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A Controllable Active Thermo-Atmosphere (CATA) Combustor enables the investigation of stabilization mechanisms in an environment that decouples the turbulent chemical kinetics from the complex recirculating flow. Previous studies on combustion of the low-pressure fuel jets in the Controllable Active Thermo-Atmosphere (CATA) showed non-linear effect of coflow temperature on autoignition delay and the randomness of autoignition sites. In this work, a diesel spray is injected into the CATA with the injection pressure at 20MPa from a single-hole injector and the autoignition and combustion process of the spray is recorded by a high-speed camera video. The multipoint autoignition of diesel spray is observed in the CATA and the subsequent combustion process is analyzed. The results show that autoignition phenomenon plays an important role in the stabilization of the lifted flames of diesel spray under low coflow temperature.

In this paper, a case study of Shanghai HEVs application and its effects on the social and environmental benefits are presented based on the multi views on the different aspects, such as, not only for the fuel consumption saving, but also emissions reduction and health effect, agriculture loss and cleaning cost. The results show that the potential benefits for the society from HEVs application are markedly with the increase of the ratio of HEV in the population of vehicle. Based on this, the policy to promote the HEV purchased by consumers is very important at the beginning of HEV into market.

Combustion and emission characteristics of diesel and biodiesel blends (soybean methyl ester) were studied in a single-cylinder Direct Injection (DI) engine at different loads and a constant speed. The results show that NOx emission and fuel consumption are increased with increasing biodiesel percentage. Reduction of smoke opacity is significant at higher loads with a higher biodiesel ratio. Compared with the baseline diesel fuel, B20 (20% biodiesel) has a slight increase of NOx emission and similar fuel consumption. Smoke emission of B20 is close to that of diesel fuel. Results of combustion analysis indicate that start of combustion (SOC) for biodiesel blends is earlier than that for diesel. Higher biodiesel percentage results in earlier SOC. Earlier SOC for biodiesel blends is due to advanced injection timing from higher density and bulk modulus and lower ignition delay from higher cetane number.

In this paper, the characteristics of performance and emissions of diesel and biodiesel blends are studied in a four-cylinder DI engine employing common rail injection system. The results show that engine output power is further reduced and brake specific fuel consumption (BSFC) increased with the increase of the blend concentration. B100 provides average reduction by 8.6% in power and increase by 11% in BSFC. With respect to the emissions, although NOx emissions were increased with increasing the blend concentration, the increase depends on the load. Filter smoke number is reduced with increasing the blend concentration. At the same time, NO, NO2 and other specific emissions are also investigated. In addition, difference of performance and emission between standard parameters of ECU and modified parameters of ECU is investigated for B10 and B20 based on same output power. The results show that NOx emission and FSN are still lower than baseline diesel.

The effects of biodiesel on the swelling of the elastomers and plastics and the corrosion of metals are studied by the immersion tests. The results indicate that biodiesels make little corrosion effect on aluminum, steel and little swelling impact on plastics, but a significant corrosion may be taken place on cooper and brass for some sourced biodiesels. For nitrile-butadiene rubber, the variation of swelling properties in biodiesels is slightly higher than that in diesel. For the non-diesel-resistant elatomers, the variation of swelling properties is lower than those in diesel. The production process and biodiesel source have an influence on the result of elastomer swelling and corrosion. The relationship between the impact of biodiesel on materials and biodiesels properties are also discussed.

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 swelling of ‘O’ rings of 3 typical rubbers (NBR, FKM, EPDM) and the corrosion of 2 typical copperish metal pieces (Copper, Brass) were investigated. The fuel samples included 14 kinds of biodiesels, 1 kind of diesel, and 4 kinds of blends respectively for 2 kinds of biodiesels. The changes in mass and size of ‘O’ rings were measured with an electronic balance and a vernier caliper. The surface corrosion of copperish metals was recorded with photos. It was found that the swelling of NBR in pure biodiesels were generally larger than those in diesel. The mass and size of FKM almost did not change in both pure biodiesels and diesel. The swelling of EPDM became less in pure biodiesels than that in diesel. When the blend ratios of biodiesels were less than 10%, the change rates in mass, inner diameter and section diameter of NBR, FKM and EPDM were similar between blended fuels and diesel.

