| 1. |
- Arunachalam, Prakash, et al.
(författare)
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Humid Air Motor : A Novel Concept to Decrease the Emissions Using the Exhaust Heat
- 2017
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2017-October
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Tidskriftsartikel (refereegranskat)abstract
- Humid air motor (HAM) is an engine operated with humidified inlet charge. System simulations study on HAM showed the waste heat recovery potential over a conventional system. An HAM setup was constructed, to comprehend the potential benefits in real-time, the HAM setup was built around a 13-litre six cylinder Volvo diesel engine. The HAM engine process is explained in detail in this paper. Emission analysis is also performed for all three modes of operation. The experiments were carried out at part load operating point of the engine to understand the effects of humidified charge on combustion, efficiency, and emissions. Experiments were conducted without EGR, with EGR, and with humidified inlet charge. These three modes of operation provided the potential benefits of each system. Exhaust heat was used for partial humidification process. Results show that HAM operation, without compromising on efficiency, reduces NOx and soot significantly over the engine operated without EGR. With HAM around 75-80% of the otherwise waste heat is recuperated (Appendix). This heat is used to reduce the pumping losses and emissions unlike in other waste heat recovery technologies, where the power production is the primary objective.
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| 2. |
- Belgiorno, Giacomo, et al.
(författare)
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Parametric Analysis of the Effect of Pilot Quantity, Combustion Phasing and EGR on Efficiencies of a Gasoline PPC Light-Duty Engine
- 2017
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2017-September:September
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a parametric analysis on the main engine calibration parameters applied on gasoline Partially Premixed Combustion (PPC) is performed. Theoretically, the PPC concept permits to improve both the engine efficiencies and the NOx-soot trade-off simultaneously compared to the conventional diesel combustion. This work is based on the design of experiments (DoE), statistical approach, and investigates on the engine calibration parameters that might affect the efficiencies and the emissions of a gasoline PPC. The full factorial DoE analysis based on three levels and three factors (33 factorial design) is performed at three engine operating conditions of the Worldwide harmonized Light vehicles Test Cycles (WLTC). The pilot quantity (Qpil), the crank angle position when 50% of the total heat is released (CA50), and the exhaust gas recirculation (EGR) factors are considered. The goal is to identify an engine calibration with high efficiency and low emissions. The experiments are conducted on a 2l Volvo Euro 6 diesel engine. The fuels tested are Gasoline RON75 and MK1 diesel. Gasoline RON75 permits operation from low to high engine load conditions. A pilot/main injection strategy is adopted, necessary to control the peak pressure rise rate (PRRmax) to acceptable values and to extend the maximum engine load operating area in PPC. The experimental results show that increasing the EGR rate from 0 to 30%, the net efficiency improves approximately of 1.5% units, due to the shorter combustion duration. For all the conditions examined in PPC, the soot levels are about two times lower than diesel combustion. With a high level of EGR, combined with optimized pilot quantity and combustion phasing, high-efficiency PPC combustion can be achieved without penalties in terms of NOx emissions compared to diesel combustion.
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| 3. |
- Björnsson, Ola, et al.
(författare)
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Evaluation of closed-loop combustion phase optimization for varying fuel compensation and cylinder balancing in a HD SI-ICE
- 2024
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Ingår i: SAE Technical Papers. - 0148-7191.
