Emissions Optimization of Propane Dual Fuel Combustion Ignited by Diesel and Polyoxymethylene Dimethyl Ether At Low Loads PDF Download
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Author: Prabhat R Jha
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0
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Dual fuel engines utilize two different fuels consisting of a high reactivity fuel (HRF)injected into the cylinder and a low reactivity fuel (LRF), typically fumigated into the intakemanifold. In order to reduce the emissions of nitrogen oxides when compared against dieselcombustion, dual fuel engines begin the injection process early in the combustion cycle.However, at early injection timings dual fuel engines exhibit high emissions of both unburnedhydrocarbons (HC) and carbon monoxide (CO). This work discusses the emissions optimizationprocess to reduce emissions for two different fueling types, diesel-propane and poly-oxymethylene dimethyl ether (POMDME)-propane, on a single cylinder research engine (SCRE)based upon a PACCAR MX-11 heavy-duty engine while maintaining combustion and fuelconversion efficiencies.The parameters swept during this optimization process include start of injection, percentenergy substitution, a second injection and its timing, the split ratio - or the ratio of commandedduration of the first injection to that of the second, a coupled injection sweep, rail pressure, andintake pressure. These parameters were varied at a fixed gross indicated mean effective pressure(IMEPg) of 5 bar to represent low load operation as well as a fixed engine speed of 1339 rpm("B speed" of the SCRE). During all experiments a global limit of 1 g/kWh was set on theindicated specific NOx emissions, as well as a maximum pressure rise rate of 10 bar/deg, and acoefficient of variation of IMEPg at or below 5%. Using these limits and the emissions tradeoffsbetween HC, CO and NOx, this work was able to demonstrate diesel-propane emissionsimprovements of HC and CO of 86.4% and 66.8% respectively when compared to the baseline, while POMDME-propane emissions showed improvements in HC and CO of 90.9% and 86.2%respectively. Additionally, POMDME emissions demonstrated zero measurable filter smokenumber during all engine operations. A preliminary life cycle analysis of using both dual fuelcombinations have been compared against traditional diesel operation as well as battery poweredoperation and is found within the appendix of this work.
Author: Prabhat R Jha
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0
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Book Description
Dual fuel engines utilize two different fuels consisting of a high reactivity fuel (HRF)injected into the cylinder and a low reactivity fuel (LRF), typically fumigated into the intakemanifold. In order to reduce the emissions of nitrogen oxides when compared against dieselcombustion, dual fuel engines begin the injection process early in the combustion cycle.However, at early injection timings dual fuel engines exhibit high emissions of both unburnedhydrocarbons (HC) and carbon monoxide (CO). This work discusses the emissions optimizationprocess to reduce emissions for two different fueling types, diesel-propane and poly-oxymethylene dimethyl ether (POMDME)-propane, on a single cylinder research engine (SCRE)based upon a PACCAR MX-11 heavy-duty engine while maintaining combustion and fuelconversion efficiencies.The parameters swept during this optimization process include start of injection, percentenergy substitution, a second injection and its timing, the split ratio - or the ratio of commandedduration of the first injection to that of the second, a coupled injection sweep, rail pressure, andintake pressure. These parameters were varied at a fixed gross indicated mean effective pressure(IMEPg) of 5 bar to represent low load operation as well as a fixed engine speed of 1339 rpm("B speed" of the SCRE). During all experiments a global limit of 1 g/kWh was set on theindicated specific NOx emissions, as well as a maximum pressure rise rate of 10 bar/deg, and acoefficient of variation of IMEPg at or below 5%. Using these limits and the emissions tradeoffsbetween HC, CO and NOx, this work was able to demonstrate diesel-propane emissionsimprovements of HC and CO of 86.4% and 66.8% respectively when compared to the baseline, while POMDME-propane emissions showed improvements in HC and CO of 90.9% and 86.2%respectively. Additionally, POMDME emissions demonstrated zero measurable filter smokenumber during all engine operations. A preliminary life cycle analysis of using both dual fuelcombinations have been compared against traditional diesel operation as well as battery poweredoperation and is found within the appendix of this work.
