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The control of fuel ignition timing and suppression of rapid combustion in a premixed charge compression ignition (PCCI) engine was attempted with direct in-cylinder injection of water as a reaction suppressor. The water injection significantly reduced the heat release at low temperature oxidation, which suppressed the increase in charge temperature after the low temperature oxidation and the rapid combustion caused by the high temperature oxidation. ...The possible engine operating range with ultra low NOx and smokeless combustion was extended to a higher load range with the water injection. Rapid combustion was suppressed by reductions in the maximum in-cylinder gas temperature due to water injection while the combustion efficiency suffered. ...Rapid combustion was suppressed by reductions in the maximum in-cylinder gas temperature due to water injection while the combustion efficiency suffered. Therefore, the maximum charge temperature needs to be controlled within an extremely limited range to maintain a satisfactory compromise between mild combustion and high combustion efficiency.

Experimental results obtained through modification of a CFR test engine confirm the predicted effectiveness of water injection on nitric oxide control. For a water injection rate 1-1/4 times the engine fuel consumption rate, nitric oxide reductions of over 90%were achieved. ...Theoretical analysis based on chemical equilibrium calculations indicates that the reduction of combustion temperature due to water injection at rates comparable to the engine fuel consumption rate is sufficient to yield significant reductions in nitric oxide emissions. ...Parallel theoretical and experimental studies of the influence of inlet manifold water injection on nitric oxide emission from spark ignition engines have been performed. Theoretical analysis based on chemical equilibrium calculations indicates that the reduction of combustion temperature due to water injection at rates comparable to the engine fuel consumption rate is sufficient to yield significant reductions in nitric oxide emissions.

The influence of water injection on the combustion process and raw emissions was analyzed experimentally on a single-cylinder research engine with direct and indirect water injection. Even though water injection initially slows down the combustion process, both injection concepts allow a clear shift in the knock limit and a reduction in the exhaust gas temperature. ...A promising technology to solve these conflicting objectives is the injection of water. Both the indirect and the direct water injection achieve a significant reduction in the load temperature. ...Experimental investigations on particle size distribution in connection with different water injection concepts are not yet known. Water injection strategies are worked out with a variation of the injection parameters.

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.

In this paper a combustion concept is presented that may be well suited to these applications. The novel combustion concept operates in two distinct operation modes: lean operation at light engine loads and stoichiometric operation at intermediate and high engine loads. ...The two-mode diesel combustion concept was implemented on a 6.8L medium duty diesel engine and several iterations of the combustion system were evaluated for smoke response and combustion efficiency. The engine was then evaluated over the Non Road Transient Cycle (NRTC) to evaluate performance, emissions and fuel consumption. ...Results show that this novel combustion concept can meet the Tier 4 final emissions regulations without the use of selective catalytic reduction (SCR).

Water injection effects on combustion phenomena have been investigated for several years, from both a theoretical and experimental viewpoints due to the collaboration of AGIP PETROLI and ISAB ERG Refinery. ...In this paper the effects of water injection on diesel combustion are investigated and reported. Using single cylinder CFR engine Cetane (AGIP PRIOLO Engine 11361/1) cetane number (C.N.) and NOx emissions have been measured. ...NOx emissions reduction confirm the effectiveness of water injection in reducing the engine environmental impact. Results have shown that water injection really represent a new way to control NOx formation in Diesel Engine and to reduce compression work.

A 3D computational fluid dynamics model is applied to simulate the in-cylinder mixing and combustion for this engine both with and without water injection. Different water injection timings are investigated and it is found that the injection timing greatly effects the mass of water which enters the combustion chamber, both in liquid and vapor form. ...Comparison have been given between the original engine and the water injection one and the results show that the water injection can reduce the cylinder temperature both in the compressing and combustion strokes. ...Port water injection is considered as a promising strategy to further improve the combustion performance of internal combustion engines for its benefit in knock resistance by reducing the cylinder temperature.

