Hydrogen-Enriched Biogas Premixed Charge Combustion and Emissions in DI and IDI Diesel Dual Fueled Engines: A Comparative Study

2021 ◽  
pp. 1-27
Author(s):  
Van Ga Bui ◽  
Thi Minh Tu Bui ◽  
Anh Tuan Hoang ◽  
Sandro Nizetic ◽  
Thanh Xuan Nguyen Thi ◽  
...  

Abstract The paper presents a comparative study on combustion and emissions of hydrogen-enriched biogas premixed charge in direct injection dual fuel (DIDF) engine and indirect injection dual fuel (IDIDF) engine. The results show that the IDIDF engine outperforms the DIDF engine in terms of higher indicative engine cycle work (Wi), lower emissions of CO, soot, and noise, but the disadvantage is higher NOx emission. Under the same fueling condition, the IDIDF engine's Wi is on average 6% higher than that of the DIDF engine, but the NOx concentration in the combustion products of the IDIDF engine is 1.5 times higher than that of the DIDF engine. The IDIDF engine creates the stratified mixture distribution with higher O2 concentration in the auxiliary combustion chamber, which is favorable for auto ignition and reduces the ignition delay. The biogas composition affects slightly CO, and soot emissions, but significantly affects NOx emission. When the methane composition in biogas increases from 60% to 80%, the soot volume fraction is approximately 0.1ppm in both types of combustion chambers; the CO concentration varies from 1.4-1.8%, meanwhile, the NOx concentration varies from 3000-5000ppm in the case of IDIDF engine and 2500-4500ppm in the case of DIDF engine. For both types of dual fuel engines, when engine speed increases, CO concentration, and the soot volume fraction increase, while Wi and NOx concentration decrease.

2019 ◽  
Vol 8 (2) ◽  
pp. 5013-5016

The present study focuses on incorporation of alternative fuels along with existing internal combustion engines (ICE) without making major modifications. Acetylene has good combustion qualities with auto ignition temperature of 3050C. To increase the use of acetylene as non-petroleum gas in ICE, we carried experimentation on a single cylinder constant speed diesel engine. In this study, direct injection (DI) and constant speed compression ignition (CI) engine tested with pure diesel and diesel-acetylene dual fuel mode. We conducted experiments to study the performance characteristics of DI diesel engine in dual fuel mode by aspirating acetylene gas in the inlet manifold with a flow rate of 2 liters/minute (lpm) of acetylene. Observation recorded that, during idling condition to get the same power output when aspirated with the 2 lpm acetylene, 3.5% less amount of diesel required. For maximum load 9% less amount of diesel required. And 12% less amount of diesel required during partial loading condition. Also, the performance shows increased trend in indicated power and brake power by 1-2%. It was also observed that use of acetylene gas has more influence on emission of CO2. Emission results showed that without a catalytic convertor, 8% decreased amount of CO2 released during idling condition. Similar emission results of engine found during full load condition when acetylene used along with diesel, supporting the health of environment for reduction of global warming.


2021 ◽  
Author(s):  
Shouvik Dev ◽  
David Stevenson ◽  
Amin Yousefi ◽  
Hongsheng Guo ◽  
James Butler

