다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

A review of hydrogen as a compression ignition engine fuel

http://www.mikalsen.eu/papers/hydrogenHCCI.pdf

An investigation of hydrogen-fuelled HCCI engine performance and operation

A paradigm shift towards the utilization of carbon-neutral and low emission fuels is necessary in the internal combustion engine industry to fulfil the carbon emission goals and future legislation requirements in many countries. Hydrogen as an energy carrier and main fuel is a promising option due to its carbon-free content, wide flammability limits and fast flame speeds. For spark-ignited internal combustion engines, utilizing hydrogen direct injection has been proven to achieve high engine power output and efficiency with low emissions. This review provides an overview of the current development and understanding of hydrogen use in internal combustion engines that are usually spark ignited, under various engine operation modes and strategies. This paper then proceeds to outline the gaps in current knowledge, along with better potential strategies and technologies that could be adopted for hydrogen direct injection in the context of compression-ignition engine applications—topics that have not yet been extensively explored to date with hydrogen but have shown advantages with compressed natural gas.

A Review of Hydrogen Direct Injection for Internal Combustion Engines: Towards Carbon-Free Combustion

A review of controlling strategies of the ignition timing and combustion phase in homogeneous charge compression ignition (HCCI) engine

Hydrogen has been proposed as a possible fuel for automotive applications This paper reports an experimental investigation of hydrogen as HCCI engine fuel The aim of the experimental study is to investigate the possibility to run an HCCI engine on an extremely fast burning fuel such as hydrogen as well as to study the efficiency, the combustion phasing and the formation of emissions The experiments were conducted on a single-cylinder research engine with a displacement volume of 16 litres and pancake combustion chamber geometry Variation of lambda, engine speed, compression ratio and intake temperature were parts of the experimental setting The engine was operated in Homogenous Charge Compression Ignition (HCCI) mode and as comparison also in Spark Ignition (Sl) mode Hydrogen was found to be a possible fuel for an HCCI engine The heat release rate was extremely high and the interval of possible start of combustion crank angles was found to be narrow The high rate of heat release limited the operating range to lean (λ>3) conditions On the other hand operation on extremely lean mixtures (X=6) was found possible The possible operating range was investigated when intake gas temperature was used for control and also this control interval was found to be narrow, especially when richer cases were run The maximum load in HCCI mode was an IMEPn of 35 bar which is about half of the load possible in Sl mode and about half the maximum load in HCCI mode with other fuels For the loads where HCCI operation could be conducted indicated thermal efficiency for HCCI was superior to that of SI NOx emissions were, as expected, found to decrease when lambda was increased and the levels were very low in HCCI mode High levels of hydrogen were found in the exhaust with HCCI When the engine was operated on low lambdas (ie λ=3) emissions of carbon monoxide and hydrocarbons were detected, probably originating from evaporated and partially oxidized lubrication oil

Hydrogen as Homogeneous Charge Compression Ignition Engine Fuel

Several studies have shown that NO has a strong influence on engine knock. This paper reports an experimental study that addresses the connection between SI engine knock and the level of nitric oxide, NO, in the intake manifold gas under various conditions of engine operation. Some theories explain the second ion-current peak as thermal ionisation of NO. Both temperature and NO concentration is of importance. By advancing the ignition angle the NO concentration can be increased, but the temperature is also increased. Addition of NO in the inlet manifold increases the NO concentration but has less effect on the temperature. SI engine experiments were conducted over a number of different ignition timings, air/fuel ratios, engine speeds and intake manifold pressures. The NO level in the intake manifold was altered from 100 to 1600 ppm, increasing the amount by doubling. The study confirms that there is an increasing tendency of early knock when the NO amount increases. A slight increase in the second ion-current peak could be seen with addition of NO in the inlet manifold, especially with early ignition timing. This increase in peak amplitude may be a result of heavy knock, due to the addition of NO. Advancing the ignition angle 2 crank angle degrees has a stronger influence on the second ion-current peak than addition of 1600 ppm NO in the inlet manifold.

Measurement of Knock and Ion Current in a Spark Ignition Engine with and without NO Addition to the Intake Air

The present invention pertains to a method for the regulation of a temperature in an exhaust stream in a motor vehicle through control of its driveline, the motor vehicle of which comprises: a driveline comprising a combustion engine which may be connected to an automatic gearbox or a manual gearbox via a clutch device, where the said automatic gearbox or the said manual gearbox has several discrete gears, and an exhaust system arranged for the removal of an exhaust stream from the said combustion engine; where the said method comprises the steps: - obtaining one or several first parameters P 1, where at least one of the one or several first parameters P 1 is a first temperature difference between a first temperature T 1 in the said exhaust system and a reference temperature T Ref ; and control of the said automatic gearbox or the said manual gearbox, and thus an operating point in the said combustion engine through downshift to a lower gear, and thus an increase of an engine speed and a reduction of a load of the said combustion engine, if a value for the said one or several first parameters P 1 exceeds a first threshold, and an upshift to a higher gear, and thus a reduction of an engine speed and an increase of a load of the said combustion engine, if a value for the said one or several first parameters P 1 is below a second threshold value. Further, the invention pertains to a computer program, a computer program product, a system and a motor vehicle comprising such a system.

Regulation of a temperature in an exhaust aftertreatment system

Global warming and climate change have led to a greater interest in the implementation of biofuels in internal combustion engines. In spark ignited engines, biofuels have been shown to improve effi ...

Future Fuels for DISI Engines: A Review on Oxygenated, Liquid Biofuels

Factors influencing the effect of pilot-injection on main-injection combustion were investigated using heat release analysis in a heavy-duty diesel engine fuelled with standard diesel fuel, and included the effect of those factors on engine performance and emissions.Combinations of pilot injection parameters i.e. pilot start of injection, pilot mass, pilot-main injection separation, and rail pressure were studied for various operating conditions and combustion phases.It was concluded that the effect of pilot-injection combustion on main injection can be studied based on the phase of pilot combustion at the start of main injection. Four cases were identified: a) main injection during the mixing phase of pilot injection; b) main injection during the premixed phase of pilot combustion; c) main injection during the diffusive phase of pilot combustion and d) main injection after pilot combustion was completed.The effect of pilot injection was illustrated by the conceptual model of interaction modes. This approach has the advantage that the effect of each mode on the main injection is independent of the pilot injection parameters. For combustion control stability and convergence reasons, it is important to consider the transition between the four different interaction modes in regard to variances in the chamber conditions, pilot injected mass and pilot injection combustion. (Less)

Ola Stenlåås

Papers

Hydrogen as Homogeneous Charge Compression Ignition Engine Fuel

Measurement of Knock and Ion Current in a Spark Ignition Engine with and without NO Addition to the Intake Air

Regulation of a temperature in an exhaust aftertreatment system

Future Fuels for DISI Engines: A Review on Oxygenated, Liquid Biofuels

Influence of Small Pilot on Main Injection in a Heavy-Duty Diesel Engine