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Spray-wall impingement is an unavoidable physical process in homogeneous charge compression ignition (HCCI) diesel engines using early injection strategy which is the main source for the hydrogen carbon (HC) and monoxide (CO) emissions. Dimethyl ether (DME) is a potential fuel additive to decrease HC and CO emissions due to its higher oxygen content. However, issues relating to structural design and early injection timing mean spray-wall impingement still occurs when using the diesel-DME blended fuels, which directly affect the fuel-air mixture formation in the near wall region and further influence the emission characteristics. The better understanding for the effects of spray-wall impingement parameters on fuel-air mixture formation in near wall region for diesel-DME blended fuels is helpful for the improvement of HC and CO emissions for HCCI diesel engines.

The weight of an exhaust system on a modern vehicle is increasing because of all kinds of reasons, like engine power's increasing, more catalysts for emission control and more NVH (Noise, Vibration and Harshness) performance requirements. After the engine starting, the exhaust system was not only bearing a cyclical load from the engine, which mainly causing the vibration of the exhaust system, but also the loads from the road, which was transferred through the wheels, the suspension system and the body. Because the exhaust system always worked in these bad conditions, its structural strength, durability and life-time were analyzed in the paper, by numerical simulation and physical correlation. By discretizing the exhaust system's CAD model, a finite element model was built. After restrict the finite element model as it in a real load condition, complete the structure stress analysis and Fatigue analysis of exhaust system's hanger with FEA analysis tools.

Fuel cell vehicle and battery electric vehicle are two environmentally benign vehicle technology types possibly meeting the zero-emission regulations in the future. The premise is they can achieve parity with conventional vehicle both environmentally and economically. Besides, it is necessary to distinguish which technology is more suitable in China's current and future context. This paper compares their cost-effectiveness for reducing greenhouse gas emissions, examining the life-cycle greenhouse gas emissions of conventional gasoline vehicle, battery electric vehicle and fuel cell vehicle in China's energy context under three different scenarios. The results indicate that under the 500km drive range, fuel cell vehicles are less competitive than battery electric vehicles currently. Fuel cell vehicles generate much more greenhouse gas emissions than battery vehicles and conventional gasoline vehicles.

The homogeneous charge, compression-ignition (HCCI) combustion process has the potential to significantly reduce NOx and particulate emissions, while achieving high thermal efficiency and the capability of operating with a wide variety of fuels. This makes the HCCI engine an attractive technology that can ostensibly provide diesel-like fuel efficiency and very low emissions, which may allow emissions compliance to occur without relying on lean aftertreatment systems.

A segment of steel tube with the inner diameter of 60 mm and length of 100 mm was fixed between the intake manifold and cylinder head in a direct injection natural aspirated diesel engine. The surface of the tube could be heated to be above 400 °C by the heater enwrapped outside within several minutes under the power less than 600 W. The tip of an injector traditionally used for in-cylinder diesel direct injection was extended to the axis of the tube. The diesel sprays could impinge onto the hot inner surface of the tube and atomize quickly if the temperature of the tube was high enough. Then the fuel-air mixture would be sucked into the cylinder, and HCCI combustion could be fulfilled. The vaporization ratio of the impinged diesel sprays was estimated by fuel consumption, intake air flux and excess air coefficient (λ) calculated from the volumetric concentration of O2, CO2 and CO emissions. The NOx emission was always very low.

Future clean combustion engines tend to increase the cylinder charge to achieve better fuel economy and lower exhaust emissions. The increase of the cylinder charge is often associated with either excessive air admission or exhaust gas recirculation, which leads to unfavorable ignition conditions at the ignition point. Advanced ignition methods and systems have progressed rapidly in recent years in order to suffice the current and future engine development, and a simple increase of energy of the inductive ignition system does not often provide the desired results from a cost-benefit point of view. Proper design of the ignition system circuit is required to achieve certain spark performances.

This paper presents an investigation of cold starts based on a cycle-by-cycle control strategy in an LPG EFI engine. Experiments were carried out in a four-stroke, water-cooled, single cylinder, 125cc SI engine with an EFI system. Effects of the first injection pulse width and the first combustion cycle on the characteristics of the cold-start were analyzed based on the histories of transient engine speeds and cylinder pressures. The study focuses on how to realize the controllable ignition cycle and the single-cycle and multi-cycle combustions were tested based on the single starting injection pulse width. Test results show that the first combustion cycle has an important effect on HC emission and combustion stability of following cycles at cold-start. The injection pulse width is the key factor determining the characteristics of an ignition cycle during the cold-start.

