Load Limits with Fuel Effects of a Premixed Diesel Combustion Mode

2009 ◽  
Author(s):  
Andrew M. Ickes ◽  
Dennis N. Assanis ◽  
Stanislav V. Bohac
Keyword(s):  
Diesel Combustion ◽  
Combustion Mode ◽  
Fuel Effects ◽  
Load Limits

Fuel Effects on Diesel Combustion Processes

1996 ◽  
Author(s):  
E Clasen ◽  
K Song ◽  
S Campbell ◽  
K T. Rhee
Keyword(s):  
Diesel Combustion ◽  
Fuel Effects ◽  
Combustion Processes

Performance and emission characteristics of conventional diesel combustion/partially premixed charge compression ignition combustion mode switching of biodiesel-fueled engine

2019 ◽  
pp. 146808741986031
Author(s):  
Akhilendra Pratap Singh ◽  
Avinash Kumar Agarwal
Keyword(s):  
Aromatic Compounds ◽  
Electronic Control Unit ◽  
Mode Switching ◽  
Particulate Emissions ◽  
Exhaust Gas ◽  
Diesel Combustion ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Performance And Emission ◽  
Combustion Modes

In this experimental study, a production grade engine was modified to operate in two combustion modes, namely conventional diesel combustion (CDC) and premixed charge compression ignition (PCCI) combustion, depending on the engine load. For mode switching, an open electronic control unit was programmed to operate the engine in PCCI combustion mode up to medium engine loads and then automatically switching it to CDC mode at higher engine loads, by varying the fuel injection parameters and the exhaust gas recirculation rate. For performance and emission characterization in the entire load range (idling-to-full load) of the test engine, a test cycle of 300 s was used, which included CDC mode, PCCI combustion mode, and transition between these two modes. Results showed that both mineral diesel and B20 (20% biodiesel blended with mineral diesel, v/v) fueled PCCI combustion resulted in significantly lower NOx and particulate emissions compared to baseline CDC. Relatively lower exhaust gas temperature in PCCI combustion mode led to slightly inferior engine performance and higher concentration of unregulated emission species such as SO2, HCHO, and so on. B20-fueled engine resulted in relatively lower unregulated emission species and particulates compared to the mineral diesel–fueled engine in both the combustion modes. In CDC mode, contributions of accumulation mode particles were significantly higher compared to nucleation mode particles. Relatively lower emission of aromatic compounds in PCCI combustion mode compared to CDC mode was another important finding of this study; however, B20-fueled engines resulted in slightly higher emissions of aromatic compounds.

Mechanism of thermal efficiency improvement in twin shaped semi-premixed diesel combustion

2021 ◽  
pp. 146808742110264
Author(s):  
Kazuki Inaba ◽  
Yanhe Zhang ◽  
Yoshimitsu Kobashi ◽  
Gen Shibata ◽  
Hideyuki Ogawa
Keyword(s):  
Heat Release ◽  
Thermal Efficiency ◽  
Gas Flow ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Combustion Noise ◽  
Diesel Combustion ◽  
Combustion Mode ◽  
Secondary Stage ◽  
Combustion Phase

Improvements of the thermal efficiency in twin shaped semi-premixed diesel combustion mode with premixed combustion in the primary stage and spray diffusive combustion in the secondary stage with multi-stage fuel injection were investigated with experiments and 3D-CFD analysis. For a better understanding of the advantages of this combustion mode, the results were compared with conventional diesel combustion modes, mainly consisting of diffusive combustion. The semi-premixed mode has a higher thermal efficiency than the conventional mode at both the low and medium load conditions examined here. The heat release in the semi-premixed mode is more concentrated at the top dead center, resulting in a significant reduction in the exhaust loss. The increase in the cooling loss is suppressed to a level similar to the conventional mode. In the conventional mode the rate of heat release becomes more rapid and the combustion noise increases with advances in the combustion phase as the premixed combustion with pilot and pre injections and the diffusive combustion with the main combustion occurs simultaneously. In the semi-premixed mode, the premixed combustion with pilot and primary injections and the diffusive combustion with the secondary injection occurs separately in different phases, maintaining a gentler heat release with advances in the combustion phase. The mechanism of the cooling loss suppression with the semi-premixed mode at low load was investigated with 3D-CFD. In the semi-premixed mode, there is a reduction in the gas flow and quantity of the combustion gas near the piston wall due to the suppression of spray penetration and splitting of the injection, resulting in a smaller heat flux.

Effect of fuel cetane number on a premixed diesel combustion mode

2009 ◽  
Vol 10 (4) ◽  
pp. 251-263 ◽  
Author(s):  
A M Ickes ◽  
S V Bohac ◽  
D N Assanis
Keyword(s):  
Direct Injection ◽  
Cetane Number ◽  
Diesel Combustion ◽  
Gaseous Emissions ◽  
Combustion Mode ◽  
Small Deviations ◽  
Operating Range ◽  
Light Load ◽  
Gas Recirculation ◽  
Poor Stability

The ability of premixed low-temperature diesel combustion to deliver low particulate matter (PM) and NO x emissions is dependent on achieving optimal combustion phasing. Small deviations in combustion phasing can shift the combustion to less optimal modes, yielding increased emissions, increased noise, and poor stability. This paper demonstrates how variations in fuel cetane number affect the detailed combustion behaviour of a direct-injection, diesel-fuelled, premixed combustion mode. Testing was conducted under light load conditions on a modern single-cylinder engine, fuelled with a range of ultra-low sulphur fuels with cetane numbers ranging from 42 to 53. Fuel cetane number is found to affect ignition delay and, accordingly, combustion phasing. Gaseous emissions are a function of combustion phasing and exhaust gas recirculation (EGR) quantity, but are not directly tied to fuel cetane number. Fuel cetane number is merely one of many different engine parameters that shift combustion phasing. Furthermore, the operating range is constrained by the changes in cetane number: no injection timings yield acceptable combustion across the whole spread of tested cetane numbers. However, in terms of combustion phasing, the operating range is consistent, independent of fuel cetane number.

Flatness-Based Control of Mode Transitions Between Conventional and Premixed Charge Compression Ignition on a Modern Diesel Engine With Variable Valve Actuation

2013 ◽  
Author(s):  
Carrie M. Hall ◽  
Dan Van Alstine ◽  
Gregory M. Shaver
Keyword(s):  
Diesel Engine ◽  
Gas Exchange ◽  
Diesel Combustion ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Variable Valve Actuation ◽  
Advanced Combustion ◽  
Combustion Modes ◽  
Mode Transitions ◽  
Variable Valve

Energy needs in the transportation sector and strict emissions regulations have caused a growing focus on increasing engine efficiency while simultaneously minimizing engine out emissions. One method for accomplishing this is to leverage advanced combustion strategies which are efficient yet very clean. One such combustion mode is premixed charge compression ignition (PCCI). PCCI can lead to drastically lower emissions than conventional diesel combustion while still maintaining engine efficiencies; however, the engine operation region over which it can be utilized is limited. In order to take advantage of this advanced combustion mode, engines must be designed to move between conventional diesel combustion and PCCI. To achieve transitions between different combustion modes, a control strategy was developed which utilizes a extensively validated gas exchange model and flatness-based methods for trajectory planning and trajectory tracking to enable smooth transitions between different combustion modes on a modern diesel engine with variable valve actuation. Since the engine considered here has the ability to alter valve timings, the control method exploits both capabilities to control the gas exchange process as well as the effective compression ratio of the engine. Simulation results indicate that this flatness-based approach is effective in enabling mode transitions.

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