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Tidskriftsartikel (refereegranskat)abstract
- Alternative fuels, such as natural and bio-gas, are attractive options for reducing greenhouse gas emissions from combustion engines. However, the naturally occurring variation in gas composition poses a challenge and may significantly impact engine performance. The gas composition affects fundamental fuel properties such as flame propagation speed and heat release rate. Deviations from the gas composition for which the engine was calibrated result in changes in the combustion phase, reducing engine efficiency and increasing fuel consumption and emissions. However, the efficiency loss can be limited by estimating the combustion phase and adapting the spark timing, which could be implemented favorably using a closed-loop control approach. In this paper, we evaluate the efficiency loss resulting from varying gas compositions and the benefits of using a closed-loop controller to adapt the spark timing to retain the nominal combustion phase. We use a 13-liter natural gas-fueled heavy-duty (HD) spark-ignited (SI) internal combustion engine (ICE) provided by Volvo. We define the combustion phase by peak pressure location (PPL) estimations based on ion current measurements, which is an affordable, low-maintenance, and robust alternative to in-cylinder pressure sensors for PPL estimation. We perform cylinder-individual closed-loop control of the spark timing, which compensates for variations in fuel properties affecting all cylinders and achieves cylinder balancing. Applying the proposed PPL estimation and closed-loop ignition timing control significantly improves engine performance and reduces fuel consumption and emissions.
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| 4. |
- Denny, Michael, et al.
(författare)
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Optical Investigation on the Combustion Process Differences between Double-Pilot and Closely-Coupled Triple-Pilot Injection Strategies in a LD Diesel Engine
- 2019
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Ingår i: International Powertrains, Fuels & Lubricants Meeting. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019-January
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Konferensbidrag (refereegranskat)abstract
- The combustion processes of three injection strategies in a light-duty (LD) diesel engine at a medium load point are captured with a high speed video camera. A double-pilot/main/single-post injection strategy representative of a LD Euro 6 calibration is considered as the reference. There is a modest temporal spacing (dwell) after the first pilot (P1) and second pilot (P2). A second strategy, "A," adds a third pilot (P3). The dwell after both P2 and P3 are several times shorter than in the reference strategy. A third strategy, "B," further reduces all dwells. Each injection has its own associated local peak in the heat release rate (HRR) following some ignition delay. Between these peaks lie local minima, or dips. In all three cases, the fuel from P1 combusts as a propagating premixed flame. For all strategies, the ignition of P2 primarily occurs at its interface with the existing combustion regions. Extinguishing of the prevailing combustion by the fuel jets of later injections is noted in all strategies. This phenomenon is confirmed by comparing the timing of each fuel injection with the dips in the HRR and spatial luminescence over time. These dips after each injection are larger than would be expected by the cooling effect of the injected fuel alone. Furthermore, not all dips in the HRR are the result of this extinguishing, and it would not have been possible to determine if the dips are due to this extinguishing or a simple exhaustion of available fuel without this optical investigation. Even if the precise hydraulic injection timing can be known, knowledge of the spatial relationship of the injected fuel and prevailing combustion is necessary.
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| 5. |
- Dimitrakopoulos, Nikolaos, et al.
(författare)
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PPC operation with low ron gasoline fuel. A study on load range on a euro 6 light duty diesel engine
- 2017
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Ingår i: COMODIA 2017 - 9th International Conference on Modeling and Diagnostics for Advanved Engine Systems.
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Konferensbidrag (refereegranskat)abstract
- Gasoline Partially Premixed Combustion (PPC) is a promising alternative combustion concept that can offer both high indicated efficiency and low exhaust emissions in terms of NOx and soot, compared to conventional diesel combustion (CDC). Previous research has shown that PPC can operate with gasoline-like fuels of varying RON numbers. Some of the most promising results come with the use of gasoline of low octane number, around RON 70. In this study, a commercially available; 2 litre Euro 6 light duty diesel engine is being operated under various load and speed conditions with the use of RON 75 gasoline. The aim is to evaluate the ability of the engine to operate under PPC conditions with the use of as much OEM hardware installed as possible, in this case a double stage turbocharger. High amount of EGR, approximately 30%, is used in order to control NOx production and combustion reaction rates, together with a double injection strategy, which is beneficial at controlling the pressure rise rate and enable high load operation. The engine is operated at three different RPM levels, 1200-1800-2400 and between 2 to 16 bar IMEPg. Results show that combustion instability poses the limit at the low load while low oxygen content restricts the high load operation. Due to the premixed type of combustion, a fast combustion event is possible, giving a higher effective expansion ratio, which improves the indicated efficiency to levels higher than CDC, while indicated emissions are comparable to CDC operation.
