Browse Topic: Dual fuel engines

Items (765)

9/23/2020

This SAE Aerospace Information Report (AIR) is intended as a source of comparative information and is subject to change to keep pace with experience and technical advances. This document describes currently used fuels and fuels which may be used in the future. Conventional gasoline and diesel fuels are intentionally omitted from this document.

AGE-3 Aircraft Ground Support Equipment Committee

Optical Characterization of the Combustion Process inside a Large-Bore Dual-Fuel Two-Stroke Marine Engine by Using Multiple High-Speed Cameras

2020-01-07884/14/2020

Dual-fuel engines for marine propulsion are gaining in importance due to operational and environmental benefits. Here the combustion in a dual-fuel marine engine operating on diesel and natural gas, is studied using a multiple high-speed camera arrangement. By recording the natural flame emission from three different directions the flame position inside the engine cylinder can be spatially mapped and tracked in time. Through space carving a rough estimate of the three-dimensional (3D) flame contour can be obtained. From this contour, properties like flame length and height, as well as ignition locations can be extracted. The multi-camera imaging is applied to a dual-fuel marine two-stroke engine, with a bore diameter of 0.5 m and a stroke of 2.2 m. Both liquid and gaseous fuels are directly injected at high pressure, using separate injection systems. Optical access is obtained using borescope inserts, resulting in a minimum disturbance to the cylinder geometry. In this type of engine, with fuel injection from positions at the rim of the cylinder, the flame morphology becomes asymmetric. The optical spatial mapping and tracking method is demonstrated to be well suited for the study of such an asymmetric combustion system. Spatial mapping and tracking of flame position is applied to both engine operating modes; normal diesel operation and dual-fuel operation with diesel pilot ignition of the gas. Similarities and differences between diesel and gas flame shape and development can thus be visualised directly. The effects of changing charge density, gas injection pressure and injection nozzle geometry on the flame geometry and development are also studied.

Hult, Johan, Matamis, Alexios, Baudoin, Eric, Mayer, Stefan, Richter, Mattias

Experimental Investigation of Multiple Injection Strategies on Combustion Stability, Performance and Emissions in a Methanol-Diesel Dual Fuel Non-Road Engine

2020-01-03084/14/2020

In this work methanol was port injected while diesel was injected using a common rail system in a single cylinder non-road CI engine. Experiments were conducted with single (SPI) and double (DPI - pilot and main) injection of the directly injected diesel at 75% load and at a constant speed of 1500 rpm. The effects of methanol to diesel energy share (MDES) and injection scheduling on combustion stability, efficiency and emissions were evaluated. Initially, in the SPI mode, the methanol to diesel Energy Share (MDES) was varied, while the injection timing of diesel was always fixed for best brake thermal efficiency (BTE). Increase in the MDES resulted in a reduction in NOx and smoke emissions because of the high latent heat of vaporization of methanol and the oxygen available. Enhanced premixed combustion led to a raise in brake thermal efficiency (BTE). Coefficient of variation of IMEP, peak pressure and BTE were deteriorated which limited the usable MDES to 43%. DPI of diesel i.e. early pilot for enhancing the reactivity of the charge along with main injection for combustion phasing, was then applied at a fixed diesel quantity corresponding to an MDES of about 50%. The injection timings of the pilot and main and their relative quantities were varied and optimized based on the BTE. An increase in the pilot quantity improved the combustion stability and the values of COV of IMEP were lesser than 2%. When compared to neat diesel operation, SPI at 50% MDES reduced NOx and smoke emissions by 49% and 91% respectively. Further reductions in NOx by 14.5% and enhancement in MDES to about 53% along with improved combustion stability were possible with DPI.

Panda, Kasinath, Ramesh, A.

