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In this paper, a low-speed pre-ignition (LSPI) diagnostic strategy is designed based on the ion current signal. Novel diagnostic and re-injection strategies are proposed to suppress super-knock induced by pre-ignition within the detected combustion cycle. A parallel controller system that integrates a regular engine control unit (ECU) and CompactRIO (cRIO) from National Instruments (NI) is employed. Based on this system, the diagnostic and suppression strategy can be implemented without any adaptions to the regular ECU. Experiments are conducted on a 1.5-liter four-cylinder, turbocharged, direct-injected gasoline engine. The experimental results show two kinds of pre-ignition, one occurs spontaneously, and the other is induced by carbon deposits. Carbon deposits on the spark plug can strongly interfere with the ion current signal. By applying the ion current signal, approximately 14.3% of spontaneous and 90% of carbon induced pre-ignition cycles can be detected.

Based on the working model of a diesel engine, the influence of 2 Miller cycle strategies-Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC) on the combustion and emissions of diesel engine was analyzed. Then the working condition of each Miller cycle strategies on the engine under the rated speed was optimized through the adjust of the valve timing, boost pressure and the injection timing. The research found that both delaying and advancing the closure timing of the intake valve can decrease the pressure and temperature during compression stroke, prolonging the ignition delay. However, due to the decrease of the working media inside the cylinder, the average in-cylinder temperature and soot emissions will increase, which can be alleviated by raising the boost pressure and the resulting compensation of the intake loss.

In recent years, particulate matters (PM) emissions from gasoline direct injection (GDI) engines have been gradually paid attention to, and the hydrous ethanol has a high oxygen content and a fast burning rate, which can effectively improve the combustion environment. In addition, Exhaust gas recirculation (EGR) can effectively reduce engine NOx emissions, and combining EGR technology with GDI engines is becoming a new research direction. In this study, the effects of hydrous ethanol gasoline blends on the combustion and emission characteristics of GDI engines are analyzed through bench test. The results show that the increase of the proportion of hydrous ethanol can accelerate the burning rate, shorten the combustion duration by 7°crank angle (CA), advance the peak moment of in-cylinder pressure and rate of heat release (RoHR) and improve the combustion efficiency. The hydrous ethanol gasoline blends can effectively improve the gaseous and PM emissions of the GDI engine.

To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated.

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.

In this paper, characteristics of gas emission and particle size distribution are investigated in a common rail diesel engine fueled with biodiesel blends. Gas emission and particle size distribution are measured by AVL FTIR - SESAM and SMPS respectively. The results show that although biodiesel blends would result in higher NOx emissions, characteristics of NOx emissions were also dependent on the engine load for waste cooking oil methyl ester. Higher blend concentration results in higher NO2 emission after two diesel oxidation catalyst s (DOC). A higher blend concentration leads to lower CO and SO2 emissions. No significant difference of Alkene emission is found among biodiesel blends. The particle size distributions of diesel exhaust aerosol consist of a nucleation mode (NM) with a peak below 50N• m and an accumulation mode with a peak above 50N • m. B100 will result in lower particulates with the absence of NM.

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.

Recently Hybrid Electric Buses (HEBs) have been widely used in China for energy saving and emission reduction. In order to study the real road emission performance of HEBs, the emission tests of an in-use diesel-electric hybrid bus (DHEB) are evaluated both on chassis dynamometer over China City Bus Cycles (CCBC) and on-road using Portable Emissions Measurement Systems (PEMS). The DHEB is powered by electric motor alone at speed of 0~20km/h. When the speed exceeds 20km/h, engine gets engaged rapidly and then works corporately with the electric motor to drive the bus. For chassis dynamometer test over CCBC, emissions of NOx, particulate number, particulate mass, and THC of the DHEB are 7.68g/km, 5.88E+11#/km, 0.412mg/km, and 0.062g/km, respectively. They have all decreased greatly compared to those of the diesel bus. But the CO emission which is 3.48g/km has increased significantly. Then the Real Driving Emissions (RDE) of the DHEB are compared with the dynamometer test results.

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.

Due to much higher pressure and pressure rising rate, knocking is always of potential hazards causing damages in the engine and high NOX emissions. Therefore, the researchers have focused on knocking diagnosis and control for many years. However, there is still lack of fast response sensor detecting in-cycle knocking. Until now, the feedback control based on knocking sensor normally adjusts the injection and ignition parameters of the following cycles after knocking appears. Thus in-cycle knocking feedback control which requires a predictive combustion signal is still hard to see. Ion current signal is feasible for real-time in-cylinder combustion detection, and can be employed for misfiring and knocking detection. Based on incylinder pressure and ion current signals, the in-cycle knocking feedback control is investigated in this research. The 2nd-order differential of in-cylinder pressure, which means the response time of pressure rising rate dPR, is employed for knocking prediction.

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.

Due to the oil crisis and the requirements of energy saving and emission reduction, the research of alternative energy sources for sustainable development has made good progress. Methanol has proven to be a very suitable alternative clean fuel. Compared with gasoline, methanol has a wide range of source and the higher oxygen content and octane number and combustion efficiency, which are beneficial for the engine performance. The effect of different proportions of methanol-gasoline mixed fuel on the performance of SI engine was studied experimentally (lower proportion and higher proportion). It was found that the engine power performance, fuel economy and exhaust emissions were related to the methanol ratio under different operating conditions. In order to adapt to different operating conditions to improve the performance of methanol-gasoline engine, an on-board flexible fuel mixed system was proposed.