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| 6. |
- Fang, Cheng, et al.
(författare)
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Closed-loop combustion phase control for multiple combustion modes by multiple injections in a compression ignition engine fueled by gasoline-diesel mixture
- 2018
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619. ; 231, s. 816-825
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Tidskriftsartikel (refereegranskat)abstract
- Partially premixed combustion with low octane fuel aims to reduce NOx and soot emission simultaneously without fuel consumption penalty. Cylinder pressure based combustion phase control is an essential technology for partially premixed combustion. A novel closed-loop combustion phase control strategy for multiple combustion modes is proposed in the current study. The combustion modes are classified into three basic categories based on injection patterns and heat release stages: (1) with only one heat release stage; (2) with two separated heat release stages; (3) with two overlapped heat release stages. Crank angle when 50% fuel is consumed (CA50) is chosen as the combustion phase indicator for the first case. Start of combustion (SOC) of each heat release stage is the combustion phase indicator for the second case. Both SOC and CA50 are the combustion phase indicators for the third case. Each combustion phase is closed-loop controlled by a proportional–integral (PI) controller with the timing adjustments of the corresponding injection. The control strategy is verified under different operating conditions in a 1.9 L light duty diesel engine fueled by gasoline-diesel mixture (volumetric 70% gasoline, 30% diesel). The experimental results show that the control strategy is able to control the combustion phase, reduce cylinder to cylinder variations as well as cycle to cycle variations under the operating conditions with exhaust gas circulation (EGR) rates of 10% and 15%.
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| 7. |
- Fang, Cheng, et al.
(författare)
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Start of low temperature reactions detection based on motoring pressure prediction for partially premixed combustion
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 141, s. 1101-1109
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Tidskriftsartikel (refereegranskat)abstract
- Partially premixed combustion aims to reduce NOx and particulate matter emission without fuel consumption penalty. Low temperature reactions are important for the partially premixed combustion. In the current study, a self-adaptive strategy is introduced to predict the motoring pressure by means of an equivalent isentropic index. The start of the low temperature reactions is detected when the pressure difference between the measured pressure and the predicted pressure is higher than a threshold value. Experimental results show that the maximum variation between the measured and the predicted motoring pressure before the top dead center is less than 0.02 bar. It is also demonstrated that the presented detection method is able to detect the start of the low temperature reactions under different engine operating conditions with varying injection timing, injection duration, number of injections and exhaust gas recirculation rate.
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| 8. |
- Fang, Cheng, et al.
(författare)
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Study on low temperature heat release of partially premixed combustion in a heavy duty engine for real-time applications
- 2019
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 148, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- Partially premixed combustion aims to reduce NOx and particulate matter emission without fuel consumption penalty. Low temperature heat release (LTHR) is an important process to be investigated. A novel motoring pressure prediction algorithm based on variable polytropic exponents was introduced and utilized to estimate average heat transfer coefficient as well as heat dissipation for real-time applications. A series of parameters, such as start of combustion (SOC) of LTHR, crank angle of 50% heat released (CA50) during LTHR, duration of LTHR and heat amount of LTHR, were further analyzed under different engine operation conditions. The results demonstrated that: (1) the absolute motoring pressure prediction error was below 0.5 bar with a relative error below 4%; (2) the average heat released during LTHR was about 40–65 J, and the mass burned was about 1–3% of the total mass burned; (3) CA50 of LTHR was more stable than SOC of LTHR, and was a better indicator for real-time combustion phase control; (4) similar combustion phase and heat amount of LTHR could be reached by adjusting the timing of the third injection regardless the difference in timing of the second injection; (5) the combustion phase and heat amount of LTHR could be controlled by the duration of the second injection.
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| 9. |
- García, Antonio, et al.
