Impact of Intake Induced Swirl on Combustion and Emissions on a Single Cylinder Diesel Engine

2016 ◽  
Author(s):  
Eduardo Barrientos ◽  
Ivan Bortel ◽  
Michal Takats ◽  
Jiri Vavra
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Operating Conditions ◽  
Common Rail ◽  
Injection System ◽  
Nox Emissions ◽  
Cylinder Pressure ◽  
Swirl Ratio ◽  
Single Cylinder ◽  
Optimal Values

Engine induced swirl improves mixing of fuel and air and at optimal values accelerates burn, improves the combustion stability and can decrease particulate matter (PM). However, swirl increases convective heat loss and cylinder charge loss and could increase nitrogen oxides (NOx) emissions. High intensity of swirl could impede flame development and increases emissions of total hydrocarbons (THC) and carbon monoxide (CO). Therefore, careful and smart selection of optimal swirl values is paramount in order to obtain beneficial impact on combustion and emissions performance. This study is conducted on a 0.5L single cylinder research engine with common rail (CR) diesel injection system, with parameters corresponding to modern engines of passenger cars. The engine has three separate ports in the cylinder head. The change of swirl ratio is defined by closing appropriate ports. There are three levels of swirl ratio under study — 1.7, 2.9 and 4.5, corresponding to low, medium and high swirl levels respectively. This study highlights the influence of intake induced swirl on combustion parameters and emissions. Assessed combustion parameters are, among others, heat release rate, cylinder pressure rise and indicated mean effective pressure. Assessed emissions are standard gaseous emissions and smoke, with emphasis on PM emissions. An engine speed of 1500 rpm was selected, which well represents common driving conditions of this engine size. Various common rail pressures are used at ambient inlet manifold pressure (without boost pressure) and at 1 bar boosted pressure mode. It is found that when the swirl level is increased, the faster heat release during the premixed combustion and during early diffusion-controlled combustion causes a quick increase in both in-cylinder pressure and temperature, thus promoting the formation of NOx. However, since swirl enhances mixing and potentially produces a leaning effect, PM formation is reduced in general. However, maximum peak temperature is lower for high swirl ratio and boosted modes due to the increase of heat transfer into cylinder walls. Furthermore, it is necessary to find optimal values of common rail pressures and swirl ratio. Too much mixing allows increase on PM, THC and CO emissions without decrease on NOx emissions in general. Common rail injection system provides enough energy to achieve good mixing during all the injection time in the cases of supercharged modes and high common rail pressure modes. Positive influence of swirl ratio is found at lower boost pressures, lower revolution levels and at lower engine loads. The results obtained here help providing a better understanding on the swirl effects on diesel engine combustion and exhaust emissions over a range of engine operating conditions, with the ultimate goal of finding optimal values of swirl operation.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

scholarly journals Effect of EGR on Performances and Emissions of DI Diesel Engine Fueled with Waste Plastic Oil: CDF Approach

2021 ◽  
Vol 45 (3) ◽  
pp. 217-223
Author(s):  
Khatir Naima ◽  
Younes Menni ◽  
Mounir Alliche ◽  
Giulio Lorenzini ◽  
Hijaz Ahmad ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Release Rate ◽  
Injection Timing ◽  
Nox Emissions ◽  
Cylinder Pressure ◽  
Waste Plastic ◽  
Waste Plastic Oil ◽  
Di Diesel Engine ◽  
Fraction Increase

Recently, there is an increasing interest in the pyrolysis of waste plastic into usable fuel as a friendly environment method for waste plastic disposal. The existing literature from various studies stated that the major problem related to the use of WPO in diesel engines is the high NOx emissions level. This paper aims to remedy this problem by suggesting the best EGR percentage with the advanced optimum injection timing. Primary, 5 EGR percentage fractions are considered: 0%, 5%, 15%, 20% and 25% percent. The results showed that 25% is the best percentage regarding emissions. However, a significant reduction in mean in-cylinder pressure, temperature, and heat release rate was depicted with the EGR fraction increase. Injection timing is advanced to recoup the decrease in performance. The results showed that 25% of EGR and advanced injection timing by 5 degrees would be better for performances and emissions of DI diesel engine while running with waste plastic oil as an alternative fuel.

