Search Results

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. ...The results show that the quantity of injected water does not have a negative effect on water spray and film at an appropriate position, but an increase in the quantity of injected water leads to a negative effect on charging efficiency and a decrease in IMEP.

In this regard, water injection into the intake of a heavy-duty diesel engine to reduce peak combustion temperature and thereby reducing NOx is found to be a promising technology. ...Current work involves the use of 1-D thermodynamic simulation using AVL BOOST for modeling the engine performance with water injection. Mixing Controlled Combustion (MCC) model was used which can model the emissions. ...Further to this, the water injector module was integrated to inject decided quantity of water from the experiment to get optimum emission reduction. 3D CFD analysis using CONVERGE was carried out in-order to assess the water spray characteristics. A selection of water injector based on the required injection quantity was carried out and engine experiments were carried out based on the recommendations of the simulation results.

One way to minimize these is the usage of exhaust gas re-circulation (EGR), Miller cycle and water injection. The reduced knocking tendency allows the geometric compression ratio to be increased further, which leads to an additional efficiency advantage. ...One alternative to conventional diesel propulsion is the usage of stoichiometric natural gas combustion. Due to the lowered C/H ratio and the cost effective exhaust after treatment (EAT) in form of a three way catalyst (TWC), less CO2 is emitted and it is possible to comply even with most stringent NOX legislations. ...However, the stoichiometric combustion of natural gas has also disadvantages. In particular, the throttling and retarded 50 % mass fuel burned (MFB50) positions due to knocking lead to efficiency losses.

Additionally, a water injection system is integrated. All three technologies are investigated on their own and in combination. ...To reduce longer combustion durations caused by Miller valve timing and charge dilution, a piston bowl with extra high turbulence generation is designed. ...The results show, that high swirl motion and high turbulence can lead to a disadvantage in efficiency despite faster combustion durations due to higher wall heat losses. However, by using suitable combinations, it is possible to minimize throttle losses in low load operation and achieve optimum combustion locations (8°CA aFTDC) at full load operation with conventional compression ratios (ε=12).

Introducing water in a diesel engine has been known to decrease peak combustion temperatures and decrease NOx emissions. ...This however, has been limited to stationary and marine applications due to the requirement of a separate water supply tank in addition to the fuel tank, thereby a two-tank system. Combustion of hydrocarbon fuels produce between 1.35 (Diesel) and 2.55 times (Natural Gas) their mass in water. ...Combustion of hydrocarbon fuels produce between 1.35 (Diesel) and 2.55 times (Natural Gas) their mass in water. Techniques for extracting this water from the exhaust flow of an engine have been pursued by the United States department of defense (DOD) for quite some time, as they can potentially reduce the burden of supply of drinking water to front line troops in theater.

In this work, DME is applied in a direct injection compression ignition combustion application. A novel plunger-type injection system was used to pressurize DME to 415 bar. ...The ultra-low smoke characteristic of DME avoided the classical NOx-soot trade-off of diesel-fueled engines, allowing for combustion optimization through stronger exhaust gas dilution. DME showed improved combustion completeness likely owing to the self-containing oxygen and higher volatility minimizing the dependency on mixing with the in-cylinder surrounding compressed charge. ...Compression ignition internal combustion engines provide unmatched power density levels, making them suitable for numerous applications including heavy-duty freight trucks, marine shipping, and off-road construction vehicles.

Due to a catalytic reaction within the catalyst, NOx is converted nominally into Nitrogen and Water. Currently, the evaporative process is enhanced by aggressive mixer plates and long flow paths. ...In this study a novel biomimetic effervescent aqueous urea injector, its design inspired by the natural spray phenomenon of the Bombardier Beetle, is used to compare against a market-leading aqueous urea doser in comparable exhaust conditions with and without aggressive mixer plates being installed. ...In this study a novel biomimetic effervescent aqueous urea injector, its design inspired by the natural spray phenomenon of the Bombardier Beetle, is used to compare against a market-leading aqueous urea doser in comparable exhaust conditions with and without aggressive mixer plates being installed. The novel biomimetic effervescent injector operates by increasing the temperature of the Urea solution inside a constant volume chamber to its saturated vapour pressure.

