| 1. |
- Golovitchev, Valeri, 1945, et al.
(författare)
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Modeling of Combustion and Emissions Formation in Heavy Duty Diesel Engine Fueled by RME and Diesel Oil
- 2009
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Ingår i: SAE Technical Papers. - 0148-7191 .- 2688-3627. ; , s. 1-13
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Konferensbidrag (refereegranskat)abstract
- A comparative study on engine performance and emissions (NOx, soot) formation has been carried out for the Volvo D12C diesel engine fueled by Rapeseed Methyl Ester, RME and conventional diesel oil. The fuel and combustion models used in this paper are the modifications of those described in [1-3]. The numerical results for different load cases illustrate that for both fuels nearly 100% combustion efficiency was predicted; in the case of RME, the cumulative heat release was compared with the RME LHV, 37.2 kJ/g. To minimize soot and NOx emissions, 25-30% EGR levels depending on the engine loads and different injection timings were analyses. To illustrate the optimal engine performance conditions, a special technique based on the time-transient parametric -T maps [4] has been used.
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| 2. |
- Golovitchev, Valeri, 1945, et al.
(författare)
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Modeling of combustion and emissions formation in heavy duty diesel engine fueled by RME and diesel oil
- 2010
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Ingår i: SAE International Journal of Engines. - : SAE International. - 1946-3944 .- 1946-3936. ; 2:2, s. 355-367
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study on engine performance and emissions (NOx, soot) formation has been carried out for the Volvo D12C diesel engine fueled by Rapeseed Methyl Ester, RME and conventional diesel oil. The fuel and combustion models used in this paper are the modifications of those described in [1-3]. The numerical results for different load cases illustrate that for both fuels nearly 100% combustion efficiency was predicted; in the case of RME, the cumulative heat release was compared with the RME LHV, 37.2 kJ/g. To minimize soot and NOx emissions, 25-30% EGR levels depending on the engine loads and different injection timings were analyses. To illustrate the optimal engine performance conditions, a special technique based on the time-transient parametric φ-T maps [4] has been used
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| 3. |
- Andersson, Björn O, 1982, et al.
(författare)
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A Modified TAB Model for Simulation of Atomization in Rotary Bell Spray Painting
- 2013
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Ingår i: Journal of Mechanical Engineering and Automation. - 2163-2413. ; 3:2, s. 54-61
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Tidskriftsartikel (refereegranskat)abstract
- The Rotary bell spray applicator technique is commonly used in the automotive industry for paint application because of its high transfer efficiency and high-quality result. The bell spins rapidly around its axis with a tangential velocity at the edge in the order of 100 m/s. The paint falls off the edge and enters the air with a large relative velocity, driving the atomization into small droplets where the resulting size distribution depends on the process conditions. Especially the rotation speed of the bell is an important parameter governing the size distribution. The main research question in this work is to investigate if the Taylor Analogy Breakup (TAB) model can be used to predict the resulting droplet size distributions in spray painting. As the paint is a viscous fluid a modification of the TAB model taking non-linear effects of large viscosity into account is proposed. The parameters in the breakup model are tuned by optimization to match droplet size distributions obtained in CFD simulations with measured ones. Results are presented for three cases with rotation speeds from 30 to 50 thousand RPM where the full droplet size distributions are compared with measurements. Good results are obtained for all three cases where the simulated size distributions compare well to measurements over a wide range of droplet sizes. The TAB method is able to quantitatively predict the result of the breakup process and can be used in a preprocessing stage of a full spray painting simulation, thereby reducing the need for costly and cumbersome measurements.
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| 4. |
- Andersson, Björn O, 1982, et al.
(författare)
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Modified TAB Model for Viscous Fluids applied to Breakup in Rotary Bell Spray Painting
- 2012
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Ingår i: ICLASS 2012 - 12th International Conference on Liquid Atomization and Spray Systems.
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Konferensbidrag (refereegranskat)abstract
- The Taylor Analogy Breakup (TAB) model is applied to droplet breakup in rotary bell spray painting commonly used in the automotive industry. The bell spins rapidly around its axis with a tangential velocity at the edge in the order of 100 m/s. The paint falls off the edge and enters the air with a large relative velocity, driving the atomization. The paint is a viscous fluid and a modification of the TAB model taking non-linear effects of large viscosity into account is described. The parameters in the breakup model are tuned to match droplet size distributions obtained in CFD simulations with measured ones. Results are presented for three cases with rotation speeds from 30 to 50 thousand RPM where the full droplet size distributions are compared with measurements. Good results are obtained for all three cases where the simulated size distributions compare well to measurements over a wide range of droplet sizes. The obtained results can be used in a preprocessing stage of a full spray painting simulation thereby reducing the need for costly and cumbersome measurements.
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| 5. |
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| 6. |
- Bergman, Miriam, 1978, et al.