Numerical Investigation of the Combustion Kinetics of Partially Premixed Combustion (PPC) Fueled with Primary Reference Fuel

2020-01-0554

4/14/2020

This work numerically investigates the detailed combustion kinetics of partially premixed combustion (PPC) in a diesel engine under three different premixed ratio fuel conditions. A reduced Primary Reference Fuel (PRF) chemical kinetics mechanism was coupled with CONVERGE-SAGE CFD model to predict PPC combustion under various operating conditions. The experimental results showed that the increase of premixed ratio (PR) fuel resulted in advanced combustion phasing. To provide insight into the effects of PR on ignition delay time and key reaction pathways, a post-process tool was used. The ignition delay time is related to the formation of hydroxyl (OH). Thus, the validated Converge CFD code with the PRF chemistry and the post-process tool was applied to investigate how PR change the formation of OH during the low-to high-temperature reaction transition. The reaction pathway analyses of the formations of OH before ignition time were investigated. It was found that in the case of PR0%, the second isomerization from C7H14OOH2-4O2 to NC7KET24 and the decomposition of NC7KET24 contributed 27.6% and 46.46% of OH formation respectively. The contribution of AC8H16OOH-B to the formation of OH was just 12.13%. It can be concluded that the low temperature oxidation reactions of n-heptane were key steps in producing OH. While in the cases of PR30% and PR50%, because of the higher in-cylinder temperature, most of OH derived from the decomposition reaction of H2O2 that contributed 54.47% and 54.63% of OH formation respectively. Besides, in the PR30% and PR50%, the oxidation reactions of IC4H7 contributed 31.95% and 33.84% of OH formation respectively, and the oxidation reaction of IC4H6OH contributed 19.08% and 22.22% of OH formation respectively, which indicated that the oxidation of iso-octane also contributed to the production of OH. In addition, the distributions of mass fraction, production rate and representative creation reaction (RCR) of OH showed that in the case of PR30% and PR50%, the formation of OH outside the spray periphery were dominated by the reactions R394 (H2O2 (+ M) <=> 2 OH (+ M)), while that in the spray periphery were predominantly controlled by the reaction R21 (NC7KET24 => NC3H7CHO + CH3COCH2 + OH) and R125 (IC4H6OH + HO2 <=> CH2CCH2OH + CH2O + OH). Premixed fuel from port injection changed the formation pathway of OH during the oxidation of direct injection fuel through the reaction R125.

Zhao, Yuanyuan, Wang, Hu, Liu, Xinlei, Liu, Daojian, Chenchen, Wang, Zhu, Hongyan, Zheng, Zunqing, Yao, Mingfa

Performance and Noise of Dual Fuel Engine Running on Cottonseed, Soybean Raw Oils and Their Methyl Esters as Pilot Fuels

2020-01-0811

4/14/2020

The cottonseed oil, soybean oil and their methyl esters have been used as a pilot fuels for dual fuel engine running on the LPG as the main fuel. A variable compression research diesel engine has been converted to run on dual fuel of LPG and a pilot fuel derived from the renewable liquid fuels above. The engine has been instrumented to measure the combustion pressure, crank angles, exhaust temperature, flow rates of air, pilot fuel and gaseous fuel. The effects of changing the following parameters have been studied: the mass of pilot fuel, the mass of gaseous fuel, the pilot fuel injection timing, engine speed and the pilot fuel type. Five different pilot fuels has been tested here namely the cottonseed raw oil, the cottonseed methyl ester, the soybean raw oil, the soybean methyl ester and the diesel fuel as a reference fuel. The results presented included the combustion noise (as maximum pressure rise rate), the heat release rate, the maximum combustion pressure, the exhaust temperature, the brake and indicated mean effective pressures. It has been found that the renewable pilot fuel properties affected the combustion process and the combustion noise. The best fuel in terms of highest output and minimum noise has been put forward.

Selim, Mohamed Y. E., Saleh, Hosam E.

Effective Utilization of Low Carbon Fuels in Agricultural Engines Using Low Cost Electronic Primary Fuel Injection Unit

2020-01-1369

4/14/2020

Reliability and cost effectiveness of electronics demands its usage in all the wings of science and technology. Thus an attempt was made in this work to investigate the potential of using electronics for injecting primary fuel for the compression ignition engine used by farmers for agricultural purpose. In the first phase of the work, a new Electronic Control Unit (ECU) for primary fuel injection was developed and tested for its repeatability on fuel injection quantity for the different input voltages. Test engine was developed and tested under various load condition for its performance, emission, and combustion characteristics with neat diesel and Waste Cooking Oil Methyl Esters (WCOME) as baseline readings in the second phase of the work. In the third phase of work, the developed engine was modified to operate in duel fuel mode with developed ECU. In this work, ethanol was chosen as primary fuel due to its availability and less toxic nature as compared to other green fuels. Pilot fuel (i.e. WCOME) was injected using mechanical fuel injection system. Results inferred that the brake thermal efficiency was increased by 33.33% with newly developed injection system. The results also inferred that harmful carbon based emissions were simultaneously reduced with the modified engine because of the precise metering of primary fuel using ECU. On the point of commercialization, cost involved in developing the new ECU was found to be very low as compared to conventional fuel injection system. In addition to the above point, developed duel fuel engine with ECU also helped in the utilization of renewable energy resources like ethanol and WCOME, as fuel in diesel engine which indirectly helps in the effective waste management of molasses from the sugar industry as well as waste cooking oil. Hence it can be concluded that, the low cost duel fuel compression ignition engine has great potential in future for agricultural purpose.