Abstract Diesel fueled generators are widely used for power generation in remote and/or off-grid communities. In such communities, local organic waste streams can be used to generate biogas which can be used to replace diesel used by diesel generators to lower fuel cost and reduce greenhouse gas (GHG) emissions. Diesel powered generators can be easily retrofitted with a biogas dosing line in the engine intake to introduce biogas, but appropriate optimization would be of great help to further improve generator performance and reduce GHG emissions. The objective of this research is to demonstrate simplified optimization methods that can reduce GHG emissions (carbon dioxide and methane) from such retrofitted dual-fuel engines under various biogas compositions. The study was conducted on a modern 30 kilowatt (kW) generator using an electronically controlled, four-stroke, four-cylinder, direct injection, turbo-charged diesel engine. The engine was operated with the factory electronic control unit (ECU) and a programmable ECU which allowed for control of the fuel injections and exhaust gas recirculation (EGR) valve. Biogas was simulated by using natural gas (with more than 95% methane by volume) which was diluted with either carbon dioxide or nitrogen. This study consisted of two areas. The first one was the comparison of the engine performance when operating with biogas using the factory ECU and the programmable ECU with user optimized fuel injection. The second one was the influence of volume fraction of carbon dioxide or nitrogen in the biogas. The test results reinforced the importance of optimizing the diesel injections when the engine was operated in the biogas-diesel dual-fuel mode to ensure complete combustion and achieve a reduction in GHG emissions. Increasing nitrogen fraction had a minimal effect on the emissions, but increasing carbon dioxide fraction caused the NOx and methane emissions to decrease, and the indicated thermal efficiency to increase.


2020 ◽  
Vol 10 (10) ◽  
pp. 3416
Author(s):  
Bui Van Ga ◽  
Pham Quoc Thai

Combustion characteristics and harmful emissions with emphasized soot emission in the new concept of a biogas-dimethyl ether (DME) hybrid dual-fuel engine were analyzed. The effects of DME content, biogas compositions and diesel injection were examined. At any biogas composition, a rise in DME content in the fuel mixture leads to an increase in indicative engine cycle work (Wi) and NOx but a decrease in CO and soot volume fraction (fv). The effects of DME on Wi and soot volume fraction are more significant for poor biogas than for rich biogas, contrary to its effect tendency on CO and NOx concentrations. With a given operating condition and DME content, the biogas compositions slightly affect the performance and emission of a biogas-DME hybrid dual-fuel engine. At a fixed global equivalence ratio, the reduction of diesel injection leads to an increase in Wi and NOx concentration but a decrease in CO and soot volume fraction. The lower the diesel injection is, the more significant the effects of DME content on the combustion properties and pollutant emissions are. At a given operating condition and the same global equivalence ratio, the biogas-DME PCCI combustion mode is more advantageous than biogas-DME dual-fuel combustion mode. The substitution of diesel pilot ignition by DME pilot ignition in a biogas-DME hybrid dual engine is the optimal solution for both performance improvement and pollution emissions reduction.


Author(s):  
Mahdiar Khosravi ◽  
Jeremy Rochussen ◽  
Jeff Yeo ◽  
Patrick Kirchen ◽  
Gordon McTaggart-Cowan ◽  
...  

Its inherent economic and environmental advantages as an internal combustion engine fuel make natural gas (NG) an attractive alternative to diesel fuel as the primary energy source for some compression ignition (CI) engine applications. Diesel pilot-ignition of NG is an attractive fueling strategy as it typically requires minimal modification of existing CI engines. Furthermore, this strategy makes use of the highly developed direct injection (DI) diesel fuel systems already employed on modern CI engines for to control dual-fuel (DF) combustion. Despite the increasing popularity of the dual-fuel NG engine concept, the fundamental understanding of the fuel conversion mechanisms and the impact of the fueling parameters is still incomplete. A conceptual understanding of the relevant physics is necessary for further development of fueling and pilot-ignition strategies to address the shortcomings of dual-fuel combustion, such as low-load emissions and combustion stability. An experimental facility supporting optical diagnostics via a Bowditch piston arrangement in a 2-litre, single-cylinder research engine (Ricardo Proteus) was used in this study to consider the effect of fueling parameters on the fuel conversion process in a dual fuel engine. Fueling was achieved with port injected CH4 and diesel direct injection using a common rail system. Simultaneous, high-speed natural luminosity (NL) and OH* chemiluminescence imaging was used to characterize dual-fuel combustion and the influence of pilot injection pressure (300 bar vs. 1300 bar) and relative diesel-CH4 ratios (pilot ratio, PR), as these have been noted as key operating dual-fuel control metrics. The pilot injection pressure was observed to have a significant impact on the fuel conversion process. At higher pilot injection pressures, the auto-ignition sites were concentrated around the piston bowl periphery and the reaction zone propagated towards the center of the bowl. At lower pilot injection pressures, ignition initiated in the vicinity of the pilot fuel jet structures and resulted in a more heterogeneous fuel conversion process with regions of intense natural luminosity, attributed to particulate matter. An increase in the pilot ratio (i.e., increased diesel fraction) resulted in a more aggressive combustion event, due to a larger fraction of energy released in a premixed auto-ignition event. This was coupled with a decrease in the fraction of the combustion chamber with significant OH* or NL light emission, indicating incomplete fuel conversion in these regions. The insight to the dual-fuel conversion processes presented in this work will be ultimately used to develop dual-fuel injection strategies, as well as provide much needed validation data for modeling efforts.