Author: Mostafa Shameem Raihan
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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The objective of this thesis is to investigate and compare the performance and emissions characteristics of diesel-ignited methane and diesel-ignited propane dual fuel LTC in a single cylinder research engine (SCRE) at a constant engine load of 5.1 bar net indicated mean effective pressure (IMEP) and at a constant engine speed of 1500 RPM. Percentage of energy substitution of propane or methane (0 - 90 percent), diesel injection timing (SOI: 355 CAD -- 280 CAD), rail pressure (200 bar -- 1300 bar) and boost pressure (1.1 bar -- 1.8 bar) were varied to quantify their impact on engine performance and engine-out ISNOx, ISHC, ISCO, and smoke emissions. Advancing SOI to 310 CAD and beyond yielded simultaneous ISNOx and smoke emissions. A rail pressure of 500 bar was the optimal one for both fueling combinations while increasing boost pressure over 1.2 bar had a very little effect on ISNOx and smoke emissions.
Author: Chad Duane Carpenter
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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A 12.9 L heavy duty compression ignition engine was tested with strategies for dual fuel optimization. The effects of varied intake manifold pressure as well as split-injection strategies at a load of 5 bar BMEP and 85 PES were observed. These results were used to allow testing of split-injection strategies at a higher load of 10 bar BMEP at 70 PES that were void of MPRR above 2000 kPa/CAD. The split-injection strategies at 5 bar BMEP showed that lower BSNOx can be achieved with minimal drop in FCE. Varying intake manifold pressure revealed that combustion occurs earlier in a cycle with increasing intake manifold pressure and indirectly increasing FCE. A load of 10 bar BMEP at 70 PES should only use split-injection strategy to maintain load without high MPRR as efficiency drops with dependency on the second injection.
Author: Kyle Anthony Hodges
Publisher:
ISBN:
Category :
Languages : en
Pages : 142
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The present manuscript discusses the use of two diesel injections in diesel-ignited propane dual fuel Low Temperature Combustion (LTC). Using propane fumigation into the intake runners of a single cylinder research engine, the maximum and minimum percent energy substitution (PES) values were obtained to be 90% and 53%, respectively at 3.3 bar BMEP. An optimal PES value of 80% was used to explore the effects of a secondary injection on the engine-out emissions. The secondary injection proved to have a strong influence on combustion phasing (CA50). As combustion is phased closer to TDC the IFCE shows and increase of 4% at 5 bar BMEP and 6% at 3.3 bar BMEP. Finally, a relationship between the IFCE and the CO to CO2 conversion was developed. An increase in the carbon to hydrogen ratio of the fuel shows a reduction of the CO output of the engine while the CO2 concentration increases. More importantly however, the CO to CO2 conversion shows a direct effect on the IFCE. It is shown that a decrease in CO emissions found in the engine-out emissions will correlate directly with an increase in the IFCE.
Author:
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages :
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The goal of this study is to assess conventional and low temperature dual fuel combustion in light- and heavy-duty multi-cylinder compression ignition engines in terms of combustion characterization, performance, and emissions. First, a light-duty compression ignition engine is converted to a dual fuel engine and instrumented for in-cylinder pressure measurements. The primary fuels, methane and propane, are each introduced into the system by means of fumigation before the turbocharger, ensuring the air-fuel composition is well-mixed. Experiments are performed at 2.5, 5, 7.5, and 10 bar BMEP at an engine speed of 1800 RPM. Heat release analyses reveal that the ignition delay and subsequent combustion processes are dependent on the primary fuel type and concentration, pilot quantity, and loading condition. At low load, diesel-ignited propane yields longer ignition delay periods than diesel-ignited methane, while at high load the reactivity of propane is more pronounced, leading to shorter ignition delays. At high load (BMEP = 10 bar), the rapid heat release associated with diesel-ignited propane appears to occur even before pilot injection, possibly indicating auto-ignition of the propane-air mixture. Next, a modern, heavy-duty compression ignition engine is commissioned with an open architecture controller and instrumented for in-cylinder pressure measurements. Initial diesel-ignited propane dual fuel experiments (fumigated before the turbocharger) at 1500 RPM reveal that the maximum percent energy substitution (PES) of propane is limited to 86, 60, 33, and 25 percent at 5, 10, 15, and 20 bar BMEP, respectively. Fueling strategy, injection strategy, exhaust gas recirculation (EGR) rate, and intake boost pressure are varied in order to maximize the PES of propane at 10 bar BMEP, which increases from 60 PES to 80 PES of propane. Finally, diesel-ignited propane dual fuel low temperature combustion (LTC) is implemented using early injection timings (50 DBTDC) at 5 bar BMEP. A sweep of injection timings from 10 DBTDC to 50 DBTDC reveals the transition from conventional to low temperature dual fuel combustion, indicated by ultra-low NOx̳ and smoke emissions. Optimization of the dual fuel LTC concept yields less than 0.02 g/kW-hr NOx̳ and 0.06 FSN smoke at 93 PES of propane.