Nandagopal, Sasikumar, Anaimuthu, Shridhar, Mayakrishnan, Jaikumar, Raja, Selvakumar, Busireddy, Vamshidhar, Kovuru, Madhu

Development of Dual Fuel Engine Fueled with Used Cooking Oil Biodiesel and Ethanol-an Experimental Study on Performance and Combustion Characteristics

2020-01-0803

4/14/2020

This paper investigates the performance and combustion characteristics of a compression ignition engine (CI engine) fueled with Used Cooking Oil Biodiesel (UCOB) and ethanol in dual fuel mode. In this study, UCOB was injected as the main fuel through a conventional mechanical fuel injection system. Various mass flow rates of ethanol were inducted as primary fuel through the engine intake manifold using a separate fuel injection system. Mass flow rates of ethanol were metered by an electronic control circuit. The engine test was conducted under different load conditions from no load to full load in a fully instrumented direct injection, water-cooled compression ignition engine. The results indicated that the dual fuel engine produced higher brake thermal efficiency, cylinder pressure, heat release rate with lower specific fuel consumption at a higher load condition. However, it was found that combustion characteristics improved marginally at the lower load conditions.

Velmurugan, Ramanathan, Mayakrishnan, Jaikumar, Palanimuthu, Vijayabalan, Nandagopal, Sasikumar, Elumalai, Sangeethkumar, Anaimuthu, Shridhar, Busireddy, Vamshidhar

A Real-Time Capable and Modular Modeling Concept for Virtual SI Engine Development

2020-01-05774/14/2020

Spark Ignited (SI) combustions engines in combination with different degrees of hybridization are expected to play a major role in future vehicle propulsion. Due to the combustion principle and the related thermodynamic efficiency, it is especially challenging to meet future CO2 targets. The layout and optimization of the overall system requires novel methods in the development process which feature a seamless transition between real and virtual prototypes. Herein, engine models need to predict the entire engine operating range in steady-state and transient conditions and must respond to all relevant control inputs. In addition, the model must feature true real-time capability. This work presents a holistic and modular modeling framework, which considers all relevant processes in the complex chain of physical effects in SI combustion. The basis is a crank-resolved cylinder model which describes gas exchange and compression to determine the thermodynamic state and turbulence conditions at spark-advance. Ignition and flame front combustion are modeled by a mechanistic, quasi-dimensional combustion model with a detailed consideration of combustion chamber geometry for flame-wall interaction. Cycle-to-cycle variations are imposed in a semi-empirical manner in order to provide realistic boundary conditions for the thermo-chemical knock model. The models are validated against engine measurements for a passenger car sized TGDI engine in a wide range of operating conditions covering the entire engine map. Emphasis is put on comparing pressure and heat release traces, not only for the mean cycle, but for the range of stochastic variations of 100 measured cycles. The validation results confirm a good level of agreement between measured and simulated results. To demonstrate capabilities of the proposed modeling concept, a model-based optimization is performed in a computational study, aiming at an optimization of engine efficiency under knocking constraints. The study examines two motoric measures, namely water injection and variable compression ratio. Finally, the optimized model runs in a transient drivecycle simulation. The test is performed on a HiL system to prove the model’s real-time capability.