2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. C. Polk ◽  
C. M. Gibson ◽  
N. T. Shoemaker ◽  
K. K. Srinivasan ◽  
S. R. Krishnan

Dual fuel engine combustion utilizes a high-cetane fuel to initiate combustion of a low-cetane fuel. The performance and emissions benefits (low NOx and soot emissions) of dual fuel combustion are well-known. Ignition delay (ID) of the injected high-cetane fuel plays a critical role in quality of the dual fuel combustion process. This paper presents experimental analyses of the ID behavior for diesel-ignited propane and diesel-ignited methane dual fuel combustion. Two sets of experiments were performed at a constant engine speed (1800 rev/min) using a four-cylinder direct injection diesel engine with the stock electronic conversion unit (ECU) and a wastegated turbocharger. First, the effects of fuel–air equivalence ratios (Фpilot ∼ 0.2–0.6 and Фoverall ∼ 0.2–0.9) on IDs were quantified. Second, the effects of gaseous fuel percent energy substitution (PES) and brake mean effective pressure (BMEP) (from 2.5 to 10 bars) on IDs were investigated. With constant Фpilot (>0.5), increasing Фoverall with propane initially decreased ID but eventually led to premature propane auto-ignition; however, the corresponding effects with methane were relatively minor. Cyclic variations in the start of combustion (SOC) increased with increasing Фoverall (at constant Фpilot) more significantly for propane than for methane. With increasing PES at constant BMEP, the ID showed a nonlinear trend (initially increasing and later decreasing) at low BMEPs for propane but a linearly decreasing trend at high BMEPs. For methane, increasing PES only increased IDs at all BMEPs. At low BMEPs, increasing PES led to significantly higher cyclic SOC variations and SOC advancement for both propane and methane. Finally, the engine ignition delay (EID), defined as the separation between the start of injection (SOI) and the location of 50% of the cumulative heat release, was also shown to be a useful metric to understand the influence of ID on dual fuel combustion. Dual fuel ID is profoundly affected by the overall equivalence ratio, pilot fuel quantity, BMEP, and PES. At high equivalence ratios, IDs can be quite short, and beyond a certain limit, can lead to premature auto-igniton of the low-cetane fuel (especially for a reactive fuel like propane). Therefore, it is important to quantify dual fuel ID behavior over a range of engine operating conditions.


Author(s):  
Xiao Ma ◽  
Yue Ma ◽  
Liang Zheng ◽  
Yanfei Li ◽  
Zhi Wang ◽  
...  

An approach based on regression was developed to reveal the soot volume fraction (SVF) distribution of a horizontal cross-section in an optically accessible gasoline direct injection engine, based on the quantitative data in vertical images from planar laser-induced incandescence, which was calibrated by the laser extinction method (LEM). The approach used the matching of the corresponding pixels in the vertical and the horizontal images to solve the problem of visible range that limited the use of the LEM in measuring SVFs of the horizontal plane. Local SVFs of as low as 0.05 ppm can be detected. Analysis of both the horizontal and vertical image results showed that the case of ϕa = 0.7 (equivalent air–fuel ratio) resulted in significantly rich soot regions with a peak SVF approximately three times higher than that of the case with ϕa = 0.8.


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