Thermal management of battery packs is essential to keep the cell temperatures within safe operating limits at all times and, hence, ensure the healthy functioning of an EV. The life cycle of a cell is largely influenced by its operating temperature, maintaining the cell temperature in its optimum range improves its longevity by decreasing its capacity fade rate and in turn extending the life of an EV. Liquid cooling techniques have proven to be cost-effective compared to other techniques such as air cooling, PCM-based in terms of performance in the given volumetric constraints. The battery thermal management solution being presented employs a tabbed type liquid cooling technology that achieves low-temperature differentials for an in-house designed battery pack consisting of 320 LFP cells (Size: 32700) with a total voltage and capacity of 27V and 240Ah respectively. Thermal design of the battery pack considers maximum dissipation when continuously operating at 1C-rate conditions.
Motor thermal management of electric vehicles (EVs) is becoming more significant due to its close relations to vehicle aerodynamic performance and energy consumption, while computer aided engineering (CAE) plays an important role in its development. A 1D-3D coupled model is established to characterize transient thermal performance of the motor in an electric vehicle on a high performance computer (HPC) platform. The 1D motor thermal management model is integrated with the 1D powertrain model, and a 3D thermal model is established for the motor, while online data exchange is realized between the 1D and 3D models. The 1D model gives boundaries such as inlet coolant temperature, mass flowrate and motor heat generation to the 3D model, while 3D gives back boundaries such as heat transfer to coolant simultaneously. Transient simulations are performed for the 140kph(20℃) driving cycle, and the model is calibrated with experimental data.
The COVID-19 pandemic affected mobility in many ways- from changing business models of moving passenger to delivering packages and food, developing cleaning protocols for interiors and increasing the awareness of consumers to the hidden dangers of pathogens and viruses in an enclosed space. A trend towards healthy cars is believed to remain after the current pandemic and has led to the emergence of new safety features, from CO2 gas sensors, to antimicrobial fabrics, and enhanced air purifiers. While air purifiers trap contaminants using cartridge filters, they are not particularly efficient at removing viral particles and create large pressure drops, which must be compensated with larger fans, increasing noise and power consumption, both of which are not optimal for vehicle HVAC systems. However, air purifiers act as a pressure head, which limits their utility. UVC was not previously an option because mercury lamps pose their own electrical and chemical hazards.
The emergence of additive manufacturing (AM) technology has enabled the internal cooling channel layout for high pressure aluminium die casting (HPADC) tools to be designed and modified without topological constraint. Optimisation studies of a full industrial HPADC mould for extending the tool service life has received limited attention due to the high geometrical complexity and the various physics with multi time and length scales in addition to the manufacturability limitations. In this work a new computational efficient algorithm that employs the adjoint optimization method has been developed to optimize the coolant channels layout in a complete mould with various 3D printed inserts. The algorithms reduced significantly the computational time and resources by decoupling the fluid flow in the coolant channels from the tool and simulating them separately.
In this paper, a linear oscillatory actuator with moving magnets used in active engine mount is modeled and theoretically analyzed considering its performance decline at high temperature. Firstly, a finite element model of the linear oscillatory actuator with moving magnets is established. The actuator force is decomposed to ampere force and cogging force through formation mechanism analysis. By using the finite element model, ampere force and cogging force of the linear oscillatory actuator with moving magnets under different current loads and different mover positions are calculated. The finite element model and calculation method are validated by bench level test. The voice coil constant and cogging coefficient at room temperature are identified, which indicates the actuator force is a linear model related to the current and the mover position.
This study investigated the plastic deformation behavior of 304 stainless steel thin-walled tubes under axial compression by means of numerical calculation and theoretical analysis. It was found that the plastic deformation length of thin-walled tube determined the formability of folds and the work done in the whole axial compression process. To reveal the relation between the range of plastic deformation length and tube geometry parameters, regression equations were established using the quadratic regression orthogonal design method. Experiments were conducted to validate the equations. The process windows for forming a single fold and tube joining at ends had been printed ultimately. The results showed that the regression equations can accurately predict the range of plastic deformation length for forming a single fold.
The main Objective of this paper is to remove the abnormal noise by altering the modal frequency. From the numerical method, very high deflection is reported at HVAC assembly level, cause unwanted vibrations. Due to high deflection at low frequency (1st modal frequency), abnormal noise coming near blower assembly under experimentally dynamic conditions. Then, improved the design by adding the stiffeners on the flange to minimize unwanted vibrations and hence abnormal nose. Thereafter, modal frequency has been increased and reduced the high deflection. The same has been validated experimentally with proto sample and found no abnormal noise from the blower side. A good correlation between the numerical and experimental result is observed and matching numerical & experimental modal frequencies within the accuracy of ±10%.