(författare)
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CFD-Based Optimization of a Diesel-fueled Free Piston Engine Prototype for Conventional and HCCI Combustion
- 2008
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Ingår i: SAE International Journal of Engines. - : SAE International. - 1946-3944 .- 1946-3936. ; 1:1, s. 1118-1143
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results of a parametric CFD modeling study of a prototype Free Piston Engine (FPE), designed for application in a series hybrid electric vehicle. Since the piston motion is governed by Newton’s second law, accounting for the forces acting on the piston/translator, i.e. friction forces, electrical forces, and in-cylinder gas forces, having a high-level control system is vital. The control system changes the electrical force applied during the stroke, thus obtaining the desired compression ratio. Identical control algorithms were implemented in a MATLAB/SIMULINK model to those applied in the prototype engine. The ignition delay and heat release data used in the MATLAB/SIMULINK model are predicted by the KIVA-3V CFD code which incorporates detailed chemical kinetics (305 reactions among 70 species). Since the piston motion and frequency, the rate of heat release and the initial in-cylinder conditions all affect each other, while predicted using different modelling tools with no direct coupling between them, an iterative procedure was used among models describing:1. Piston dynamics governed by Newton’s second law including a high-level control system (using MATLAB/SIMULINK)2. Combustion processes (using KIVA-3V)3. Intake and exhaust system dynamics (using the GT-POWER module of the GT-SUITETM)Effects of varying parameters such as compression ratios, power supplied to the compressor, fuel injection timings and injection pressures have been studied in both conventional diesel and HCCI modes, the target being to identify optimal conditions for the combustion process in which the engine can be operated highly efficiently with very low-emissions.
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| 7. |
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| 8. |
- Bergman, Miriam, 1978, et al.
(författare)
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Chemical Mechanisms for Modelling HCCI with Gasoline and Diesel Oil Surrogates
- 2005
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Ingår i: Engine Combustion Processes. ; , s. 323-334
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Limited size chemical reaction mechanisms predicting ignition and combustion development of practical hydrocarbon fuels are necessary for multi-dimensional CFD modeling of the HCCI combustion mode in IC engines. In order to obtain accurate predictions within reasonable computational time, reduced mechanisms for gasoline and diesel oil surrogates have been constructed: 72 species, 313 reactions for diesel oil and 121 species, 614 reactions for gasoline. The mechanisms are based on sub-mechanisms developed for fuels constituent components, which are then reduced and optimized for engine applications. The optimization was performed using shock-tube and stirred reactor experimental data for individual components and the Chemkin-2 package software for computations and sensitivity analysis. The reduced mechanisms proved to be in a good agreement with the larger detailed mechanisms available in the literature as well as with relevant experimental data. Combined with the properties of liquid fuel, the diesel oil surrogate mechanism has been applied to reproduce spray ignition experiments in a constant volume vessel as well as for engine simulations, yielding a deeper understanding of the HCCI process.
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| 9. |
- Bergman, Miriam, 1978, et al.
(författare)
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Modification of a Diesel Oil Surrogate Model for 3D CFD Applied to Conventional and HCCI Combustion
- 2008
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Ingår i: SAE: Powertrains, Fuels and Lubricants Meeting; Rosemont, IL; United States; 6 October 2008 through 9 October 2008. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- This paper describes an analysis of the Diesel Oil Surrogate (DOS) model used at Chalmers University (Sweden), including 70 species participating in 310 reactions, and subsequent improvements prompted by the model’s systematic tendency to under-predict the combustion intensity in simulations of kinetically-driven combustion modes, e.g. Homogeneous Charged Compression Ignition (HCCI).Key bases of the model are the properties of a model Diesel fuel with the molecular formula C14H28. In the vapor phase, a global reaction decomposes the starting fuel, C14H28, into its constituent components; n-heptane (C7H16) and toluene (C7H8). This global reaction was modified to yield a higher n-heptane:toluene ratio, due to the importance of preserving an n-heptane-like cetane number. Three different (composite) versions of this global decomposition reaction were investigated separately and compared:1.3C14H28 + O2 => 4C7H16 + 2C7H8 +2H2O 2.2C14H28 => 3C7H16 + C7H8 3.3C14H28 + 3.5O2 => 5C7H16 + 0.5C7H8 + 3.5CO2 Reaction 1 is the original formulation and reactions 2 and 3 are novel alternatives. The effects of modifying the activation energies (E), collision frequency factors (A) and oxygen concentration exponents (AEO) of these reactions was examined when integrated into the 3D KIVA-3V CFD code, while leaving the elementary reactions unchanged. The results were compared with data obtained from measurements of a High Speed Direct Injected (HSDI) engine, operating in both conventional and HCCI combustion modes. Finally, the global reaction version and the rate constants giving the best agreement for the examined regimes were identified.
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| 10. |
- Bergman, Miriam, 1978, et al.
(författare)
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On Transient Temperature vs. Equivalence Ratio Emission Maps in Conjunction with 3D CFD Free Piston Engine Modeling
- 2007
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Ingår i: International Multidimensional Engine Modeling User’s Group Meeting at the SAE World Congress.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to acquire knowledge about temperature vs. equivalence ratio, conditions in which species are formed and destroyed during the combustion of diesel fuel, parametric maps were constructed for CO2, CO, OH, soot and soot precursors (C2H2) as well as for nitrogen oxides (NO and NO2). Each map was obtained by plotting data from a large number of simulations for various temperature vs. equivalence ratio combinations in a zero-dimensional, 0D, closed Perfectly Stirred Reactor, PSR. Since both the elapsed time and pressure change in an engine cycle, the maps were constructed according to engine pressure traces obtained from the Computational Fluid Dynamics, CFD, simulations. Since the pressure is changing in elapsed time intervals, the maps are called transient. Correlations between the maps and the 3D engine simulation results were then examined by plotting the temperature vs. equivalence ratio conditions in all computational cells of the CFD simulation on the maps. The map approach is a useful tool for visualizing the links between in-cylinder temperature vs. equivalence ratio conditions and emission levels, and to identify conditions that promote efficient, low-emission engine operation. All engine simulations were made for a free piston engine, but conclusions can be valid for conventional engines as well. The effect of varying spray model parameters such as the initial sauter mean radius, droplet size distribution and the constants in the break-up model was studied.
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