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2,5-dimethylfuran (DMF) is currently regarded as a potential alternative fuel to gasoline due to the development of new production technology. In this paper, the spray characteristics of DMF and its blends with gasoline were studied from a high pressure direct injection gasoline injector using the shadowgraph and Phase Doppler Particle Analyzer (PDPA) techniques, This includes the spray penetration, droplet velocity and size distribution of the various mixtures. In parallel commercial gasoline and ethanol were measured in order to compare the characteristics of DMF. A total of 52 points were measured along the spray so that the experimental results could be used for subsequent numerical modeling. In summary, the experimental results showed that DMF and its blends have similar spray properties to gasoline, compared to ethanol. The droplet size of DMF is generally smaller than ethanol and decreases faster with the increase of injection pressure.

Fuel quality has a significant influence on the combustion engine operation. In recent years the increasing concerns about environmental protection, energy saving, energy security and the requirements of protecting fuel injection and aftertreatment systems have been major driving forces for the Chinese fuel specification evolution. The major property changes in the evolution of Chinese national gasoline and diesel standards are introduced and the reasons behind these changes are analyzed in this paper. The gasoline fuel development from State I to State VI-B involved a decrease of sulfur, manganese, olefins, aromatics and benzene content. The diesel fuel quality improvement from State I to State VI included achieving low sulfur fuels and a cetane number (CN) increase. Provincial fuel standards, stricter than corresponding national standards, were implemented in economically developed areas in the past.

Due to the rapid development of road infrastructure and vehicle population in China, the fuel consumption and emission of on-road vehicles tested in China World Transient Vehicle Cycle (C-WTVC) cannot indicate the real driving results. But the test results in China Heavy-duty Commercial Vehicle Test Cycle-Coach (CHTC-C) based on the road driving conditions in China are closer to the actual driving data. In this paper, the model for predicting the performance of heavy-duty vehicles is established and validated. The fuel consumption and NOx emission of a Euro VI heavy-duty coach under C-WTVC and CHTC-C tests are calculated by employing the developed model. Furthermore, the fuel consumption of the test coach is optimized and its sensitivity to the driving factors is analyzed.

A computational fluid dynamics (CFD) guided design optimization was conducted for the piston bowl geometry for a heavy-duty diesel engine. The optimization goal was to minimize engine-out NOx emissions without sacrificing engine peak power and thermal efficiency. The CFD model was validated with experiments and the combustion system optimization was conducted under three selected operating conditions representing low speed, maximum torque, and rated power. A hundred piston bowl shapes were generated, of which 32 shapes with 3 spray angles for each shape were numerically analyzed and one optimized design of piston bowl geometry with spray angle was selected. On average, the optimized combustion system decreased nitrogen oxide (NOx) emissions by 17% and soot emissions by 41% without compromising maximum engine power and fuel economy.

The combustion characteristics and soot emissions of three types of fuels were studied in a high pressure and temperature vessel. In order to achieve better volatility, proper cetane number and high oxygen content, the newly designed WDEP fuel was proposed and investigated. It is composed of wide distillation fuel (WD), PODE3-6 mixture (PODEn) and ethanol. For comparison, the test on WD and the mixture of PODEn-ethanol (EP) are also conducted. OH* chemiluminescence during the combustion was measured and instantaneous PLII was also applied to reveal the soot distribution. Abel transformation was adopted to calculate the total soot of axisymmetric flame. The results show that WDEP has similar ignition delays and flame lift-off lengths to those of WD at 870-920 K. But the initial ignition locations of WDEP flame in different cycles were more concentrated, particularly under the condition of low oxygen atmosphere.

Multi-mode combustion is an ideal combustion strategy to utilize HCCI for internal combustion engines. It combines HCCI combustion mode for low-middle load and traditional SI mode for high load and high speed. By changing the cam profiles from normal overlap for SI mode to the negative valve overlap (NVO) for HCCI mode, as well as the adjustment of direct injection strategy, the combustion mode transition between SI and HCCI was realized in one engine cycle. By two-step cam switch, the throttle action is separated from the cam action, which ensures the stabilization of mode transition. For validating the feasibility of the stepped switch, the influence of throttle position on HCCI combustion was carefully studied. Based on the research, the combustion mode switch was realized in one engine cycle; the whole switch process including throttle action was realized in 10 cycles. The entire process was smooth, rapid and reliable without any abnormal combustion such as knocking and misfiring.

Soot emissions in the combustion process of diesel engines are greatly harmful to the environment and human health. Consequently, there is large interest and great efforts in decreasing soot emission from diesel engines to meet the increasingly stringent emission standards. The mechanisms of soot formation and oxidation so far have not been well understood. Laser induced incandescence (LII) is particularly suited to measure the instantaneous spatial distribution of the soot volume concentration, which can offer much needed detailed information of soot distribution for better understanding of soot formation and oxidation. In this paper, a two-color laser induced incandescence (2C-LII) technique was implemented for measuring absolute soot volume fraction in a laminar diesel fuel diffusion flame.