Poetsch, Christoph, Wurzenberger, Johann, Katrasnik, Tomaz

Experimental and 1D Numerical Investigations on the Exhaust Emissions of a Small Spark Ignition Engine Considering the Cylinder-by-Cylinder Variability

2020-01-05784/14/2020

This paper reports a numerical and experimental analysis on a twin-cylinder turbocharged Spark Ignition engine carried out to investigate the cylinder-to-cylinder variability in terms of performance, combustion evolution and exhaust emissions. The engine was tested at 3000 rpm in 20 different steady-state operating conditions, selected with the purpose of observing the influence of cylinder-by-cylinder A/F ratio variations and the EGR effects on the combustion process and exhaust emissions for low to medium/high loads. The experimental outcomes showed relevant differences in the combustion evolution (characteristic combustion angles) between cylinders and not negligible variations in the emissions of the single cylinder exhaust and the overall engine one. This misalignment resulted to be due to differences in the injected fuel amount by the port injectors in the two cylinders, mainly deriving from the specific fuel rail geometry. The experimental data were then used to validate a 1D engine model, integrated with refined sub-models of turbulence, combustion, heat transfer and emissions. The model takes into account the in-cylinder production of noxious species, and their propagation in the exhaust system, up to the three-way catalytic converter. A satisfactory accuracy was reached in reproducing the overall engine performance and the combustion process in the two cylinders. In particular, the emission sub-models confirmed that the variations of the cylinder-out exhaust emissions (NOx, HC and CO) were mainly due to the non-uniform effective in-cylinder A/F ratio. The proposed numerical methodology has the potential to highlight unexpected combustion non-uniformities among different cylinders and represents a powerful support to the engine design and development. It also allows for the prediction of the overall exhaust emissions at different engine operating conditions up to the entire domain, thus assisting the engine calibration phase and reducing the experimental efforts.

Marchitto, Luca, Teodosio, Luigi, Tornatore, Cinzia, Valentino, Gerardo, Bozza, Fabio

Experimental Investigation of Combustion Stability and Particle Emission from CNG/Diesel RCCI Engine

2020-01-08104/14/2020

This paper presents the experimental investigation of combustion stability and nano-particle emissions from the CNG-diesel RCCI engine. A modified automotive diesel engine is used to operate in RCCI combustion mode. An open ECU is used to control the low and high reactivity fuel injection events. The engine is tested for fixed engine speed and two different engine load conditions. The tests performed for various port-injected CNG masses and diesel injection timings, including single and double diesel injection strategy. Several consecutive engine cycles are recorded using in-cylinder combustion pressure measurement system. Statistical and return map techniques are used to investigate the combustion stability in the CNG-diesel RCCI engine. Differential mobility spectrometer is used for the measurement of particle number concentration and particle-size and number distribution. It is found that advanced diesel injection timing leading to higher cyclic combustion variations. Too advanced diesel injection results in a partial burn/misfire operating condition. The results indicate that the double diesel injection strategy has a relatively higher concentration of nucleation mode particles and it increases with advancing the diesel injection timings. Typical bimodal lognormal shape of particle-size and number distribution curve is shifted to uni-modal shape by increasing the mass of port-injected fuel.

Saxena, Mohit Raj, Maurya, Rakesh Kumar

Study on the Effect of Manifold Induction of Acetylene in a Dual-Fuelled CI Engine

2020-01-08174/14/2020

The utilization of gaseous fuels in internal combustion (IC) engines is receiving more significant greater interest in recent years because of their better fuel mixing characteristics. Apart from potential gaseous fuels such as liquefied natural gas (LPG), compressed natural gas (CNG), and hydrogen, other alternatives are being explored for their utilization in IC engines. The reason for this exploration is mainly because of the durability and robust nature of compression ignition (CI) engines, and more research focuses on the utilization of a variety of gaseous fuels in CI engines. However, gaseous fuels need to be used in CI engines on dual fuel mode only. In this investigation, a single-cylinder, four-stroke, air-cooled diesel engine was converted into Acetylene run dual-fuel CI engine by changing the intake manifold of the test engine. Acetylene at three flow rates viz., 2lpm, 4lpm, and 6lpm were introduced into the intake port by manifold induction technique while Jatropha biodiesel/diesel was injected directly into the cylinder. In this paper, the effect of manifold induction of Acetylene on the performance and emission characteristics of the test engine was assessed and compared with those of conventional diesel operation of the test engine.

