INFRARED EXPERIMENTAL INVESTIGATIONS ON THE EFFECTS OF DIRECT WATER INJECTION IN AN OPTICAL ENGINE

2021 ◽  
pp. 1-15
Author(s):  
Amer Farhat ◽  
Taewon Kim ◽  
Ming-Chia Lai ◽  
Marcis Jansons ◽  
Xin Yu
Keyword(s):  
Thermal Stratification ◽  
Water Injection ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Maximum Temperature ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Residual Water ◽  
Effect Of Water ◽  
Direct Water Injection

Abstract The effects of water injection on combustion characteristics were investigated in an optically-accessible light-duty engine retrofitted with a side-mounted water injector. The main objective was to study the effect of water injection on autoignition and subsequent combustion process in compression ignition engines. Numerical zero-dimensional simulations were first performed to separate the thermal from the kinetic effects of water on the ignition delay and maximum temperature reached by a reacting mixture. Then, experimental investigations were performed at different intake temperatures and levels of thermal stratification achieved via direct water injection. Combustion analysis was performed on cylinder pressure data to study the effect of water injection on the overall combustion process. Infrared imaging was performed to provide insight to how water injection and the resulting water distributions affect thermal stratification, autoignition, and combustion characteristics. A new method in quantifying the water distributions is suggested. The results show that the overall level of stratification is sensitive to water injection timing and pressure, where increased water injection pressures and advanced injection timings result in more homogenous distributions. Moreover, water injection was found to affect the location of ignition kernels and the local presence of water suppressed ignition. The level of water stratification was also observed to affect the combustion process, where more homogenous distributions lost their ability to influence ignition locations. Finally, the infrared images showed high levels of residual water left over from prior water-injected cycles, suggesting that hardware configurations and injection strategies must be optimized to avoid wall wetting for stable engine operation.

Infrared Experimental Investigations on the Effects of Direct Water Injection in an Optical Engine

2020 ◽  
Author(s):  
Amer Farhat ◽  
Taewon Kim ◽  
Ming-Chia Lai ◽  
Marcis Jansons ◽  
Xin Yu
Keyword(s):  
Thermal Stratification ◽  
Water Injection ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Maximum Temperature ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Residual Water ◽  
Effect Of Water ◽  
Direct Water Injection

Abstract The effects of water injection on combustion characteristics were investigated in an optically-accessible light-duty engine retrofitted with a side-mounted water injector. The main objective was to study the effect of water injection on autoignition and subsequent combustion process in compression ignition engines. Numerical zero-dimensional simulations were first performed to separate the thermal from the kinetic effects of water on the ignition delay and maximum temperature reached by a reacting mixture. Then, experimental investigations were performed at different intake temperatures and levels of thermal stratification achieved via direct water injection. Combustion analysis was performed on cylinder pressure data to study the effect of water injection on the overall combustion process. Infrared imaging was performed to provide insight to how water injection and the resulting water distributions affect thermal stratification, autoignition, and combustion characteristics. A new method in quantifying the water distributions is suggested. The results show that the overall level of stratification is sensitive to water injection timing and pressure, where increased water injection pressures and advanced injection timings result in more homogenous distributions. Moreover, water injection was found to affect the location of ignition kernels and the local presence of water suppressed ignition. The level of water stratification was also observed to affect the combustion process, where more homogenous distributions lost their ability to influence ignition locations. Finally, the infrared images showed high levels of residual water left over from prior water-injected cycles, suggesting that hardware configurations and injection strategies must be optimized to avoid wall wetting for stable engine operation.

Optimization of Mixture Formation of Diesel Fuel in a Small CI Engine: The Effect of Water (H2O) Injection Into Intake Port

2017 ◽  
Author(s):  
Se Hun Min ◽  
Jeonghyun Park ◽  
Hyun Kyu Suh
Keyword(s):  
Water Injection ◽  
Injection Timing ◽  
Intake Port ◽  
Cylinder Pressure ◽  
Test Results ◽  
Analysis Model ◽  
Simultaneous Reduction ◽  
Effect Of Water ◽  
Rate Of Heat Release ◽  
Ci Engine

The objective of this study is to investigate the effect of water injection into intake port on the performance of small CI engine. The ECFM-3Z model was applied for the combustion analysis model, and the amount of injected water were varied 10%, 20% and 30% of injected fuel mass. The results of this work were compared in terms of cylinder pressure, rate of heat release (ROHR), and the ISNO and soot emissions. It was found that the cylinder pressure was decreased from 1.2% to 9.2% when the amount of injected water was increased from 10% to 30%. In the results, NO emission significantly decreased from about 24% to about 85% when the amount of injected water increased due to the specific heat and latent heat of water. Considering the test results, the best conditions for the simultaneous reduction of NO and soot is the BTDC 05deg of injection timing and 30% of water injection mass. It can be expected the best IMEP and ISFC characteristics.