Hydrogen-fueled Argon Power Cycle engine is a novel concept for high efficiency and zero emissions, which replaces air with argon/oxygen mixtures as working fluid. However, one major challenge is severe knock caused by elevated in-cylinder temperature resulting from high specific heat ratio of Argon. A typical knock-limited compression ratio is around 5.5:1, which limits the thermal efficiency of Argon Power Cycle engines. In this article, preliminary experimental research on the effect of water direct injection at late exhaust stroke is presented at 1000 r/min with IMEP ranging from 0.3~0.6 MPa. Results show that, with temperature-reducing effect of water evaporation, knock is greatly inhibited and the engine can run normally at a higher compression ratio of 9.6:1. Water injected at the exhaust stroke minimizes its reducing effect on the specific heat ratio of the working fluid during the compression and expansion strokes.

In order to meet the ever more stringent demands on the CO2 emission reduction, downsized modern gasoline engine with highly boosted turbo charger meets new challenges such as super knock and pre-ignition, which will influence the engine combustion efficiency, smooth operation and even cause mechanical failure. A spark plug type ion current detection sensor was used in a 1.8L turbo charged gasoline engine. The ion-current wave signal differed greatly under different engine operating conditions such as without knock, with knock of different knock intensities. The frequency spectrum of ion-current was also studied, by the method of discrete Fourier transform (DFT). In knocking cycles, there were fluctuations of frequency 8-13 kHz both in the combustion pressure signal and in the ion current signal, proving the existence of knock information.

Based on a 125cm3 single cylinder SI engine, the designated idle speed was controlled by adjusting of cycle ignition advance angle. By analyzing the effects of different idle speed and throttle open position on three way catalyst (TWC) light-off time and conversion efficiency of HC and CO emissions, combined with the corresponding total HC and CO emissions level, the optimum idle speed and throttle open position at engine's warm-up phase were found by the matching optimum. The present method for engine control strategy is helpful to optimize the warm-up phase emission levels in SI engine with LPG fuel.

In this paper a method of misfiring control in current cycle at engine start is presented. With this novel method, the high HC emissions of gasoline engine employed in traditional or hybrid electrical vehicles will be avoided. By the feedback of ion current signal, misfire phenomenon is identified within 30 degrees crank angle after spark plug ignited. Then, the ignition coil will be recharged and the plug sparked again to promote air fuel mixture oxidation and deplete the unburned hydrocarbon produces in exhaust gas. On the other hand, too late ignition will not always result in normal combustion, a kind of reaction similar with slow oxidation also occurs in such case.

The effect of a new exhaust catalyst system consisting of the traditional three way catalyst converter (TWC) and adsorber-reduction catalyst converter along the emission systems has been investigated in this research under different schemes of catalyst converter arrangement and different ranges of engine speed and engine load. The effect on BSFC (Brake Specific Fuel Consumption) of a lean burn gasoline engine has also been studied at the same time. The upstream placement of TWC ahead of the NOx Adsorber Catalyst has been selected, which is corresponding to the highest NOx converting efficiency. The effect of engine speed on the exhaust emission and BSFC is related to absolute time and the ratio of lean burn time to rich burn time. Engine load is the major factor in affecting exhaust emission characteristics and BSFC of lean burn gasoline engine.

Ammonia is employed as the carbon-free fuel in the future engine, which is consistent with the requirements of the current national dual-carbon policy. However, the great amount of NOx and unburned NH3/H2 in the exhaust emissions is produced from combustion of ammonia and is one kind of the most strictly controlled pollutants in the emission regulation. This paper aims to investigate the NOx and unburned NH3/H2 generative process and emission characteristics by CFD simulation during the engine combustion. The results show that the unburned ammonia and hydrogen emissions increase with an increase of equivalence ratio and hydrogen blending ratio. In contrast, the emission concentrations of NOx, NO, and NO2 decrease with the increasing of equivalence ratio, but increase with hydrogen blending ratio rising. The emission concentration of N2O is highly sensitive to the O/H group and temperature, and it is precisely opposite to that of NO and NO2.

Ammonia is used as the carbon-free fuel in the engine, which is consistent with the requirements of the current national dual-carbon policy. However, the great amount of NOx in the exhaust emissions is produced after combustion of ammonia and is one kind of the most tightly controlled pollutants in the emission regulation. Nitrous Oxide (N2O) is a greenhouse gas with a very strong greenhouse effect, so that the N2O emissions needs to be paid close attention. In this paper, the CFD simulation of the N2O formation and emission characteristics during combustion is carried in the ammonia/hydrogen fueled pre-chamber jet ignition engine.