The numerical analysis has been also used in order to simulate the direct water injection in the same engine. A 6-hole high-pressure water injector has been implemented within the 3-D model of the engine combustion chamber. ...Water injection represents a promising tool to improve performance of spark-ignition engines. It allows reducing in-cylinder temperature, preventing knock risks. ...Optimizing the spark advance, water injection allows obtaining an increase of both efficiency and power output, particularly at medium and high loads.

The potential benefits of water injection on performance and emissions were investigated on a downsized PFI twin-cylinder turbocharged spark ignition engine. ...For each test case the effect of the injected water quantity on combustion and exhaust emissions was investigated by sweeping from 10%w to 30%w the water to gasoline ratio. ...For each test case the effect of the injected water quantity on combustion and exhaust emissions was investigated by sweeping from 10%w to 30%w the water to gasoline ratio. The water was injected at the same timing as the gasoline by a low pressure injection system external controlled.

This configuration results in minimal airplane payload weight penalties because it uses less than half the water of the compressor water misting method. The combustor water injection method reduces the turbine inlet temperature just enough during takeoff that it would greatly improve engine hot section life which would reduce engine maintenance costs. ...The two current preferred methods of water injection are: (1) direct injection into the combustor, and (2) misting of the conditioned water before the engine's compressor. ...In order to reduce these temperatures and improve engine life, both water injection systems were evaluated for use all the way to top of climb. Although the water misting system showed better engine performance results, the best solution may be the combustor injection method when used for takeoff only.

The combustion has been modelled with an ECFM model and an 88-species and 349-reactions chemical kinetics mechanism, in order to evaluate the pollutant emissions and their potential reduction due to supercritical water injection. The water injector has been modelled as a convergent-divergent nozzle which is located along the cylinder axis. ...Supercritical water injection for ICEs may be a valid option to recover engine wall heat transfer and energy from exhaust gases, with benefits in terms of efficiency and performances. ...A preliminary study of this energy recovery approach has already been performed in an authors’ previous work, by employing a port fuel injection (PFI) internal combustion engine quasi-dimensional model, which has been validated against experimental data, returning satisfactory results in terms of overall efficiency gain.

Traditional and split-injection strategies for the introduction of diesel fuel into the pre-chamber were evaluated by varying spray-related parameters including total injected mass, injection pressure, start of injection(s), and injection duration(s). The main metrics used to evaluate the engine’s operation include (1) pre-chamber, main chamber, and overall combustion efficiencies and (2) closed-cycle average load performance determined by a relative indicated mean effective pressure metric. ...The main metrics used to evaluate the engine’s operation include (1) pre-chamber, main chamber, and overall combustion efficiencies and (2) closed-cycle average load performance determined by a relative indicated mean effective pressure metric. ...Pre-chamber and main chamber maximum pressures were kept below 150 bar and injection pressures were limited at 1000 bar. As a result of this study, the best-performing cases demonstrated an overall combustion efficiency (ηc) that surpassed 90%, in both mid-load and high-load operating conditions.

Several water injection strategies, including direct water injection, indirect water injection, injection timing, and pressure variations, are considered for a better understanding of the benefits brought by the combination of an eFuel with water injection. ...This work is part of the FVV project number 1367, “Water Injection in Spark-Ignition Engines II”, which investigates the coexistence of two different engine technologies that heads towards the same direction of sustainability of the internal combustion engine: water injection and eFuels. The goal is to assess the advantages that the adoption of an eFuel in combination with water injection strategies can bring, with respect to the same strategies applied in combination with commercial gasoline. ...One common trend is to develop smaller engines able to operate in stoichiometric conditions across the whole engine map for better efficiency, lower fuel consumption, and optimal conversion rate of the three-way catalyst (TWC). Water injection is one promising technique, as it significantly reduces the engine knock tendency and avoids fuel enrichment for exhaust temperature mitigation at high power operation.