Computational and Experimental Analysis of Direct CNG Injection and Mixture Formation in a Spark Ignition Research Engine

2010 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Francesco C. Pesce
Keyword(s):  
Numerical Model ◽  
Combustion Chamber ◽  
Cone Angle ◽  
Combustion Process ◽  
Laser Induced Fluorescence ◽  
Operating Conditions ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Mixture Formation

Direct injection (DI) of compressed natural gas (CNG) under high pressure conditions is a topic of great interest, owing to its potential for improving SI engine performance and fuel consumption. However, relevant technical difficulties have yet to be resolved in order to stabilize combustion process, especially for stratified engine operating conditions. The present paper is focused on experimental and numerical investigations of the jet formation and fuel-air mixing process in a research optical-access single-cylinder engine. The engine is based on the multi-cylinder engine under development within the European Community (EC) VII Framework Program (FP) InGAS Integrated Project, and features a centrally mounted poppet-valve injector on a pent-roof combustion chamber with a bowl in piston. Experimental investigations were made by means of the planar laser-induced fluorescence technique, and revealed a cycle-to-cycle jet shape variability. In particular, for specific cylinder pressure values at the start of injection, the jet can adhere to chamber walls for a relevant number of cycles, leading to an ‘umbrella-like’ shape. This can change the mixing capabilities of the combustion chamber and cause instabilities in the combustion process. The mentioned behaviour is strongly dependent not only on the injection and cylinder pressures, but also on important design parameters, such as needle cone angle and in-chamber injector protrusion. For this reason, in order to obtain a deep insight into the injected gas behaviour on an average cycle basis, the experimental investigation was supported by a numerical analysis. Simulations were carried out by an optimized variable-density finite-volume numerical model which was built within the Star-CD environment. A previously developed and validated ‘virtual injector’ model was implemented. The outcomes of the numerical model were compared to laser-induced fluorescence images, for both stratified- and homogeneous-charge engine operating conditions and a good agreement was obtained, substantiating the reliability of the applied computational model. Then, the effects of the injector protrusion in the combustion chamber and of injection timing were analyzed, and their impact on jet stability and mixture-formation process was analyzed.

Effects of Pre-Injection on Combustion Characteristics of a Single-Cylinder Diesel Engine

2009 ◽  
Author(s):  
M. Mittal ◽  
G. Zhu ◽  
T. Stuecken ◽  
H. J. Schock
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Load Condition ◽  
Combustion Characteristics ◽  
Combustion Noise ◽  
Injection Timing ◽  
Single Cylinder ◽  
Multiple Injections ◽  
Main Injection ◽  
Load Conditions

Multiple injections used for diesel engines, especially pre- and post-injections, have the potential to reduce combustion noise and emissions with improved engine performance. This paper outlines the combustion characteristics of a single-cylinder diesel engine with multiple injections. The effects of pre-injection (multi-injection) on combustion characteristics are presented in a single-cylinder diesel engine at different engine speeds and load conditions. A common rail fuel system with a solenoid injector, driven by a peak and hold circuit, is used in this work. This enables us to control the number of injections, fuel injection timing and duration, and the fuel rail pressure that can be used to optimize the engine combustion process (e.g., eliminate engine knock). Mass fraction burned and burn durations are determined by analyzing the measured in-cylinder pressure data. Results are compared with the cases when no pre-injection was used, i.e. only main injection, at the same engine speeds and load conditions. In each study, different cases are considered with the variation in main injection timing. It is found that at full-load condition and lower engine speeds pre-injection is an effective method to alter the engine burn rate and hence to eliminate knock.

Controlling Gasoline Low Temperature Combustion by Diesel Micro Pilot Injection

2011 ◽  
Author(s):  
Johannes Eichmeier ◽  
Uwe Wagner ◽  
Ulrich Spicher
Keyword(s):  
Low Temperature ◽  
Combustion Process ◽  
Pressure Rise ◽  
Reaction Rates ◽  
Pollutant Emissions ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Pilot Injection ◽  
Low Temperature Combustion ◽  
Temperature Combustion