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.

This paper presents a study of the influence of intake valve closing (IVC) timing on the performance of the high-speed spark ignition (SI) engine, such as the output of torque and power, fuel consumption and emissions. An electrically controlled Variable Valve Timing (VVT) system based on the variable working position belt extender was developed and its pro-type was successfully set up in a 5-valve, double overhead cam (DOHC) SI engine. Test results showed that the IVC timing plays an important role in increasing the power output, decreasing the fuel consumption and CO and HC emissions under both high- and low-speed conditions as compared to the fixed IVC timing. The control of intake valve closing timing is a simple and effective means to improve engine's performance.

An experimental study is presented on the evaporation of diluted droplet-laden two-phase jet flows within a heated air channel co-flow. In this study, n-heptane is pre-atomized by an ultrasonic nozzle to produce droplet cluster with a median diameter of about15μm, and a continuous cold air flow is applied to carry the fuel droplet cluster to emerge from a nozzle tube, producing a free turbulent jet of droplet stream. The droplet stream is then introduced as a central jet into a square-shaped channel with heated air co-flow for evaporation investigations. With flexibilities of the initial properties of droplet stream and surrounding conditions of channel flow, the axial evolution of droplet size is determined to characterize the evaporation behavior of n-heptane droplet stream under various boundary conditions. The equivalence ratios of droplet streams are varied by changing both the carrier-air flow rate and the fuel flow rate.

In order to investigate the impacts of recirculated exhaust gas temperature on gasoline engine combustion and emissions, an experimental study has been conducted on a turbocharged PFI gasoline engine. The engine was equipped with a high pressure cooled EGR system, in which different EGR temperatures were realized by using different EGR coolants. The engine ran at 2000 r/min and 3000 r/min, and the BMEP varied from 0.2MPa to 1.0MPa with the step of 0.2MPa. At each case, there were three conditions: 0% EGR, 10% LT-EGR, 10% HT-EGR. The results indicated that LT-EGR had a longer combustion duration compared with HT-EGR. When BMEP was 1.0 MPa, CA50 of HT-EGR advanced about 5oCA. However, CA50 of LT-EGR could still keep steady and in appropriate range, which guaranteed good combustion efficiency. Besides, LT-EGR had lower exhaust gas temperature, which could help to suppress knock. And its lower exhaust gas temperature could reduce heat loss. These contributed to fuel consumption reduction.

This research was concerned with the use of Exhaust Gas Recirculation (EGR) improving the fuel economy over a wide operating range in a downsized boosted gasoline engine. The experiments were performed in a 1.3-Litre turbocharged PFI gasoline engine, equipped with a Low Pressure (LP) water-cooled EGR system. The operating conditions varied from 1500rpm to 4000rpm and BMEP from 2bar to 17bar. Meanwhile, the engine’s typical operating points in NEDC cycle were tested separately. The compression ratio was also changed from 9.5 to 10.5 to pursue a higher thermal efficiency. A pre-compressor throttle was used in the experiment working together with the EGR loop to keep enough EGR rate over a large area of the engine speed and load map. The results indicated that, combined with a higher compression ratio, the LP-EGR could help to reduce the BSFC by 9∼12% at high-load region and 3∼5% at low-load region.

Research studies have suggested that changes to the ignition system are required to generate a more robust flame kernel in order to secure the ignition process for the future advanced high efficiency spark-ignition (SI) engines. In a typical inductive ignition system, the spark discharge is initiated by a transient high-power electrical breakdown and sustained by a relatively low-power glow process. The electrical breakdown is characterized as a capacitive discharge process with a small quantity of energy coming mainly from the gap parasitic capacitor. Enhancement of the breakdown is a potential avenue effectively for extending the lean limit of SI engine. In this work, the effect of high-power capacitive spark discharge on the early flame kernel growth of premixed methane-air mixtures is investigated through electrical probing and optical diagnosis.