For selection of an optimum COM preparation system, a series of tests on high intensity ultrasonic mixing devices is performed. A brief description of the system is presented. A coal-fuel oil-water mixture up to 25% coal concentration has been used as an alternative fuel in China standard Model 195-2 Single cylinder, 10 H.P. at rated 1800 RPM and Model 2135 Two cylinders, 40 H.P. at rated 1500 RPM diesel engines with very encouraging. Preliminary tests results are given in this paper.

Three different injection strategies (single injection, pilot-main injection, main-post injection) are experimentally investigated on a heavy duty compression ignition engine. ...The results show that all three injection strategies produced ultra-low soot emission, while less NOx emission was noticed for pilot-main injection because of less diffusion combustion mode. Pilot-main injection strategy decreases the maximum pressure rise rate effectively compared to single injection. ...Partially premixed combustion is a single fuel variant of this new combustion concepts applying a fuel with a low cetane number to achieve the necessary long ignition delay.

Dual-fuel reactivity controlled compression ignition (RCCI) engine experiments were conducted with port fuel injection of isooctane and direct injection of n-heptane. The experiments were conducted at a nominal load of 4.75 bar IMEPg, with low isooctane equivalence ratios. ...Two sets of experiments explored the effects of direct injection timing with single and double injections, and multi-dimensional CFD modeling was used to explore mixture preparation and timing effects. ...The findings were that if fuel-liner impingement is to be avoided, double injections provide a 40% reduction in CO and HC emissions, resulting in a 1% increase in thermal efficiency.

The present work discusses the effects of intake manifold water injection in a six-cylinder heavy duty natural gas (NG) engine through one-dimensional simulation. ...The intake manifold water injection mass was controlled through adjustment of intake water/gas (water/natural gas) ratio, a water/gas ratio swept from 0 to 4 was selected to investigate the effects of intake manifold water injection on engine performance and emissions characteristics. ...The intake manifold water injection mass was controlled through adjustment of intake water/gas (water/natural gas) ratio, a water/gas ratio swept from 0 to 4 was selected to investigate the effects of intake manifold water injection on engine performance and emissions characteristics. On the other hand, the enhancement potential of intake manifold water injection in heavy duty NG engine under lean and stoichiometric condition was also investigated by the alteration of air-fuel ratio.

In this work a single cylinder engine with 14:1 compression ratio (CR) was used to investigate spark ignited direct injection (SIDI) NG combustion using a novel spark injector-igniter. Two parameters were investigated, start of injection (SOI) timing and spark ignition (SPK) timing. ...Traditionally, port-fuel injection (PFI) or premixed NG spark-ignited (SI) combustion systems have been used for MD and HD engines with widespread use in the US and Europe; however, this technology exhibits poor cycle efficiency and is load limited due to knock phenomenon. ...An optimum range of SOI timing targeted in a partially stratified combustion (PSC) range (−130 to −50 degATDC) was shown. Significant improvement in combustion stability, phasing, and HC emissions contributed to reduced fuel consumption by up to 40% over premixed SI mode using the same injector.

An increase in the total number of particles was observed at 400°C and 1200 bar of fuel injection pressure with the higher AdBlue injection quantities compared to the dry-run SCR. At 400°C, a surge in nucleation occurs irrespective of the fuel injection pressures. ...At 400°C, a surge in nucleation occurs irrespective of the fuel injection pressures. An experiment was also made to isolate the water droplets effect on PN from nitrate formation. ...In this study, experiments were carried out on a heavy-duty Euro VI engine after-treatment system consisting of diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction (SCR) unit with AdBlue injection followed by ammonia slip catalyst. The present work focusses on the SCR unit with regard to total particle number with and without nucleation particles both.

The VOLKSWAGEN VANAGON SYNCRO is presented as a novel 4 WD. The visco coupling is the heart of the forward drive train. Main advantages are automatic performance distribution between the axles and self-locking at extreme revolution differences between front and rear. ...Electronic fuel injection and ignition are integrated into a unique Volkswagen system called DIGIFANTR. Vehicle performance data and fuel economy figures are given in comparison with 2 WD designs and previously available engine power train combinations.