Sahoo, Rakesh Kumar, Jaiswal, Akshat, Sivalingam, Murugan

On Maximizing Argon Engines' Performance via Subzero Intake Temperatures in HCCI Mode at High Compression Ratios

2020-01-11334/14/2020

The improvement of the indicated thermal efficiency of an argon power cycle (replacing nitrogen with argon in the combustion reaction) is investigated in a CFR engine at high compression ratios in homogeneous charge compression ignition (HCCI) mode. The study combines the two effects that can increase the thermodynamic efficiency as predicted by the ideal Otto cycle: high specific heat ratio (provided by argon), and high compression ratios. However, since argon has relatively low heat capacity (at constant volume), it results in high in-cylinder temperatures, which in turn, leads to the occurrence of knock. Knock limits the feasible range of compression ratios and further increasing the compression ratio can cause serious damage to the engine due to the high pressure rise rate caused by advancing the combustion phasing. The technique proposed in this study in order to avoid intense knock of an argon cycle at high compression ratios is to cool the intake charge to subzero temperatures which leads to lower in-cylinder temperatures and hence, less possibility of having knock. The main variable in this study was the intake temperature which was investigated at 40.0 °C and -6.0 °C which corresponded to low and high compression ratios, respectively. Emission analysis shows that the low in-cylinder temperature of the cooled case led to less complete combustion, and so, lower combustion efficiency. Since nitrogen is replaced with argon, NOx was only formed in negligible amounts due to some nitrogen traces in the used gasses cylinders. Furthermore, the cooled charge required more work to be done in the gas exchange process due to the decrease in the intake pressure caused by cooling the intake which deteriorated the gas exchange efficiency. The heat losses factor was found to be the main parameter that dictated the improvement of the thermodynamic efficiency and it was found that the indicated thermal efficiency was deteriorated for the cooled case as a result of all the aforementioned factors. Although the values of the thermodynamic efficiency at high compression ratios did not meet the expectations based on the ideal Otto cycle due to the assumptions of the ideal cycle, the obtained values, in general, are relatively high.

Elkhazraji, Ali, Mohammed, Abdulrahman, Jan, Sufyan, Masurier, Jean-Baptiste, Dibble, Robert, Johansson, Bengt

Numerical Investigation of the Effects of Port Water Injection Timing on Performance and Emissions in a Gasoline Direct Injection Engine

2020-01-02874/14/2020

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. A thorough investigation of the port water injection technique is required to fully understand its effects on the engine combustion process. This study explores the potential of the port water injection technique in improving the performance of a turbo charged Gasoline Direct Injection engine. 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. The pressure oscillation is also suppressed which indicates a better knocking resistance for water injection strategy. An optimized injection timings could be found for a particular load condition and also lead to a better combustion performance and emissions.

Yin, Peng, Li, Xuesong, Hung, David, Fan, Yadong, Xu, Min

Numerical Investigation of Diesel-Spray-Orientated Piston Bowls on Natural Gas and Diesel Dual Fuel Combustion Engine

2020-01-03114/14/2020

Low combustion efficiency and high hydrocarbon emissions at low loads are key issues of natural gas and diesel (NG-diesel) dual fuel engines. For better engine performance, two diesel-spray-orientated (DSO) bowls were developed based on the existing diesel injector of a heavy-duty diesel engine with the purpose of placing more combustible natural gas/air mixture around the diesel spray jets. A protrusion-ring was designed at the rim of the piston bowl to enhance the in-cylinder flame propagation. Numerical simulations were conducted for a whole engine cycle at engine speed of 1200 r/min and indicated mean effective pressure (IMEP) of 0.6 MPa. Extended coherent flame model 3 zones (ECFM-3Z) combustion model with built-in soot emissions model was employed. Simulation results of the original piston bowl agreed well with the experimental data, including in-cylinder pressure and heat released rate (HRR), as well as soot and methane emissions. Turbulence kinetic energy, IMEP and methane emissions of the DSO piston geometries were compared with that of the original piston geometry. The results showed that both in-cylinder pressure and heat release rate of both DSO piston geometries increased due to higher turbulence kinetic energy comparing to the original piston geometry while methane emissions significantly decreased. Methane combustion with the DSO piston geometries tended to occur far away from the piston center compared to that with the original piston design at the same crank angle due to the protrusion-ring at the rim of piston bowl. Overall, the methane combustion with the DSO pistons was enhanced in the whole combustion chamber, which led to improved combustion efficiency and lower methane emissions.

