Effects of Super Heating of Heavy Fuels on Combustion and Performance in DI Diesel Engines

1986 ◽  
Author(s):  
Tadashi Murayama ◽  
Young-taig Oh ◽  
Akihiro Kido ◽  
Takemi Chikahisa ◽  
Noboru Miyamoto ◽  
...  
Author(s):  
Zhentao Liu ◽  
Jinlong Liu

Market globalization necessitates the development of heavy duty diesel engines that can operate at altitudes up to 5000 m without significant performance deterioration. But the current scenario is that existing studies on high altitude effects are still not sufficient or detailed enough to take effective measures. This study applied a single cylinder direct injection diesel engine with simulated boosting pressure to investigate the performance degradation at high altitude, with the aim of adding more knowledge to the literature. Such a research engine was conducted at constant speed and injection strategy but different ambient conditions from sea level to 5000 m in altitude. The results indicated the effects of altitude on engine combustion and performance can be summarized as two aspects. First comes the extended ignition delay at high altitude, which would raise the rate of pressure rise to a point that can exceed the maximum allowable limit and therefore shorten the engine lifespan. The other disadvantage of high-altitude operation is the reduced excess air ratio and gas density inside cylinder. Worsened spray formation and mixture preparation, together with insufficient and late oxidation, would result in reduced engine efficiency, increased emissions, and power loss. The combustion and performance deteriorations were noticeable when the engine was operated above 4000 m in altitude. All these findings support the need for further fundamental investigations of in-cylinder activities of diesel engines working at plateau regions.


1987 ◽  
Author(s):  
Y. Itoh ◽  
M. Kawamoto ◽  
H. Fujiwara ◽  
M. Kawakami ◽  
T. Nagai

Author(s):  
Wenming Yang ◽  
Hui An ◽  
Jing Li ◽  
Amin Maghbouli ◽  
Kian Jon Chua

Transportation is one of the major contributors to the world’s energy consumption and greenhouse gases emissions. The need for increased efficiency has placed diesel engine in the spotlight due to its superior thermal efficiency and fuel economy over gasoline engine. However, diesel engines also face the major disadvantage of increased NOx emissions. To address this issue, three types of emulsion fuels with different water concentrations (5%, 10% and 15% mass water) are produced and tested. Novel organic materials (glycerin and ployethoxy-ester) are added in the fuel to provide extra oxygen for improving combustion. NP-15 is added as surfactant which can help to reduce the oil and water surface tension, activates their surface, and maximizes their superficial contact areas, thereby forming a continuous and finely dispersed droplets phase. The stability of the emulsion fuels is tested under various environmental temperature for one year, and no significant separation is observed. It is better than normal emulsion fuel which can only maintain the state for up to three months. The combustion process and performance of the emulsion fuels are tested in a four-stroke, four cylinder diesel engine. The results indicate that the water droplets enclosed in the emulsion fuel explode at high temperature environment and help to break up the big oil droplets into smaller ones, thereby significantly increase the surface area of the oil droplets and enhance the heat transfer from hot gas to the fuel. As a result, the fuel evaporation is improved and the combustion process is accelerated, leading to an improved brake thermal efficiency (up to 14.2%). Meanwhile, the presence of the water causes the peak temperature of the flame to drop, thereby significantly bringing down the NOx emissions by more than 30%.


Author(s):  
G D Zhang ◽  
H Liu ◽  
X X Xia ◽  
W G Zhang ◽  
J H Fang

The physical and chemical properties of some oxygenated compounds are discussed, including dimethoxymethane (methylal, or DMM), dimethyl carbonate (DMC), and ethyl acetate. In particular, DMC may be a promising additive for diesel fuel owing to its high oxygen content, no carbon-carbon atomic bonds, suitable boiling point, and solubility in diesel fuel. The aim of this research was to study the combustion characteristics and performance of diesel engines operating on diesel fuel mixed with DMC. The experimental results have shown that particulate matter (PM) emissions can be reduced using the DMC oxygenated compound. The combustion analysis indicated that the ignition delay of the engine fuelled with DMC-diesel blended fuel is longer, but combustion duration is much shorter, and the thermal efficiency is increased compared with that of a base diesel engine. Further, if injection is also delayed, NOx emissions can be reduced while PM emissions are still reduced significantly. The experimental study found that diesel engines fuelled with DMC additive had improved combustion and emission performances.


Purpose. Creation of a scientific and practical basis for the development on the basis of mini and micro tunnels of universal low-cost systems for the environmental certification of transport diesel engines in terms of the mass emission of particulate matter with exhaust gases. Methods. Analysis and synthesis of information when studying the systems of ecological certification of diesel engines, physical and mathematical modeling, experimental research of working processes, technical characteristics and efficiency indicators of tunnels. Results. The technical characteristics of mini and micro-tunnels as control systems for mass emissions of diesel particulate matter are considered. The concept of the creation of universal mini- and microtunnels is proposed based on the principles of increasing their compactness, dynamism, management efficiency and accuracy. Conclusions. The results of theoretical and experimental researches and developments on increasing the universality of mini- and microtunnels are presented: mathematical models of work processes, resulting errors and performance indicators of tunnel; new isokinetic and compensation methods for controlling exhaust gas samples; prototypes of a minitunnule with an isokinetic sampler MT-1, microtunnels MKT-1 and MKT-2; test benches for studies of thermal processes in tunnels, isokinetic and compensation sampling regimes; results experimental development of certification procedures for measuring emissions of particulate matter from automotive, tractor and diesel locomotives.


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