Urea Selective Catalytic Reduction (SCR) has been proven to significantly reduce NOx emissions from diesel engines. The thermal decomposition of urea, which forms the ammonia as the reactant, has a crucial effect on the performance and durability of the NOx-SCR system. The incomplete thermal decomposition of urea not only reduces the NOx conversion ratio and increases the ammonia slip, but also leads to deposit formation on the catalyst surface, which will block the pore and the active sites of the catalyst and then decreases the durability of the SCR systems. In this paper, the urea thermolysis was measured using the Thermal Gravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Then, the performance of the SCR systems under different injection parameters of the Urea-water solution was investigated on a diesel engine test bench. Finally, the deposits on the catalyst were also analyzed using TGA and FTIR.

Biodiesel is an alternative, renewable, clean fuel, which can effectively reduce emissions from diesel engines. However, the effects of biodiesel on engine emissions vary due to the difference in source. In this paper, performance of five different biodiesels was studied: CME, SME, RME, PME and WME. Engine power, fuel consumption, gaseous emissions and PM, DS and none soot fraction (NSF) were investigated in a Cummins ISBe6 Euro III diesel engine fueled with five biodiesels respectively and compared with the diesel fuel. Results revealed that using different biodiesels resulted in PM reductions ranging from 53% to 69%, which included DS reduction ranging from 79% to 83%. Observations showed that fuel oxygen content and viscosity had obvious effects on DS. Higher oxygen content biodiesels produced less DS at high load while lower viscosity biodiesels produced less DS at low load.

Beijing will implement the 4th stage emission regulations (equivalent to Euro IV) in 2008 ahead of other provinces or cites in China. Beijing Environmental Protection Bureau (EPB) organized petroleum corporations, automobile and engine manufactories as well as research institutes to test the adaptability of the fuels from Chinese refineries to the modern vehicles or engines on the road running conditions in China. In this paper, the effects of diesel fuel quality on combustion and emission of a Euro IV heavy-duty diesel engine as one part of the program were studied to provide technical data to stipulate the feasible diesel fuel standard, which should guarantee modern vehicles or engines to meet the 4th stage regulations. Eight kinds of diesel fuels with different properties, such as cetane number, distillation temperature (T90) and sulfur content, were tested on a Euro IV Cummins heavy-duty diesel engine with urea SCR after-treatment.

According to China's “oil-poor, gas-litte, coal-rich” structure of energy resources, to promote the development of coal-based methanol fuel as a clean alternative to gasoline and diesel fuel is one of the most realistic options. So the adaptability of methanol gasoline blend fuel used in the gasoline engine and vehilce should be investigated. Engine load performance, engine out emission, air fuel ratio variation and combustion characteristics were tested in a PFI Euro III gasoline engine using gasoline, M10, M15, M20, M30 as fuel without any modification of the engine. Air fuel ratio, light-off temperature and load characteristics of catalystic conversion coefficient were also investigated. And effects of methanol content on fuel consumption and vehicle out emissions of a Euro - vehicle are analyzed.

On the basis of modular pulse converter (MPC) exhaust system the authors present a new swirl exhaust system. Structural parameters on the swirl exhaust system and MPC system for N8160ZC diesel engine were calculated by a mathematical optimum method, and the two systems were tested under the same engine operation for comparison. Experimental results show that the swirl exhaust system has a better engine performance under most of the operating conditions than MPC system, but worse under the low-speed and part-load conditions. In order to understand the mechanism of this swirl exhaust system well, a three-dimensional particle dynamic analyzer (3D-PDA) was utilized to measure the steady turbulent airflow in a swirl three-branched model. The computational fluid dynamics (CFD) code KIVA was modified to simulate the flows. Computational results are in good agreement with measuring ones and reveal the swirl flow behavior in the junction.

With increasingly stringent requirements and regulations related to particulate matter(PM) emissions, manufacturers are paying more and more attention to emissions from gasoline direct injection(GDI) engines. The present paper proposes an improved two-step soot model. The model is applied in the Kiva-Chemkin program to simulate the processes of spray impinging, fuel mixture preparation, combustion and soot formation in a typical turbocharged downsized GDI engine. The simulation results show that soot formation in the GDI engine is attributed to non-uniform distribution of the air-fuel mixture and pool fire of wall film in the cylinder. Under homogeneous mode, increasing the injection advance angle can optimize fuel atomization and improve air-fuel mixing, thus reducing soot formation. However, an excessive injection advance angle may cause spray to impinge on the cylinder wall and this will sharply increase the soot emission.