Author: Hongsheng Guo
Publisher: Frontiers Media SA
ISBN: 2889666212
Category : Technology & Engineering
Languages : en
Pages : 125
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Author: Prabhat Ranjan Jha
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 313
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It's crucial to use advanced combustion strategies to increase efficiency and decrease engine-out pollutants because of the compelling need to reduce the global carbon footprint. This dissertation proposes dual fuel low-temperature combustion as a viable strategy to decrease engine-out emissions and increase the thermal efficiency of future heavy-duty internal combustion (IC) engines. In dual fuel combustion, a low reactivity fuel (e.g. methane, propane) is ignited by a high reactivity fuel (diesel) in a compression-ignited engine. Generally, the energy fraction of low reactivity fuel is maintained at much higher levels than the energy fraction of the high reactivity fuel. For a properly calibrated engine, combustion occurs at lean and low-temperature conditions (LTC). This decreases the chances of the formation of soot and oxides of nitrogen within the engine. However, at low load conditions, this type of combustion results in high hydrocarbon and carbon monoxide emissions. The first part of this research experimentally examines the effect of methane (a natural gas surrogate) substitution on early injection dual fuel combustion at representative low loads of 3.3 and 5.0 bar BMEPs in a single-cylinder compression ignition engine (SCRE). Gaseous methane fumigated into the intake manifold at various methane energy fractions was ignited using a high-pressure diesel pilot injection at 310 CAD. Cyclic combustion variations at both loads were also analyzed to obtain further insights into the combustion process and identify opportunities to further improve fuel conversion efficiencies at low load operation. In the second part, the cyclic variations in dual fuel combustion of three different low reactivity fuels (methane, propane, and gasoline) ignited using a high-pressure diesel pilot injection was examined and the challenges and opportunities in utilizing methane, propane, and gasoline in diesel ignited dual fuel combustion, as well as strategies for mitigating cyclic variations, were explored. Finally, in the third part a CFD model was created for diesel methane dual fuel LTC. The validated model was used to investigate the effect of methane on diesel autoignition and various spray targeting strategies were explored to mitigate high hydrocarbon and carbon monoxide emissions at low load conditions.
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Category :
Languages : en
Pages :
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With increasingly restrictive NO x and particulate matter emissions standards, the recent discovery of new natural gas reserves, and the possibility of producing propane efficiently from biomass sources, dual fueling strategies have become more attractive. This paper presents experimental results from dual fuel operation of a four-cylinder turbocharged direct injection (DI) diesel engine with propane or methane (a natural gas surrogate) as the primary fuel and diesel as the ignition source. Experiments were performed with the stock engine control unit at a constant speed of 1800 rpm, and a wide range of brake mean effective pressures (BMEPs) (2.7-11.6 bars) and percent energy substitutions (PESs) of C 3 H 8 and CH 4. Brake thermal efficiencies (BTEs) and emissions (NO x, smoke, total hydrocarbons (THCs), CO, and CO 2) were measured. Maximum PES levels of about 80-95% with CH 4 and 40-92% with C 3 H 8 were achieved. Maximum PES was limited by poor combustion efficiencies and engine misfire at low loads for both C 3 H 8 and CH 4, and the onset of knock above 9 bar BMEP for C 3 H 8. While dual fuel BTEs were lower than straight diesel BTEs at low loads, they approached diesel BTE values at high loads. For dual fuel operation, NO x and smoke reductions (from diesel values) were as high as 66-68% and 97%, respectively, but CO and THC emissions were significantly higher with increasing PES at all engine loads.
