Automotive Science and Engineering
Year:2024 | Volume:14 | Issue:4|Papers Count:6

This paper presents an efficient dynamic programming method in order to examine the problem of optimal power management of hybrid electric vehicle (HEV) powertrains and compares its performance with a rule-based method. Since dynamic programming is a trajectory based optimization algorithm and provides a globally optimal solution, it can be used as a benchmark for assessment of other control strategies. However, a major limitation of this method is its extreme computational load which is known as the curse of dimensionality. The computation time and the memory requirements increase exponentially with the increase of states and inputs. In this paper, a novel approach is used to decrease the total computation load and shows how this improvement can provide more accurate results.

The engine mounting bracket is connected to the engine on one side and to the car body on the other side. The engine mounting bracket should be designed in such a way to prevent the transmission of vibrations from the body to the engine and vice versa. In addition, one of the tasks of the engine mounting bracket is to bear the weight of the engine and the dynamic and vibrational loads caused by the movement of the car on the road. The engine mounting bracket are generally designed in such a way that they have sufficient fatigue life in a defined range of cyclic forces and fail in the range of high forces caused by an accident in order to minimize the level of damage to the vehicle and passengers. This research will investigate the effect of manufacturing parameters on the fatigue behavior of the aluminum engine mounting bracket. High-cycle fatigue test was taken from the prototypes and based on the results of this test, the prototype was considered unsafe.  Therefore, in order to improve the produced part, by removing the factors that cause weakness in the part and strengthening the area in front of the engine mounting bracket, the secondary sample of the engine mounting bracket was produced, but due to the high costs of re-fatigue testing, radiographic test was done of the reinforced areas before testing. Then, fatigue test was taken from the secondary sample. The test results of the modified sample were within the acceptable range.

The transition from traditional internal combustion engine vehicles to electric vehicles is in progress. With their high energy density, low self-discharge rates, long cycle life, and absence of memory effects, lithium-ion batteries have become the primary power source for alternative vehicles. Throughout the battery's lifespan, its performance or health gradually deteriorates due to irreversible physical and chemical changes. Depending on the specific aging mechanisms, a battery may lose capacity or face increased internal resistance. Growing awareness of the importance of environmental protection and the potential implications associated with products and services has spurred interest in developing methods to better understand and address these impacts. Life cycle assessment is a method used to examine the environmental effects associated with all stages of product production. This study compares the operational conditions of an electric vehicle equipped with both new and old battery packs. The performance difference indicates that the vehicle with the aged battery has 17% less capacity, operates over 20% weaker in range, and its ohmic resistance increases by up to 150%. From a well-to-wheel perspective, using an electric vehicle with an old battery could result in a 2% increase in carbon dioxide emissions, reaching 56.638 g CO₂ equivalent per kilometer.

This study explored the impact of Super P on the specific capacity of MXene-based rechargeable Li-O₂ batteries. It was found that increasing the Super P ratio from 10% to 30% significantly improved the specific discharge capacity of the lithium-oxygen battery, rising from 396 mAh g⁻¹ to 1116 mAh g⁻¹ during the first cycle at a current density of 100 mA g⁻¹. To characterize the structure of the synthesized MXene, analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized. The electrochemical performance of the fabricated electrodes was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The findings indicate that the synergistic interaction between MXene and Super P contributes to the enhanced capacity of the fabricated cell.

Lithium-ion batteries hold great promise for addressing environmental and energy challenges, driving their increased adoption in electric vehicles. Their advantages include stability, high energy density, low self-discharge, and long lifespan. However, both high and low temperatures pose significant challenges. High temperatures can lead to thermal runaway and safety hazards such as short circuits and explosions, while low temperatures can promote the formation of lithium dendrites, resulting in degradation and performance issues. To mitigate these thermal challenges, phase change materials (PCMs) have emerged as a promising solution for battery thermal management systems (BTMS). This review provides a comprehensive overview of PCMs and their application in BTMS. We categorize PCMs used in BTMS based on their modified filler materials and functionalities, including carbon-based (carbon fiber-PCM composites, carbon nanotube-PCM composites, and expanded graphite-PCM composites), metal foam, metal mesh, and organic and inorganic materials. Both inorganic and carbon-based materials can serve as highly thermally conductive encapsulants and fillers for PCMs. Finally, we present a thorough review of recent research on the thermal properties of modified PCMs and their impact on BTMS performance, including a detailed discussion of PCM performance metrics and selection criteria.

One of the most important aspects of designing passenger cars is the engine cooling. This process would significantly affect the vehicle performance. This study has been conducted both theoretically and experimentally to reveal the influences of different involved parameters of cooling. The current research is implemented in order to examine the effects of 2-speed radiator fan utilization rather than the 1-speed type. For this aim, the new modified fan is considered and the experimental data are obtained to compare the results with those of the old one. Additionally, the effects of parameters such as ECU strategy, radiator fin density as well as the radiator plate geometrical properties are considered in the analysis. As a prominent result, the experimental results show a substantial effect of considering 2-speed radiator fan and choosing a better strategy for ECU on the cooling performance in the vehicle. The experimental results show that employing 2-speed fan instead of single-speed and 900 fin/m fin density instead of 780 fin/m decreases coolant outlet temperature of radiator by 6.1% and 7.1% in the same condition, respectively.