The argon power cycle engine, which uses hydrogen as fuel, oxygen as oxidant, and argon other than nitrogen as the working fluid, is considered as a novel concept of zero-emission and high-efficiency system. Due to the extremely high in-cylinder temperature caused by the lower specific heat capacity of argon, the compression ratio of spark-ignition argon power cycle engine is limited by preignition or super-knock. Compression-ignition with direct-injection is one of the potential methods to overcome this challenge. Therefore, a detailed flammability limit of H2 under Ar-O2 atmosphere is essential for better understanding of stable autoignition in compression-ignition argon power cycle engines.

Plug-in hybrid electric vehicles (PHEVs) provide significantly improvement in fuel economy over conventional vehicles as well as reductions in greenhouse gas and petroleum. Numerous recent reports regarding control strategy, power train configuration, driving pattern, all electric range (AER) and their effects on fuel consumption and electric energy consumption of PHEVs are reported. Meanwhile, the control strategy for engine start-stop and mileage between recharging events from the electricity grid also has an important influence on the petroleum displacement potential of PHEVs, but few reports are published. In this paper, a detailed simulation model is set up for a plug-in series hybrid electric vehicle (PSHEV) employing the AVL CRUISE. The model was employed to predict the AER of the baseline PSHEV using rule-based logical threshold switching control strategy.

GDI engine has gained much popularity in vehicle market with its high thermal efficiency. However, because of higher particulate emissions, it becomes harder for GDI engines to fulfill the iteration of emission regulations in various countries. As a result, Gasoline Particulate Filter (GPF) has received more and more attention and applications. It is important to study the particulate emission and GPF performance especially for transient cycles. With a self-designed test bench with burner named Exhaust Gas Simulator, a transient control strategy to simulate the exhaust state of the WLTC cycle has been developed and achieved a fast and stable ash accumulation rate. Three levels of ash loading, in terms of 0g/L, 5g/L and 35g/L, were accumulated on respective GPF for different aging degrees with this test bench. The effect of ash loading on GPF performance was investigated.

Electric vehicles maintain the fastest development in China and undertake the responsibility of optimizing energy consumption and carbon emission in the transportation field. However, from the entire life cycle point of view, although electric vehicles have a certain degree of energy consumption and carbon emission reduction in the use phase, they cause extra energy consumption and carbon emission in the manufacturing phase, which weakens the due environmental benefits to some extent. The recycling of electric vehicles can effectively address the issue and indirectly reduce the energy consumption and carbon emission in the manufacturing phase. China is setting up the recycling system and strengthening regulation force to achieve proper energy consumption and carbon emission reduction benefits of electric vehicles. Under the current electric vehicle recycling technologies, China can reduce about 34% of carbon emission in electric vehicle manufacturing phase.

Compared with conventional vehicles, electric vehicles (EVs) offer the benefits of replacing petroleum consumption and reducing air pollutions. However, there have been controversies over greenhouse gas (GHG) emissions of EVs from the life-cycle perspective in China’s coal-dominated power generation context. Besides, it is in doubt whether the cost-effectiveness of EVs in China exceeds other fuel-efficient vehicles considering the high prices. In this study, we compared the life-cycle GHG emissions of existing vehicle models in the market. Afterwards, a cost model is established to compare the total costs of vehicles. Finally, the cost-effectiveness of different vehicle types are compared. It is concluded that the GHG emission intensity of EVs is lower than reference and hybrid vehicles currently and is expected to decrease with the improvement of the power grid.

A novel method is applied to analysis the autoignition phenomenon. Experiments on the study of autoignition characteristics of diesel fuel were carried out with a Controllable Active Thermo-Atmosphere Combustor. The results show that the method for autoignition studying of liquid fuel is of feasibility. Autoignition delay time and autoignition height from the nozzle increase with the coflow temperature decreasing and autoignition delay time changes sensitively under lower coflow temperature. Liftoff height of diesel spray flame decreases with the increasing of coflow temperature. Lower temperature causes higher variance of liftoff height. It might be speculated that there are two different mechanisms of flame stabilization that the lower lift-off heights flames are related to a balance between the flow velocity and flame speed while the higher lift-off heights flames are stabilized by the mixture autoignition.