(författare)
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Combining in-cylinder pressure and 1D simulation tools to understand the combustion characteristics of natural gas in pre-chamber ignition systems for energy generation
- 2021
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 240
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Tidskriftsartikel (refereegranskat)abstract
- Recent outlooks suggest a long-term relevance of internal combustion engines for both power generation and transportation. Nonetheless, stringent pollutant reduction requirements combined with new CO2 mandates draws a challenging scenario, requiring intensive research and development activities to develop and optimize combustion modes to fulfill these requirements. Among the recent advancements, the active pre-chamber ignition system has been considered as a potential alternative to achieve a highly efficient and clean combustion process. Its combustion development is dictated by the pre-chamber ignition system which will provides a high energy flow jet inside the main chamber to enable a multi-site oxidation of the global lean mixture. The comprehension and quantification of the flow and combustion characteristics of the pre-chamber are of utmost importance to optimize the engine operation and pre-chamber design. Nonetheless, restrictive space for instrumentation at experimental side requires alternative numerical methods to aid the quantification of the state parameters and combustion process of these systems. In this sense, this research proposes a novel methodology combining in-cylinder pressure measurement and 1-D simulations as a tool to determine the state, flow and combustion development of different active pre-chambers operating with natural gas in a heavy-duty engine for power generation. The methodology is developed considering 3 different pre-chamber geometries, operating at different spark timings and equivalence ratios. The results suggest that the methodology is able to quantify the state conditions prior to the spark discharge as well as the evolution of the combustion process by means of considering the perturbations of the mass flow from the pre-chamber inside the main chamber energy balance. Moreover, the methodology allowed to quantify variations of equivalence ratio as small as 0.1 and combustion durations variations of 1 CAD.
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| 10. |
- Jorques Moreno, Carlos, et al.
(författare)
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Cylinder Pressure Based Virtual Sensor for In-Cycle Pilot Mass Estimation
- 2018
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Ingår i: SAE International Journal of Engines. - : SAE International. - 1946-3944. ; 11:6, s. 1167-1182
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a virtual sensor for the estimation of the injected pilot mass in-cycle is proposed. The method provides an early estimation of the pilot mass before its combustion is finished. Furthermore, the virtual sensor can also estimate pilot masses when its combustion is incomplete. The pilot mass estimation is conducted by comparing the calculated heat release from in-cylinder pressure measurements to a model of the vaporization delay, ignition delay and the combustion dynamics. A new statistical approach is proposed for the detection of the start of vaporization and the start of combustion. The discrete estimations, obtained at the start of vaporization and the start of combustion, are optimally combined and integrated in a Kalman Filter that estimates the pilot mass during the vaporization and combustion. The virtual sensor was programmed in a Field Programmable Gate Array (FPGA), and its performance tested in a Scania D13 Diesel engine. The experimental results showed that the method can effectively improve the in-cycle pilot mass estimation. The accuracy, quantified by the average error between the actual injected mass and the estimated mass, was improved from an induced initial bias error of ±3 mg/st to a final error of ±0.1 mg/st, with a precision of ±0.45 mg/st. A level of precision of ±0.5 mg/st was already obtained at the peak of the pilot heat release. The suggested method is robust against changing operating conditions based on the calibration points. With the proposed parametrization, this is limited to regions where the parameter dependence is linear. The maximum calibration bias error for points out of the calibration range was within ±0.5 mg/st, with a precision of ±0.8 mg/st. In addition, the method was found to be robust against most input measurement errors and parameter bias. The major error sensitivity was detected for TDC offset. Different fuels than those used for calibration were found to result in an error proportional to the lower heating value error. The estimation framework can easily integrate more complex models to allow the estimation of greater pilot masses and multiple injections. The pilot mass estimation can be used to predict the pilot combustion and its effect on the main injection. This allows for better in-cycle controllability i.e. ability to adjust the main injection timing and duration, cycle-to-cycle control and adaptation of pilot and main injections. The closed-loop control of the combustion enables improved engine performance and efficiency, and reduced emissions variability.
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