Selected as an alternative diesel fuel based on consideration regarding the relationship between the fuel molecular structure and exhaust emission and criteria as alternative fuels, Dimethylacetal (DMA) was evaluated in both a direct injection (DI) diesel and a Direct Fuel Injection Impingement Diffusion Combustion Diesel (OSKA-D) engines.

In this experiment, the fuel adhering on the combustion chamber wall, and which influences the cold smoke, was measured on a special engine which can be stopped immediately after a single injection. It is found that 30-40% of the injected fuel remained on the combustion chamber wall after burning at low compression ratios and under low temperature conditions. ...In a direct injection (D.I) diesel engine with high efficiency, the blue and white smoke (cold smoke) exhaust at cold starting and warming-up are unsolved problems in the development of small D.I diesel engines. ...In this experiment, the fuel adhering on the combustion chamber wall, and which influences the cold smoke, was measured on a special engine which can be stopped immediately after a single injection.

The effects of a multi-hole nozzle with throttle construction (NTC) on combustion and emissions were investigated at high pressure fuel injection conditions. The throttle area was larger than the total injector hole area, therefore its fuel flow quantity was about the same as the standard nozzle under steady flow conditions. ...But the initial fuel injection rate was lower under unsteady flow conditions and smoke emissions were improved with the NTC.

This paper presents a numerical study of methanol combustion at different start-of-injection (SOI) in a direct injection compression ignition (DICI) engine supported by experimental studies. ...The aim is to investigate the combustion behavior of methanol with single and double injection at close to top-dead-center (TDC) conditions. ...In all injection conditions the combustion phasing is kept the same, i.e. with the 50-percentage heat release at the same crank angle (CA50) by adjusting the intake temperature.

Given the resistance to autoignition of ethanol, the engine is equipped with two injectors mounted in the same combustion chamber, allowing the simultaneous and independent actuation of the main injection of pure ethanol and a pilot injection of diesel as an ignition source. ...Given the resistance to autoignition of ethanol, the engine is equipped with two injectors mounted in the same combustion chamber, allowing the simultaneous and independent actuation of the main injection of pure ethanol and a pilot injection of diesel as an ignition source. The influence of the dual-fuel injection strategy on ethanol ignition, combustion characteristics, engine performance and NOx emissions is evaluated by varying the start of injection of both fuels and the ethanol-diesel ratio. ...Diesel substitution ratios above 80% on an energy basis are investigated, as the objective is to minimize diesel consumption while keeping stable and complete ethanol combustion. A minimum separation between ethanol and diesel injections is found to be necessary in order to limit the degree of premixing of ethanol at high load and avoid partial ethanol misfire causing combustion instability at low load, respectively.

In high pressure hydrogen injection hot surface ignition engines under nearly all engine operating conditions combustion pressure vibration is generated just after ignition. ...As a result of many experimental investigations the true nature for the cause of this interesting phenomenon was found and are listed: (1) This phenomenon probably originates from the extremely high local rate of burning of the hydrogen-air mixture. (2) Accompaning the stronger combustion pressure vibration was an increase in engine vibration and noise with increase in NOx emission and higher piston temperature. (3) Longer ignition delay resulted in a steeper pressure-time diagram which resalted in a stronger combustion pressure vibration. (4) The phenomenon had negligible effect on engine performance. (5) The phenomenon can be prevented by premixing a ceratain quantity of hydrogen gas into the intake air stream. ...As a result of many experimental investigations the true nature for the cause of this interesting phenomenon was found and are listed: (1) This phenomenon probably originates from the extremely high local rate of burning of the hydrogen-air mixture. (2) Accompaning the stronger combustion pressure vibration was an increase in engine vibration and noise with increase in NOx emission and higher piston temperature. (3) Longer ignition delay resulted in a steeper pressure-time diagram which resalted in a stronger combustion pressure vibration. (4) The phenomenon had negligible effect on engine performance. (5) The phenomenon can be prevented by premixing a ceratain quantity of hydrogen gas into the intake air stream.