Shen, Zhaojie, Wang, Xinyan, Zhao, Hua, Shen, Yitao, Yang, Jianguo

An Investigation of the Effects of the Piston Bowl Geometries of a Heavy-Duty Engine on Performance and Emissions Using Direct Dual Fuel Stratification Strategy, and Proposing Two New Piston Profiles

03-13-03-00213/16/2020

Direct dual fuel stratification (DDFS) strategy benefits the advantages of the RCCI and PPC strategies simultaneously. DDFS has improved control over the heat release rate, by injecting a considerable amount of fuel near TDC, compared to RCCI. In addition, the third injection (near TDC) is diffusion-limited. Consequently, piston bowl geometry directly affects the formation of emissions. The modified piston geometry was developed and optimized for RCCI by previous scholars. Since all DDFS experimental tests were performed with the modified piston profile, the other piston profiles need to be investigated for this strategy. In this article, first, a comparative study between the three conventional piston profiles, including the modified, stock, and scaled pistons, was performed. Afterward, the gasoline injector position was shifted to the head cylinder center for the stock piston. NOX emissions were improved; however, soot was increased slightly. The other emissions, in-cylinder pressure, and AHRR remained unchanged. Finally, the advantages of modified and stock pistons were combined, and two new piston profiles based on the effective geometrical parameters were proposed and investigated. The first-proposed piston profile offered better NOX and CO emissions compared to the other profiles. In addition, the gross thermal efficiency of this profile is at high levels.

Shirvani, Sasan, Shirvani, Saeid, Shamekhi, Amir H., Reitz, Rolf D.

A Time-Saving Methodology for Optimizing a Compression Ignition Engine to Reduce Fuel Consumption through Machine Learning

03-13-02-00192/7/2020

Applying a suitable design optimization technique is a crucial task for optimizing compression ignition engines because of the time-consuming process of optimization even with advanced supercomputers. Traditional computational fluid dynamics (CFD) used in conjunction with design of experiment (DOE) methods requires executing the CFD model several times. A response surface is usually fitted to relate the inputs to the outputs, which is often created based on linear regression. This method is not well suited to capture interaction effects between inputs and nonlinearities existing during engine combustion. A combination of genetic algorithm (GA) and CFD tools usually eventuates better optimum results. However, the CFD simulations must be executed sequentially, resulting in extremely high computational times, which makes it impossible to apply an optimization study using a single desktop computer. The current study examines a novel approach, which combines CFD, GA, and a type of machine learning approach, namely artificial neural networks (ANNs), in order to optimize a compression ignition engine to achieve its minimum indicated specific fuel consumption (ISFC). Start of injection (SOI) timing and input pressure were selected as the optimization variables in order to investigate improvement in ISFC without any hardware modifications of the engine. Maximum in-cylinder peak pressure and ringing intensity (pressure rise rate) were chosen as the optimization constraints. Conducting a reliable optimization study with a single desktop computer in a shorter time can be achieved by using the proposed methodology. The results indicate that a 97% decrease in the estimated number of days to achieve the final results was obtained, compared to the traditional CFD-GA approach. Furthermore, adopting this methodology eliminates the necessity for additional response surface fitting to GA data. Therefore, it facilitates an examination of design parameter effects on the engine outputs, doing sensitivity analysis, post-processing the optimization results, and providing a powerful tool to gain optimum designs. The final optimum point illustrates a 10% improvement in ISFC, while avoiding sensitive regions and without exceeding optimization constraints.

Rahnama, Pourya, Arab, Majid, Reitz, Rolf D.

Experimental Comparison of Biogas and Natural Gas as Vibration, Emission, and Performance in a Diesel Engine Converted to a Dual Fuel