In vehicle application, most of time gasoline engines are part load operated, especially in city traffic, part load operation covers most common operation situations, however part load performances deteriorate due to pumping losses and low thermal efficiency. Many different technologies have been applied to improve part load performances. One of them is to adopt over-expanded (Atkinson/Miller) cycle, which uses late/early intake valve closing (LIVC/EIVC) to reduce pumping losses in part load operation. But over-expanded cycle has an intrinsic drawback in that combustion performance deteriorates due to the decline in the effective compression ratio (CR). Combining with high geometry CR may be an ideal solution, however there is a trade-off between maintaining a high CR for good part load fuel consumption and maintaining optimal combustion phasing at higher load.

Regulated gaseous and particulate matter (PM) emissions in the exhaust from a heavy duty diesel engine with biodiesel fuel were studied, and the emission characteristics of PM and polycyclic aromatic hydrocarbons (PAHs) emissions in PM were highlighted. In the experiment, pure diesel fuel and B10 (a blend of diesel and biodiesel fuels with the volume ratio of 9 to 1) fuel were chosen. The study shows that, compared to the pure diesel, the emissions of PM, soluble organic fractions (SOF) and PAHs from the heavy duty diesel engine decrease when the engine burns B10 fuel, and the nitrogen oxides (NOx) emission slightly increases, while the unburned hydrocarbon (HC) and carbon monoxide (CO) emissions also decline. Among the detected 12 kinds of PAHs, emission concentrations of 10 kinds of PAHs from the engine with B10 descend. Especially Benzo(a)pyrene equivalent toxicity (BEQ) analysis results show that the BEQ of B10 fuel decreases by 15.2% compared to pure diesel.

The diesel engine is the core in the field of engineering machine power plants. While both at home and abroad for the cold start of diesel engine, the transient emission characteristics below 0 °C and above 2000m is almost a blank. Therefore, aimed at high altitude and low-temperature environment emission characteristics of cold start, this article has carried on the systematic analysis and research. In this paper, a simulation test system for the cold start of the diesel engine at low temperature at high altitude is established. The cold start experiments of a heavy diesel engine at different ambient temperatures (10°C, 0°C, -10°C and -20°C) and different altitudes (0m, 3000m, and 4000m) is carried out. In this paper, the gas emission of the diesel engine during the speed-up period of cold start is studied.

It has been revealed by researches that lubricant properties have a great effect on the low-speed pre-ignition (LSPI) frequency in downsizing turbocharged direct-injection engines which are developed for better fuel economy. Droplets of lubricant or lubricant-gasoline mixture are considered to be the potential pre-ignition sources. Those droplets fly into the combustion chamber and ignite the gasoline-air mixture. To study lubricant droplets fundamentally, a novel set of droplet auto-ignition system is designed based on a Dibble Burner for this experiment. Influences of metallic additive contents, viscosities, lubricant diluted with gasoline and waste lubricant on the ignition delay of droplets are investigated by testing 12 groups of lubricants or lubricant-gasoline mixture. The equivalent diameter of each droplet generated by micro-syringes is around 2.1 mm. The co-flow temperature varies from 1123 K to 1223 K, and the experiments are carried out at atmospheric pressure.

Compared with ordinary gasoline, using ethanol gasoline blends as fuel of Internal Combustion Engine is beneficial for the performance of power, economy and emission of engine. However, the fuel ethanol blended in ethanol gasoline blends currently is usually anhydrous ethanol, which requires dewatering implementer in production process, and the cost is high. Therefore, the production cost can be significantly reduced by replacement of anhydrous ethanol with hydrous ethanol while exerting the advantage of ethanol gasoline blends. In this study, computation fluid dynamics (CFD) software CONVERGE is employed to establish a simulation model of an actual gasoline direct injection (GDI) engine, and investigate the effect of burning hydrous ethanol gasoline blends and different injection strategy on combustion process and emission, and the validity of the model was validated by experiments.

Emissions of diesel engine have been received much more attention since the Volkswagen Emission Scandal. The Euro VI emission standard has already included cold start emissions in the legislative emission driving cycles which is one of the hardest part of emission control. High altitude performance is also considered in the latest regulations which will be stricter in the future. Heating the coolant is one of the most common method to improve the cold start performance. But researches focus on the emission of a diesel engine in different coolant temperature at high altitude which up to 4500m have not been seen. The present research investigated the effect of coolant temperature on performance and exhaust emissions (gaseous and particulate emissions) during the cold start of a diesel engine. A plateau simulation system controlled the inlet and exhaust pressure to create altitude environments from 0m to 4500m, and the coolant temperature was controlled from 20°C to 60°C.

In this study, the real-world NOx and particle emissions of buses burning pure diesel fuel (D100), biodiesel fuel with 20% blend ratio (B20) and liquefied natural gas (LNG) were measured with portable emission measurement system (PEMS). The measurement conducted at 6 constant speed, which ranged from 10km/h to 60 km/h at 10km/h intervals, and a period of free driving condition. The relationship between vehicle specific power (VSP) and NOx/particle emissions of each bus were analyzed. The results show that the change rules of NOx, PN and PM emission factors with the increase of VSP were basically the same for the same bus, but for the bus using different fuel, the change rules may change. In VSP bin 0, the vehicles were mostly in idle condition and the emission factors of NOx, PN and PM of three buses were all in a relatively high level. In low VSP interval, which ranged from bin 0 to bin 4, the emissions of three buses first decreased and then increased with the growth of VSP.