Automotive Science and Engineering
Volume:11 Issue: 2, Spring 2021

Reactivity control compression ignition (RCCI) engines have demonstrated high-efficient and clean combustion but still suffer from ringing operation at upper load and production of unburned hydrocarbon (uHC) and carbon monoxide (CO) emissions at lower load. In this study, statistical analysis and experimental testing were conducted to consider the effects of input parameters such as intake temperature (Tin), equivalent ratio (Φ) and engine speed on emissions, combustion noise and performance of a 0.5 liter RCCI engine using response surface method (RSM) with the aim to minimize emissions and combustion noise and to maximize parameters of performance. The developed models for measured responses like uHC, CO, nitrogen oxides (NOx) and calculated responses such as indicated mean effective pressure (IMEP) and combustion noise level (CNL) were statistically considered to be significant by analysis of variance (ANOVA). Interactive effects between Tin, Φ and engine speed for all operating points were analyzed by 3-D response surface plots. The results from this study indicated that at optimum input parameters, the values of uHC, CO, NOx, IMEP and CNL were found to be 90.3 (ppm), 106.8 (ppm), 248.2 (ppm), 11.7 (bar) and 87 (db), respectively. The models were validated by confirmatory tests, indicating the error in prediction less than 5%.

This paper presents low cycle fatigue (LCF) life prediction of an engine exhaust manifold. First Solidworks software was used to model the exhaust manifolds. Then Ansys Workbench software was used to determine stress and fatigue life based on Morrow and Smith-Watson-Topper (SWT) approaches. Thermal fatigue (TMF) of the engine components easily happens due to excessive temperature gradient and thermal stress. Modern exhaust systems must withstand severe cyclic mechanical and thermal loads throughout the whole life cycle. The numerical results showed that the temperature and thermal stresses have the most critical values at the confluence region of the exhaust manifolds. This area was under low cycle fatigue. After several cycles the fatigue cracks will appear in this region. The results of the finite element analysis (FEA) correspond with the experimental tests, carried out in references, and illustrate the exhaust manifolds cracked in this region. Finite element (FE) simulation proved a close correlation between Morrow and SWT criterions results. The lifetime of this part can be determined through finite element analysis instead of experimental tests.

This paper introduces a new configuration of ladder chassis containing a set of linear wave springs to improve the lateral stability of road vehicles. The governing equations for lateral stability of the ladder frame equipped with linear wave springs were derived. In order to investigate this new system a unit base of the ladder frame equipped with linear wave springs and a typical ladder frame were modeled using FEM methods (ABAQUS) with the same size conditions. This comparative study is utilized to validate the derived equations and also to compare the effectiveness of the new designed system with typical ladder frames. Results indicate that the new system has considerably improved the lateral stability of the vehicle during road transportation and also noticeably decreased the stress on the side and cross members.

In this study, a new micro gas turbine engine is presented. The effect of inlet air cooling on the performance of the micro gas turbine engine by changing the parameters such as the temperature difference between the inlet air temperature (IAT) based on ISA (International Society of Automation) standard and turbine inlet temperature (TIT) has been investigated. then, an Optimization is done base on the Genetic Algorithm with two separate objectives, SNOx minimization, and Thermal efficiency maximization, separately. The thermal efficiency and specific consumption of the optimized cycle based on the thermal efficiency are compared with the XU7/L3 internal combustion engine to produce the output power of 64.57 KW. Results show by adding a cooling system to the micro gas turbines to cool the inlet air with the coefficient performance of 2 and 4 increased the thermal efficiency by about 11.37% rather than base mrio gas turbine engine Eventually, the proposed micro gas turbine engine is more efficient than the XU7/L3 internal combustion engine. so It can be understood that micro  GT is one of the best substitutes for the internal combustion engine in the new vehicle age just by adding the cooling system.

HCCI engines have become the attention of research lately due to their advantages in reducing the emissions level, and their fuelling ability with alternative fuels. For this purpose, a single cylinder diesel engine with a port fuel injector and heated intake air were used to operate the HCCI engine at 2700 rpm using four different blends of POB biodiesel. The parameters varied for the study were different λ and intake air temperature. When using diesel fuel on HCCI mode, it is found that the engine power, torque, and BTE are lower and fuel consumption is higher compared to conventional Compression Ignition Direct Injection (CIDI) mode. The in-cylinder pressure pattern for HCCI mode shows that the combustion is advanced, and the in-cylinder pressure peak is higher at rich mixture compared to CIDI mode. The in-cylinder pressure decreases in the case of higher amount of biodiesel. Combustion intensity for biodiesel fuel is lower, which affects the heat release rate, whereas a high intake temperature triggers the combustion easily, enhances the fuel mixture auto-ignition proses. Increasing the amount of biodiesel will increase the NOx emissions insignificantly, however it is still lower than that of CIDI. POB based biodiesel improved the emissions of HCCI engines.

In this paper, an optimized insulator for sound packaging of the vehicle dash panel is proposed. The combination of the micro perforated panel and porous layers has been selected to insulate the dash panel of a vehicle.  The main advantages of the mentioned combination are light weight and various tunable parameters in comparison with other insulators. These provide significant flexibility to achieve an optimal performance for the noise attenuation of the vehicle cabin. Therefore, the parameters of the selected sound package have been optimized in order to achieve suitable sound absorption in a selected frequency range. Furthermore, the Genetic Algorithm (GA) is used to optimize the parameters. It can achieve more reliable and more accurate outcomes compared to the conventional method.  Full vehicle SEA (Statistical Energy Analysis) simulations are used to evaluate the optimized sound package. The results indicate that the optimized concept has maximum sound absorption capability.  Consequently, the proposed sound package improves the vehicle's engine noise reduction by 5 dB in comparison with un-optimized sample in mid and high frequency ranges.

Diesel engines are the most trusted sources in the transportation industry. They are also widely used in the urban transportation system. Most pollutants are related to these engines. Therefore, it is important to increase the performance and reduce exhaust emissions of these engines. Alternative fuels are key to meeting upcoming targets.
An experimental and numerical study was performed to investigate the effect of diesel fuel and hydrogen addition to diesel fuel from 0 to 30% on performance and exhaust emissions. Also in this research for changing diesel fuel, an indirect injection engine converted to direct injection engine. The simulation study was conducted by Star cd codes and experimental investigation was carried out on a diesel engine (Perkins 1103A-33TG1), three- cylinders, and four-stroke with maximum engine power 72.3hp at 1800 rpm. The results from this study showed that the increase of hydrogen to diesel fuel improves the thermal efficiency, resulting in lower specific fuel consumption. Also, the results showed that adding hydrogen until 30%, the cylinder pressure increase by about 9% and occurred the delay of peak pressure about 8 degrees of a crank angle compared to diesel fuel. The other obtained results in emission with 30%H2+Diesel showed the soot emission reduced 11.3%, HC and CO reduced nearly 36%, but NOx increased by about 8.3% due to high combustion temperature.