Model-Based Optimization and Pressure Fluctuation Control of Pressure Reservoir in Electrically Controlled Fuel Injection System for Single Cylinder Diesel Engine

2017 ◽  
Author(s):  
Ke Zhang ◽  
Zhifeng Xie ◽  
Ming Zhou
Keyword(s):  
High Pressure ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Pressure Fluctuation ◽  
Fuel Injection ◽  
Common Rail ◽  
Installation Space ◽  
Injection System ◽  
Fuel Injection System ◽  
Single Cylinder

Single-cylinder diesel engines usually employ mechanically actuated or time-type electrically controlled fuel injection systems. But due to the lack of flexibility to provide high pressure and fully varying injection parameters, fuel efficiency and emissions are poor. Although modern multi-cylinder engines have employed high pressure common rail fuel injection system for a long time, this technology has not been demonstrated in single-cylinder diesel engines. Due to the small installation space and little fuel injection amount of single cylinder diesel engine, high pressure common rail fuel injection system cannot be employed directly. In this study an electrically controlled high pressure fuel injection system of time-pressure-type (PTFS) for single-cylinder diesel engine was demonstrated. PTFS integrated the fuel pump and pressure reservoir (PR) to reduce installation space, which enabled it to match various kinds of single-cylinder diesel engines. However, the volume of the PR of PTFS is still limited, leading to obvious pressure fluctuation induced by periodic fuel pumping and injection. Pressure fluctuation might affect the stability and consistency of fuel injection, deteriorating the combustion and emissions of the engine further. This work established a mathematical model for the system, and studied the effect of the main parameters of the PR to the pressure fluctuations in the PR. The structure and dimensions of the system were optimized and a damping mechanism was proposed to reduce the pressure fluctuation. The optimized pressure fluctuation of PTFS achieved an acceptable level which can support steady and effective fuel injection. As a result, the fuel consumption efficiency and emission level of single cylinder diesel engine were enhanced.

scholarly journals Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Fuqiang Bai ◽  
Zuowei Zhang ◽  
Yongchen Du ◽  
Fan Zhang ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Combustion Process ◽  
Injection Rate ◽  
Injection System ◽  
Nox Emissions ◽  
Release Process ◽  
Common Rail Injection System ◽  
Soot Emissions ◽  
Rate Profile

When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.

Effect of Swirl and Injection Pressure on Performance and Emissions of JP-8 Fueled High Speed Single Cylinder Diesel Engine

2010 ◽  
Author(s):  
Jagdish Nargunde ◽  
Chandrasekharan Jayakumar ◽  
Anubhav Sinha ◽  
Naeim A. Henein ◽  
Walter Bryzik ◽  
...  
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Fuel Injection ◽  
Combustion Engine ◽  
Combustion Process ◽  
Combustible Mixture ◽  
Injection System ◽  
Swirl Ratio ◽  
Single Cylinder ◽  
Injection Pressures

An investigation was conducted on a 0.42 liter single cylinder diesel engine equipped with a common rail fuel injection system to evaluate the influence of the swirl motion on JP-8 fuel combustion. Engine tests were performed under steady state conditions of 5 bar IMEP and 1500 RPM. Two different swirl ratios of 1.44 and 7.12 were applied at injection pressures ranging from 400 to 1200 bar. The apparent rate of heat release (ARHR) curve is analyzed to determine the effect of swirl on combustible mixture formation, auto-ignition, premixed and diffusion controlled combustion fractions. An attempt is made to correlate between the swirl ratio and different combustion and emissions parameters at different injection pressures. The emissions included the gaseous fractions and particulates. Two types of particulate matter were measured: Accumulation mode particles (AMPs) and Nucleation mode particles (NMPs). The results indicate that ignition delay duration of JP-8 increases as the swirl ratio increases influencing the overall combustion process and engine out emissions.