As one of the key components of the heat pump system, the electronic expansion valve mainly plays the role of throttling and reducing pressure in the heat pump system. The refrigerant flowing through the orifice will produce complex phase change. It is of great significance to study the internal flow field by means of CFD calculations. Firstly, a three-dimensional fluid model is established and the mesh is divided. Secondly, the phase change model is selected, the material is defined and the boundary conditions are determined. According to the principle of the fluid passing through thin-walled small holes, the flow characteristics of electronic expansion valve are theoretically analyzed. Then the flow characteristics of expansion valve are numerically calculated, and a bench for testing mass flow rate of the expansion valve is built. Then the theoretical value, CFD value and experimental value are compared to verify the correctness of the established three-dimensional fluid model.
Hydrogen Internal Combustion Engines (H2-ICEs) are being investigated due to their minimal criteria pollutant and zero CO2 tailpipe emissions. However, oil filters and non-hot joint gaskets have rubber material that can be damaged and deteriorate due to direct or indirect exposure to the high temperature and high-pressure hydrogen in a H2-ICE. Thus, the effects on the properties of a rubber exposed to a hydrogen environment need to be reviewed. In this review paper, the transportation, chemical and mechanical properties of a rubber exposed directly or indirectly to high temperature and high-pressure hydrogen in a H2-ICE have been reviewed. The compatibility of rubber materials used in H2-ICE has been explored. The effects of high-pressure hydrogen on the transportation, chemical and mechanical properties of NBR and HNBR have been reviewed.
Decreasing fuel consumption in Internal Combustion Engines (ICE) is a key target for engine developers in order to achieve the CO2 emissions limits during a standard cycle. In this context, reduction of engine friction can help meet those targets. The use of Low Viscosity Engine Oils (LVEOs), which is currently one of the avenues to achieve such reductions, is studied in this manuscript through a validated numerical simulation model that predicts the friction of the engine’s piston-cylinder unit, journal bearings and camshaft. These frictional power losses are obtained for four different lubricant formulations which differ in their viscosity grades and design. Results show a maximum friction savings of up to 6% depending on the engine operating condition, where the major reductions come from hydrodynamic-dominated components such as journal bearings, despite an increase in friction in boundary-dominated components such as the piston-ring assembly.
Passive pre-chamber ignition concept has been proven as an excellent solution to increase the combustion velocity and to allow the use of different strategies that are able to reduce pollutant emissions of internal combustion engines. Although pre-chamber combustion concept has been extensively studied, the evaluation of the heat release rate (HRR) inside the pre-chamber and its effects on the performance of the engine has not been widely investigated. In this work, newly designed passive pre-chambers with different nozzle-hole patterns, featuring combinations of radial and axial holes, were experimentally investigated in a 4-stroke single-cylinder light-duty optical engine. All the pre-chambers analyzed had a narrow throat geometry to increase the velocity of the ejected jets. An inductive and a nanosecond spark ignition systems were implemented.
Increasing demands regarding the efficiency and emissions of internal combustion engines will require higher peak firing pressures and increased indicated mean effective pressures in the future. Adaptation of these parameters will result in higher thermal and mechanical loads that act on core engine components. To meet the future requirements, it is essential to make changes to the design of the tribological system, which is composed of the piston, piston rings, liner and lube oil, while maintaining the robustness and reliability of the engine and its components. Modification of the tribological system requires in-depth knowledge of wear and friction. This paper presents the setup of a model of the tribological system (piston, piston rings, liner and lube oil) of a large gas engine in the commercial software AVL EXCITE™ Piston&Rings as well as its calibration and validation with data obtained from a test bed.
Machine learning algorithms are effective tools to reduce the number of engine dynamometer tests during internal combustion engine development and/or optimization. This paper provides a case study of using such a statistical algorithm to characterize the heat transfer from the combustion chamber to the environment during combustion and during the entire engine cycle. The data for building the machine learning model came from a single cylinder compression ignition engine (13.3 compression ratio) that was converted to natural-gas port fuel injection spark-ignition operation. Engine dynamometer tests investigated several spark timings, equivalence ratios, and engine speeds, which were also used as model inputs. While building the model it was found that adding the intake pressure as another model input improved model efficiency.