The simultaneous reduction of fuel consumption and pollutant emissions, namely NOx and soot, is the predominant goal in modern engine development. In this context, low temperature combustion concepts are believed to be the most promising approaches to resolve the above mentioned conflict of goals. Disadvantageously these combustion concepts show high peak pressures or high rates of pressure rise due to early ignition and high reaction rates especially at high loads. Furthermore, there are still challenges in controlling combustion phasing. In this context using a small amount of pilot Diesel injected directly into the combustion chamber to ignite a highly diluted gasoline air mixture can overcome the aforementioned difficulties. As the gasoline does not ignite without the Diesel, the pilot injection timing can be used to control combustion phasing. By increasing dilution even high loads with low rates of pressure rise and without knocking are possible. This paper shows the results of experimental investigations carried out on a heavy duty boosted single cylinder Diesel engine. Based on the indicated cylinder pressure, the combustion process is characterised by performing knock analyses as well as thermodynamic analyses. Furthermore an optically accessible engine has been set up to investigate both the Diesel injection and the combustion process by means of digital high speed imaging. Together with the thermodynamic analyses the results of these optical investigations make up the base for the presented theoretical model of this combined Diesel gasoline combustion process. To show the load potential of this Dual-Fuel-CAI concept, the engine was operated at 2100 1/min with an IMEP of 19 bar. NOx emissions did not exceed 0.027 g/kWh.

scholarly journals Chemical kinetic analysis of in-cylinder ion current generation under direct water injection within internal combustion Rankine cycle engine

2021 ◽  
pp. 161-161
Author(s):  
Zhe Kang ◽  
Yang Lv ◽  
Nanxi Zhou ◽  
Lezhong Fu ◽  
Jun Deng ◽  
...  
Keyword(s):  
Initial Temperature ◽  
Water Injection ◽  
Rankine Cycle ◽  
Internal Combustion ◽  
Chemical Kinetic ◽  
Ion Current ◽  
Residual Water ◽  
Current Signal ◽  
Injection Process ◽  
Direct Water Injection

Direct water injection provides feasible solution for combustion optimization and efficiency enhancement within internal combustion Rankine cycle engine, while the feedback signal of close-loop direct water injection control is still absent. Ion current detection monitors in-cylinder electron variation which shows potential in revealing direct water injection process. For better understanding of unprecedented augment of ion current signal under direct water injection within internal combustion Rankine cycle engine, a chemical kinetic model is established to calculate the effect of intake oxygen fraction, fuel quantity, initial temperature and residual water vapor on in-cylinder electron formation based on GRI Mech 3.0 and ion current skeleton mechanism. The simulation results indicate direct water injection process show significant impact on in-cylinder electron formation through chemical interactions between H2O and other intermedia species including HO2, O2, CH3 and H, these reactions provides additional OH radical for propane oxidation facilitation, which result in large portion of CH radical formation and therefore, lead to higher in-cylinder electron generation. The initial temperature plays a vital role in determining whether residual water vapor show positive or negative effect by in-cylinder temperature coordination of direct water injection. Results of this work can be used to explain phenomenon related to direct water injection and ion current signal variation under both internal combustion Rankine cycle or traditional petrol engine.

Computational fluid dynamics investigations of the effect of water injection timing on thermal stratification and heat release in thermally stratified compression ignition combustion

2018 ◽  
Vol 20 (5) ◽  
pp. 555-569 ◽  
Author(s):  
Mozhgan Rahimi Boldaji ◽  
Aimilios Sofianopoulos ◽  
Sotirios Mamalis ◽  
Benjamin Lawler
Keyword(s):  
Heat Release ◽  
Thermal Stratification ◽  
Water Injection ◽  
Injection Pressure ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Release Process ◽  
Advanced Combustion ◽  
Direct Water Injection ◽  
Temperature Combustion

Advanced combustion concepts, like homogeneous charge compression ignition, are limited by their narrow operating range, which stems from a lack of control over the heat release process. This study explores a new advanced combustion mode, called thermally stratified compression ignition, which uses a direct water injection event to control the heat release process in low-temperature combustion. A three-dimensional computational fluid dynamics model coupled with detailed chemical kinetics is used to better understand the effects of direct water injection on thermal stratification in the cylinder and the resulting heat release process. Previous results showed that increasing the injection pressure results in a significantly broader temperature distribution due to increased evaporative cooling. In this way, direct water injection can control low-temperature combustion heat release and extend significantly the operable load range. In this study, simulations were performed over a range of start of injection timings in order to determine its effect on thermal stratification and heat release. The results show that for both low and high injection pressures advancing the start of water injection results in increased thermal stratification and reduced peak pressure and heat release rate for injections occurring after −60 °CAD. Before −60 °CAD, advancing the water injection has a varied effect on thermal stratification and heat release depending on the injection pressure and mass of the injected water.

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