing optics. The setup of the test engine is based on the FEV teardown step methodology [1] and has open access to the engine piston from above due to a cylinder head dummy. Thus, the heat input by means of a high-power diode laser into the piston crown can be made. The reduced engine structure also enables a precise and highly accurate evaluation of the piston friction.

Abstract High technology expertise and strong advancement in electric vehicles and Lithium (Li)-ion battery devices and systems have increased the speed of development and application of new equipment. It is reported that Li-ion battery life reduces almost by 60 days per degree temperature rise in an operational temperature of 30°C to 40°C, which makes cooling a high priority. The current study focuses on cooling the battery system using Phase Change Material (PCM) placed as bands of different dimensions around the prismatic battery. Eight novel designs of varying dimensions were constructed for three-volume scenarios. The heat generations considered in this study are 6,855 W/m3, 12,978 W/m3, 19,100 W/m3, and 63,970 W/m3. The data obtained was trained using an artificial neural network (ANN), and an equation was attained to fit the data. The optimum placement of PCM with respect to the number of bands and dimensions was achieved through a Genetic Algorithm.

Abstract Batteries have profound importance in today’s world as they are useful in powering the future without fossil fuels because of their properties, such as high energy density and durability. Volumetric and packing efficiency is better for a prismatic cell when compared with a cylindrical cell, whereas heat will be higher for a prismatic cell. This makes them a hot topic of research and development (R&D), with researchers finding ever more ways to improve. In this work, an attempt is made to study the effect of various mini-channel configurations on prismatic cell thermal management including the effect of C-rate, coolant flow rate, and coolant inlet temperature on temperature gradient and maximum cell temperature using ANSYS-Fluent by using an equivalent circuit model (ECM) in multi-scale multidimensional (MSMD) add-on module.

Abstract Results from a thermal survey measurement campaign on a four-cylinder Volvo engine was presented in Part I of this article. The focus was predominantly on heat transfer in the engine coolant jacket. This part presents numerical modeling focused specifically on the coolant flow and associated heat transfer in the coolant jacket using computational fluid dynamics (CFD), as a part of a high-resolution complete engine 3D conjugate heat transfer (CHT) model. With local nucleate boiling being an indispensable phenomenon in high power density engines, a dedicated boiling model is essential and is to be used in conjunction with CFD while analyzing heat transfer in the coolant jacket. This article validates a new boiling model with data obtained from the extensive thermal survey measurements, presented in Part I.

Abstract Nucleate boiling occurs inadvertently in the coolant jacket of high power density internal combustion engines, especially in vicinity of regions experiencing high thermal loads. Occurrence of boiling can be beneficial and be an efficient way to improve heat transfer locally near hot spots, but excessive boiling can be detrimental to structural integrity of the engine. While most of the efforts to understand boiling have been focused on experiments in simplified geometries, this article presents results from thermal survey measurement on a production engine. The purpose of the measurement campaign is to understand the intensity and extent of nucleate boiling occurring in different parts of the engine coolant jacket. This is achieved by sweeping across different input parameters, such as engine operating load point, cooling system operating pressure, coolant flow rate, and coolant inlet temperature.

Abstract Aiming at solving the battery electric vehicle (BEV) problems of high energy consumption and low efficiency in heating at low temperature, this study takes the thermal management system of BEV as the research object and develops an integrated thermal management control system based on heat pump air-conditioning for BEV. First, the functional requirements and optimal operating temperature range of each BEV subsystem are defined. Second, on the basis of the thermodynamic cycle principle of the air-conditioning system and compared with the traditional positive temperature coefficient thermistor (PTC) heating mode, the high heating efficiency and low energy consumption advantages of the heat pump system in winter are highlighted.

Abstract This article presents a novel aero-thermal coupled simulation approach for estimating the cooling performance of automotive vented disc brakes under the scenario of emergency braking. This approach couples the quasi-steady computational fluid dynamics (CFD) analysis in the fluid domain and the transient thermal calculation in the solid domain, and no finite element method (FEM)-based calculation is involved in the simulation. An advanced coupling strategy is proposed and used in the approach to solve the problem of boundary mismatch when data exchanging between the solid and fluid domains, and a specific point-in-polygon (P-in-P) algorithm is incorporated into the approach for a precise calculation of the braking heat flux through the brake disc.

Abstract Electrification has become less of a catchphrase and increasingly commonplace when discussing today’s locomotives. Engineers developing thermal management strategies (both component suppliers and system-level analysts) must be armed with effective tools to design and analyze essential components such as coolant pumps and study their behavior in an actual system. This study focuses on the analysis of twin screw pumps for cooling battery packs in hybrid and battery electric vehicles via three different approaches—experimental measurements, a one-dimensional (1D) thermodynamic chamber model, and a three-dimensional (3D) computational fluid dynamics (CFD) model. Experimental measurements are conducted to quantify the coolant’s volume flow rate and estimate hydraulic power consumption over a range of operating speeds and pump discharge pressures.

Abstract Electric Vehicle (EV) motors and batteries do not create heat in the same way as internal combustion engines; therefore, new specific thermal management solutions are required. Thus the development of adequate simulation methodologies to predict the thermal behavior of new devices and their influence on the thermal comfort of the users is a key point of investigation. In this work two different thermal comfort analysis methodologies are presented and compared with climatic chamber tests. The first one is a zero-dimensional (0D) approach, based on the calculation of the different heat fluxe, that predicts the evolution of average temperature in the vehicle cabin and calculates standard comfort index Predicted Mean Vote (PMV). The second one is a Computational Fluid Dynamics (CFD) method coupled with a simplified human comfort model, also called the manikin model; it calculates a detailed thermal analysis of the cabin and gives a comfort index for some body segments.

Abstract Technological advancements and growth in electric motors and battery packs enable vehicle propulsion electrifications, which minimize the need for fossil fuel consumption. The mobility shift to electric motors creates a demand for an efficient electric motor thermal management system that can accommodate heat dissipation needs with minimum power requirements and noise generation. This study proposes an intelligent hybrid cooling system that includes a gravity-aided passive cooling solution coupled with a smart supplementary liquid cooling system. The active cooling system contains a radiator, heat sink, variable frequency drive, alternating current (AC) fan, direct current (DC) pump, and real-time controller. A complete nonlinear mathematical model is developed using a lumped parameter approach to estimate the optimum fan and pump operations at each control interval.