This paper examines the effects of combining an advanced direct injection strategy with water injection for efficiency benefits and emissions reduction of a hydrogen fuelled DI spark ignition (SI) engine. ...Results from experimental investigations at various levels of water injection on engine efficiency, combustion duration and stability as well as NOx emissions are discussed. ...The results show that water injection into the intake manifold results in a decrease in the NOx emissions up to nearly 55% at a marginal loss in efficiency.

In-cylinder pressure data, acquired by pressure sensors flush-mounted within the combustion chamber of both cylinders, allowed estimating the main combustion parameters such as the rate of heat release and the combustion phasing. The effect of water injection on turbine inlet temperature and combustion efficiency, estimated from the exhaust gaseous emissions (HC, CO, CO2), are also presented. ...The results coming from such analysis are discussed to determine the capability of water injection to reduce combustion noise level and improve sound quality index....A technique that has the potential to overcome these restrictions is based on the injection of a precise amount of water within the mixture charge that can allow to achieve important benefits on knock mitigation, engine efficiency, gaseous and noise emissions.

In this work we are discussing one of the method to reduce this emission by introducing water into the combustion chamber through the inlet manifold during suction stroke. The experimental part of the work involves the fabrication of a separate water injection system consisting of pump and an injector being driven by the engine itself. ...The experimental part of the work involves the fabrication of a separate water injection system consisting of pump and an injector being driven by the engine itself. Water is introduced in the inlet manifold and different performance tests like heat balance, load test and emission measurements are conducted on a Kirloskar Engine. ...In today's modern world the internal combustion engine has a predominant role in stationary low power generation and a virtual monopoly in mobile application.

As an alternative, the anti-knock characteristics of lower AKI fuels can be improved with water injection. In this sense, the water injection increases the ‘effective AKI’ of the fuel. The injected water absorbs heat, which lowers the in-cylinder temperatures and mitigates knock, which permits advancing the knock limited CA50 (KLCA50) and reducing fuel consumption for a given speed-load condition. ...This was accomplished by comparing the anti-knock performance of a high AKI reference fuel to lower AKI fuels supplemented with water injection. Tests were conducted at varying speeds and loads to investigate trends in the relationship between effective AKI per unit water injected. ...The results showed that engine speed does not have a profound effect on the required water-fuel ratio, but as the load is increased, less water is required to increase the effective AKI by a specific amount. The effect of water injection on COV of IMEP was also observed.

A new direct injection system, based on the hydraulic phenomenon commonly known as “water hammer” has been recently proposed by the authors to be used for small two-stroke engines. ...Recent research on internal combustion spark ignited engines has focused more and more on charge control by means of direct injection. ...Recent research on internal combustion spark ignited engines has focused more and more on charge control by means of direct injection. Nevertheless most of the systems proposed so far do not seem to be suitable for small engines as they are high-cost.

To help solve these problems, direct (in-cylinder) water injection has been suggested to lower the local temperatures that seem to cause knock in HCCI. ...To help solve these problems, direct (in-cylinder) water injection has been suggested to lower the local temperatures that seem to cause knock in HCCI. Water injection was adapted in an HCCI engine fueled with DME and Propane. Results showed that the indicated thermal efficiency was improved by about 2% (λ = 3.0, NA), and the operation range was expanded from 460kPa to 700kPa (NA) maintaining a low NOx level. ...HCCI (Homogeneous Charge Compression Ignition) combustion results in very low NOx emissions, however, it is not without problems. One of them is that the heavy load operation range is limited by knock, due to an exceptionally high heat release rate.

In this exhaustive study, first a comparative investigation is conducted between diesel and 10% emulsion; and in the consequent phases, performance and emission characteristics of 10% water diesel emulsion is evaluated at various injection angles on a single cylinder, water cooled diesel engine. ...Some of the fuel, which includes biodiesel, alcohol-diesel emulsions and diesel water emulsions etc. Among which the diesel water emulsion (DWE) is found to be most suitable fuel due to reduction in particulate matter and NOx emission, besides that it also improves the brake thermal efficiency. ...In the comparative study for different injection angles, it is found that on advancing the injection angle the peak pressure is shifted towards TDC and because of that, torque is increased slightly.