Author: James S Harris
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0
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Internal combustion engines are a key aspect of society, and their continued use poses challenges from an environmental standpoint since they emit pollutant and greenhouse gas emissions. This dissertation focuses on experimental analysis of dual-fuel low temperature combustion (LTC), which can be used as a strategy to reduce engine-out emissions and increase engine efficiencies. Dual fuel LTC uses two different fuels, a high reactivity fuel (HRF) and a low reactivity fuel (LRF). The HRF has a higher cetane number than the LRF, which allows for easier auto-ignition in compression ignition engines. Dual fuel engines also utilize high air to fuel ratios to achieve LTC. This, combined with early injection timings of the HRF, helps to reduce oxides of nitrogen (NOx) emissions. At low load conditions, this is a problem since higher cycle-to-cycle variations can increase pollutants such as unburned hydrocarbons (UHC) and carbon monoxide (CO). To combat this, a firm understanding of dual fuel LTC is required, as well as a strategy for reducing the cycle-to-cycle variations. The first part of this work further identifies a combustion heat release 'transformation region' across different HRF injection timings wherein in-cylinder conditions arise that are conducive for ultra-low NOx emissions. This phenomenon occurs for different IC engine platforms and different fueling combinations. An experimental analysis, 0D chemical kinetic analysis, and 3D computation fluid dynamic (CFD) analysis were combined to elucidate the underlying causes for this phenomenon. The local stratification level of the fuel/air mixture was identified as the likely cause of combustion heat release transformation with changing HRF injection timing. The second part of the present work builds upon the findings of the first part by utilizing local stratification to mitigate cycle-to-cycle variations that are present at low loads. A framework of experiments was formulated for both a low engine load of 5 bar gross indicated mean effective pressure (IMEPg) and a high load of 15 bar IMEPg, wherein an injection strategy concept termed Spray TArgeted Reactivity Stratification (STARS) was utilized using both diesel and Polyoxymethelene-dimethyl-ether (POMDME) as HRFs. A steep decrease in UHC and CO emissions (> 80% reductions) as well as improved engine operation stability were demonstrated using both HRFs with dual fuel LTC at 5 bar IMEPg. Further, potential for emissions mitigation and efficiency improvement are discussed, as well as differences in the experimental results shown between the differing HRFs.
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Languages : en
Pages :
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Abstract : Among the various alternative fuels, natural gas is considered as a leading candidate for heavy-duty applications due to its availability and applicability in conventional internal combustion diesel engines. Compared to their diesel counterparts natural gas fueled spark-ignited engines have a lower power density, reduced low-end torque capability, limited altitude performance, and ammonia emissions downstream of the three-way catalyst. The dual fuel diesel/natural gas engine does not suffer with the performance limitations of the spark-ignited concept due to the flexibility of switching between different fueling modes. Considerable research has already been conducted to understand the combustion behavior of dual fuel diesel/natural gas engines. As reported by most researchers, the major difficulty with dual fuel operation is the challenge of providing high levels of natural gas substitution, especially at low and medium loads. In this study extensive experimental and simulation studies were conducted to understand the combustion behavior of a heavy-duty diesel engine when operated with compressed natural gas (CNG) in a dual fuel regime. In one of the experimental studies, conducted on a 13 liter heavy-duty six cylinder diesel engine with a compression ratio of 16.7:1, it was found that at part loads high levels of CNG substitution could be achieved along with very low NOx and PM emissions by applying reactivity controlled compression ignition (RCCI) combustion. When compared to the diesel-only baseline, a 75% reduction in both NOx and PM emissions was observed at a 5 bar BMEP load point along with comparable fuel consumption values. Further experimental studies conducted on the 13 liter heavy-duty six cylinder diesel engine have shown that RCCI combustion targeting low NOx emissions becomes progressively difficult to control as the load is increased at a given speed or the speed is reduced at a given load. To overcome these challenges a number of simulation studies were conducted to quantify the in-cylinder conditions that are needed at high loads and low to medium engine speeds to effectively control low NOx RCCI combustion. A number of design parameters were analyzed in this study including exhaust gas recirculation (EGR) rate, CNG substitution, injection strategy, fuel injection pressure, fuel spray angle and compression ratio. The study revealed that lowering the compression ratio was very effective in controlling low NOx RCCI combustion. By lowering the base compression ratio by 4 points, to 12.7:1, a low NOx RCCI combustion was achieved at both 12 bar and 20 bar BMEP load points. The NOx emissions were reduced by 75% at 12 bar BMEP while fuel consumption was improved by 5.5%. For the 20 BMEP case, a 2% improvement in fuel consumption was achieved with an 87.5% reduction in NOx emissions. At both load points low PM emissions were observed with RCCI combustion. A low NOx RCCI combustion system has multiple advantages over other combustion approaches, these include; significantly lower NOx and PM emission which allows a reduction in aftertreatment cost and packaging requirements along with application of higher CNG substitution rates resulting in reduced CO2 emissions.