04-13-01-00041/27/2020

Biogas, natural gas, and their usage in the diesel engine will be important in the future. For this purpose, the effects of biogas on engine performance, emissions, and engine vibrations of the diesel engines with dual fuel system are investigated in comparison with natural gas. It has also been included in evaluating the deformation of the engine oil due to hydrogen sulfide combustion reactions. In this study, a constant speed, naturally aspirated, and direct injection of the diesel engine with volume of 2.5 liter has been converted into a dual fuel system that can be included in gas fuels. In order to determine engine performance, exhaust emissions, engine vibration, and noise, the tests were carried out at load stages of 5, 10, 15, 20, and 25 kW and at a constant speed of 1500 rpm. The experiments were first performed in a mono operation condition of the conventional diesel fuel. Subsequently, tests were repeated under natural gas/diesel and biogas/diesel dual fuel operation conditions, respectively. As a result of the tests, it was observed that the vibration amount decreased and the noise emission was reduced by 3.5% in all stages where biogas was used as the main fuel. Depending on fuel or operation system change, no significant change was observed in cylinder block, cylinder heat, exhaust, and intake manifold temperature. The exhaust gas temperature is measured to be lower because of the carbon dioxide (CO2) content in the biogas. When approaching from the point view of engine emissions, it was determined that the carbon monoxide (CO) emission increased at all engine loads while a decrease of 50% in oxides of nitrogen (NOx) emission occurred.

Aytav, Emre, Koçar, Günnur, Teksan, Abdulhalik Emre

Development of a 3D-CFD Model for a Full Optical High-Pressure Dual-Fuel Engine

03-13-02-00171/27/2020

In times of ever stricter exhaust emission regulations, the importance of alternative combustion processes in internal combustion engines continues to grow. One approach to create a combustion progress which produces low CO2, soot, and methane emissions is the “High-Pressure Dual-Fuel” (HPDF)-combustion. Here, the direct-injected methane is ignited by a small amount of pilot-diesel and burns in a diffusive combustion mode. This study describes the development of a three-dimensional computational fluid dynamics (3D-CFD) model for the HPDF-combustion. A Reynolds-Averaged Navier-Stokes (RANS) approach with k-epsilon modelling for turbulence was chosen for the calculation of the flow field. The pilot fuel injection is implemented by using Lagrangian Particle Methods, whereas the gas injection is a mass flow boundary which is derived from measurements of the injector. The model is validated using data from a fully optically accessible single-cylinder research engine. The flow field is compared with particle image velocimetry (PIV) data taken before the start of injection (SOI). Concerning pilot injection, a grid convergence study is conducted and an optimization is developed to reduce computational costs. The penetration length of the liquid fuel spray is validated against Mie-scattering images which are taken during the “Pilot-Diesel-only” experiments in the fully optical single-cylinder research engine. The ignition and combustion is modeled via detailed chemistry, which is solved using the commercial Software CONVERGE and the SAGE chemistry solver. The flame liftoff length of the pilot-diesel and the ignition and combustion of the underexpanded gas jets are validated using high-speed imaging of flame luminosity and OH* chemiluminescence. It can be shown that the used n-heptane mechanism is capable of correctly reproducing the trends in the ignition and combustion process.

Frankl, Stephanie, Gleis, Stephan

Influence of the Kind of Fuel Kind in the Ignition of Diesel Dual Fuel Operation with Introduced Natural Gas Combining EGR and Supercharging

2019-32-0581

1/24/2020

A number of studies in diesel dual fuel (DDF) operation which introduces natural gas from the intake pipe and ignites it by a diesel fuel injection in the combustion chamber have been conducted using conventional diesel engines. The present study investigated the influence of the ignition fuel on engine performance, combustion characteristics, and emissions with a combination of EGR and supercharging in DDF operation. The experiments employed iso-pentanol blended fuels for the ignition. Isopentanol is a next generation bio-alcohol fuel produced from cellulosic biomass, and actual use can be expected. The experiments were conducted at two CNG supply rates, 0% (ordinary diesel operation) and at a 40±4% (DDF operation) energy basis, and with EGR rates varied from 0 to 26%. The boost pressure was set at two conditions, 100 kPa (naturally aspirated, N/A) and 120 kPa (supercharged, S/C) with a supercharger. Four kinds of ignition fuels were used, JIS No.2 diesel fuel as a reference, neat methyl laurate (LME) which is a major component of coconut oil biodiesel, and two iso-pentanol blended fuels with 30% mass ratios, DiP30 (70% diesel and 30% iso-pentanol) and LiP30 (70% LME and 30% iso-pentanol). The results showed that regardless of the ignition fuel, the DDF operation with EGR and also supercharging resulted in substantial reductions in NOx and smoke emissions. However, the brake thermal efficiency decreased with increasing EGR rates, and with much longer ignition delays this tendency was more pronounced for the two iso-pentanol blends.

Yoshimoto, Yasufumi, Kinoshita, Eiji, Otaka, Takeshi