In diesel engines, valve avoiding pit (VAP) is often designed on the top of the piston in order to avoid the interference between the valves and the piston during the engine operation. With the continued application of the downsized or high power density diesel engines, the depth of VAP has to be further deepened due to increased valve lift for more air flow into and out of the cylinder and decreased piston top clearance for less HC/CO and soot emissions. The more and more deepening of VAP changes the combustion chamber geometry, the top clearance height and the injector relative position to the piston crown. In this paper, a 3-D in-cylinder combustion model was used for a heavy duty diesel engine to investigate the effects of the depth of VAP on combustion process and emissions. Five depths of VAP were designed in this study. In order to eliminate the influence of compression ratio, the piston clearance height was adjusted for each VAP depth to keep the same compression ratio.

Due to increasingly stringent emission and fuel consumption regulations, diesel engines for vehicle are facing more and more technical challenges. Engine downsizing technology is the most promising measures to deal with these challenges at present. With the enhancement of power density, a small engine displacement with a high turbocharging technique becomes popular. In order to increase the intake mass flow rate on a downsizing diesel engine, the tilting axis of intake valve was chosen to enlarge the intake valve diameter and decrease the arc radius of intake ports. Thus cylinder head had to be redesigned to meet this demand. Geometry of cylinder head made a notable effect in organization of in-cylinder flow, fuel-air mixing quality and further combustion characteristics. 3-D CFD was a convenient and economical tool to explore effects of geometry of cylinder head on the combustion process.

2, 5-Dimethylfuran (DMF) has been receiving increasing interest as a potential alternative fuel to fossil fuels, owing to the recent development of new production technology. However, the influence of DMF properties on the in-cylinder fuel spray and its evaporation, subsequent combustion processes as well as emission formation in current gasoline direct injection (GDI) engines is still not well understood, due to the lack of comprehensive understanding of its physical and chemical characteristics. To better understand the spray characteristics of DMF and its application to the IC engine, the fuel sprays of DMF and gasoline were investigated by experimental and computational methods. The shadowgraph and Phase Doppler Particle Analyzer (PDPA) techniques were used for measuring spray penetration, droplet velocity and size distribution of both fuels.

A catalyst surfaced on Ag/Al2O3 substrate for the selective catalyst reduction (SCR) of NOx by ethanol was evaluated in a diesel engine, and the effect of the catalyst on the reduction of NOx from the diesel engine under the EURO III ESC test modes was also investigated. The reductant injecting device was designed by means of computational fluid dynamics (CFD) analysis, and the engine test bench including the reductant injection system for the evaluation of the NOx-SCR catalyst performance was established. On the bench, the SCR catalyst with the ethanol reductant was tested at different temperatures and space velocities (SV), and integrated with an oxidation catalyst to reduce the diesel exhaust emissions of NOx, HC and CO. Under the conditions of the SV=30,000 h-1 and the exhaust temperature range of 350∼420°C, the NOx conversion efficiency is high over 90% and low beyond the temperature range.

A feasible method was developed to reconstruct the three-dimensional flame surface of SI combustion based on 2D images. A double-window constant volume vessel was designed to simultaneously obtain the side and bottom images of the flame. The flame front was reconstructed based on 2D images with a slicing model, in which the flame characteristics were derived by slicing flame contour modeling and flame-piston collision area analysis. The flame irregularity and anisotropy were also analyzed. Two different principles were used to build the slicing model, the ellipse hypothesis modeling and deep learning modeling, in which the ellipse hypothesis modeling was applied to reconstruct the flame in the optical SI engine. And the reconstruction results were analyzed and discussed. The reconstruction results show that part of the wrinkled and folded structure of the flame front in SI engines can be revealed based on the bottom view image.

Downsizing as a main-stream technology was widely used for design of future diesel engines in order to meet the increasingly stringent demands of emissions regulation and reduction of CO2 production. Design of intake system faces a considerable challenge accordingly. Discharge coefficient and swirl ratio as two main factors of intake port design have been widely investigated by researchers. However, these two parameters indicate a trade-off relationship. Therefore, it is difficult for a classical intake system to achieve a good balance between sufficient air charge and decent air-fuel radial mixing quality. A 1 L twin-intake-port single-cylinder diesel engine was studied in this paper. A swirl control valve designed to adjust the effective flow area of the filling port, was installed between the intake manifold and the intake filling port in order to achieve variation of swirl ratio. And there is no control valve for the intake spiral port.

Computational Fluid Dynamics (CFD), as an effective analytical tool, has been applied at China North Engine Research Institute (CNERI) for combustion chamber design and combustion system optimization on a V8 heavy -duty diesel engine in order to meet increasingly stringent emission targets. The design of combustion system involves great number of parameteric optimizations such as the number of nozzle holes, the spray angle, the swirl ratio and the piston bowl shape. 3-D CFD was a convenient and cheap tool to explore the effects of all these parameters to the engine performance, compared with extensive hardware testing. 1-D modeling was used to set up boundary conditions at intake valve closure for 3-D CFD modeling during the closed-cycle. AVL FIRE software with a widely used combustion model, ECFM-3Z model, was used for 3-D simulation. Two sets of nozzle holes, four spray angles and three swirl levels were utilized and optimized under rated power.