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.

Spray behavior is regarded as one of main factors which influence engine performance, fuel consumption and emissions for diesel engine. In practice, spray characteristics from each orifice from a multi-hole nozzle are normally arranged symmetrically, while the hole-to-hole spray variation is unavoidable. This variation will cause spatial uneven distribution of spray and combustion degrade, which will be no longer inconsiderable in face of the more and more stringent emission rules. In this paper, two methods including spray macro-characteristics experiment and separated fuel mass measurement are employed to test the hole-to-hole spray variation of two six-hole symmetric VCO injectors of different brands, and experiments are operated under different conditions including different injection pressures, back pressures and injection durations.

The CO2 reduction request for automotive industry promotes the efforts on the engine thermal efficiency improvement. The goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged gasoline direct injection engine. Effects of compression ratio, exhaust gas recirculation (EGR), valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio, from 9.6 to 12, can improve fuel economy at relative low load (below 12 bar BMEP), but has a negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is reduced at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio.

Reducing the pumping loss, and thus, the fuel consumption of gasoline engine at part load, a two-stage intake valve lift system was implanted into a PFI engine. A corresponding engine model was set up with GT-power as well, which can simulate the effect of two-stage intake valve lift and different EGR rates on fuel economy performance and on combustion condition of a gasoline engine. Based on simulation results, the valve lift control strategy and EGR control strategy was studied in this paper. Results showed that at low engine speed, when SMALL LIFT was used, the tumble flow and the combustion process in cylinder was improved and burn time duration became shorter, resulting in higher indicated efficiency and lower fuel consumption than by LARGE LIFT. With the introduction of the exhaust gas recirculation (EGR), lower fuel consumption was acquired.

The performances of heavy-duty natural gas engines have been limited by combustion temperature and NOx emissions for a long time. Recently, water injection technology has been widely considered as a technical solution in reducing fuel consumption and emissions simultaneously in both gasoline and diesel engines. This paper focuses on the impacts of intake manifold water injection on characteristics of combustion and emissions in a natural gas heavy-duty engine through numerical methods. A computational model was setup and validated with experimental data of pressure traces in a CFD software coupled with detailed chemical kinetics. The simulation was mainly carried out in low-speed and full-load conditions, and knock level was also measured and calculated by maximum amplitude of pressure oscillations (MAPO).

Gasoline direct injection (GDI) technology is admitted to be one of the most effective measures to improve the fuel economy for the spark ignition (SI) engines. Homogeneous Charge Compression Ignition (HCCI) combustion has advantages of low fuel consumption and ultra low NOx emissions. But the difficulty in the autoignition control and the narrow operation region inhibit the practical application of this technology. A hybrid combustion mode which combines SI mode and HCCI mode in separated working regions was regarded as a promising technology for HCCI engines. In addition, monitoring and providing feedback to the in-cylinder combustion characteristics is generally considered to be an effective method to improve and to optimize the combustion process. A lot of combustion information is included in the ion current generated by the in-cylinder combustion, and hence the ion current detection technique is considered to be a potential combustion feedback method.

As the commercial vehicle increases staggeringly in China, environmental pollution and excessively fuel consumption can't be neglected anymore. Vehicle thermal management has been adopted by many vehicle manufactures as an ideal alternative to reduce fuel consumption and exhaust emission by its cost-efficient and effective merit. In addition, the components in heavy duty commercial vehicle engine hood may suffer overheat harm. Hence investigating the thermal characteristics in engine hood can be an effective way to identify and dismiss the potential overheat harm. In terms of this, the paper has adopted CFD simulation method to obtain the comprehensive thermal flow field characteristics of engine hood in a heavy commercial vehicle. Then by analyzing the thermal flow field in engine hood, concerning optimization strategies were put forward to improve the thermal environment.