Development of a Real-Time NOx Prediction Model Based on Heat Release Analysis in a Direct-Injection Diesel Engine

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Dong Wang ◽  
Chao Zhang
Keyword(s):  
Diesel Engine ◽  
Prediction Model ◽  
Heat Release ◽  
Real Time ◽  
Heat Release Rate ◽  
Release Rate ◽  
Direct Injection ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Direct Injection Diesel Engine

A prediction model, which describes linear relationship between the nitrogen oxides (NOx) emissions and the in-cylinder heat release rate in a direct-injection diesel engine, was developed through numerical simulations. A modified KIVA-3 V code was used to calculate NOx formations and to conduct heat release analyses in a direct-injection diesel engine under different operating conditions. The numerical simulation results indicated that the NOx formation amount was related to both the magnitude and the timing of the peak heat release rate in each engine cycle. Based on the above observations, a control-oriented dynamic NOx model was constructed and then implemented into a feedback emission control system on a small diesel engine. A new parameter—combustion acceleration—was proposed in this research to describe the intensity of the premixed combustion. Experimental work was also conducted to measure the real-time in-cylinder pressure at each crank-angle when the engine was running and the heat release rate was calculated instantaneously to control an exhaust gas recirculation (EGR) valve. The experimental results showed that the proposed NOx prediction model was effective in controlling NOx emissions under high rpm conditions.

Modeling and validation of crankshaft speed fluctuations of a single-cylinder four-stroke diesel engine

2021 ◽  
pp. 095440702110262
Author(s):  
Mustafa Babagiray ◽  
Hamit Solmaz ◽  
Duygu İpci ◽  
Fatih Aksoy
Keyword(s):  
Diesel Engine ◽  
Dynamic Model ◽  
Moment Of Inertia ◽  
Mass Motion ◽  
Cylinder Pressure ◽  
Motion Equations ◽  
Single Cylinder ◽  
Mass Moment ◽  
Mass Moment Of Inertia ◽  
Speed Fluctuations

In this study, a dynamic model of a single-cylinder four-stroke diesel engine has been created, and the crankshaft speed fluctuations have been simulated and validated. The dynamic model of the engine consists of the motion equations of the piston, conrod, and crankshaft. Conrod motion was modeled by two translational and one angular motion equations, by considering the kinetic energy resulted from the mass moment of inertia and conrod mass. Motion equations involve in-cylinder gas pressure forces, hydrodynamic and dry friction, mass inertia moments of moving parts, starter moment, and external load moment. The In-cylinder pressure profile used in the model was obtained experimentally to increase the accuracy of the model. Pressure profiles were expressed mathematically using the Fourier series. The motion equations were solved by using the Taylor series method. The solution of the mathematical model was performed by coding in the MATLAB interface. Cyclic speed fluctuations obtained from the model were compared with experimental results and found compitable. A validated model was used to analyze the effects of in-cylinder pressure, mass moment of inertia of crankshaft and connecting rod, friction, and piston mass. In experiments for 1500, 1800, 2400, and 2700 rpm engine speeds, crankshaft speed fluctuations were observed as 12.84%, 8.04%, 5.02%, and 4.44%, respectively. In simulations performed for the same speeds, crankshaft speed fluctuations were calculated as 10.45%, 7.56%, 4.49%, and 3.65%. Besides, it was observed that the speed fluctuations decreased as the average crankshaft speed value increased. In the simulation for 157.07, 188.49, 219.91, 251.32, and 282.74 rad/s crankshaft speeds, crankshaft speed fluctuations occurred at rates of 10.45%, 7.56%, 5.84%, 4.49%, and 3.65%, respectively. The effective engine power was achieved as 5.25 kW at an average crankshaft angular speed of 219.91 rad/s. The power of friction loss in the engine was determined as 0.68 kW.

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