Browsing by Author "Gainey, Brian"

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    Catalytic partial oxidation reformation of diesel, gasoline, and natural gas for use in low temperature combustion engines
    (Elsevier, 2019) Hariharan, Deivanayagam; Yang, Ruinan; Zhou, Yingcong; Gainey, Brian; Mamalis, Sotirios; Smith, Robyn E.; Lugo-Pimentel, Michael A.; Castaldi, Marco J.; Gill, Rajinder; Davis, Andrew; Modroukas, Dean; Lawler, Benjamin; State University of New York (SUNY) System; State University of New York (SUNY) Stony Brook; City University of New York (CUNY) System; City College of New York (CUNY); University of Alabama Tuscaloosa
    Onboard reforming has relevance to both conventional and advanced combustion concepts. Most recently, onboard reforming has been proposed to enable "Single-Fuel RCCI" combustion and therefore, this paper explores catalytic partial oxidation reforming of three potential transportation-relevant fuels: gasoline, diesel, and natural gas. Reformation is performed at two pressure levels (between 15 and 60 psig) for each parent fuel for equivalence ratios ranging from 3.7 to 7.6 and the gaseous reformate mixtures are characterized with gas chromatography. The percentage of diesel oxidized during reformation is similar across all of the equivalence ratios. However, the percentage of gasoline and natural gas oxidized during reformation decreased with increasing equivalence ratio. The energy released during the reformation process is also calculated and presented for each gaseous reformate fuel. The lower heating value of every reformate fuel is lower than 20% of their respective parent fuel, due to the high concentration of inert gases (mostly nitrogen) in the reformate fuel mixtures. Two reformed fuels for each parent fuel were then selected to study their autoignition characteristics using HCCI combustion on a Co-operative Fuel Research (CFR) engine. The equivalence ratio is maintained at 0.31 and the combustion phasing was held constant by varying the intake temperature. Although the equivalence ratio is constant, the input energy from the different reformate fuels is not constant due to the component concentrations in the fuel. The gaseous reformate fuels are then compared to gasoline, natural gas, and the primary reference fuels in HCCI to determine an effective Primary Reference Fuel (PRF) number or effective octane rating for each gaseous reformate fuel. The effective octane rating for the gaseous reformate fuels fell slightly above the PRF number scale at an effective octane number of -110.
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    A comprehensive experimental investigation of low-temperature combustion with thick thermal barrier coatings
    (Pergamon, 2021) Yan, Ziming; Gainey, Brian; Gohn, James; Hariharan, Deivanayagam; Saputo, John; Schmidt, Carl; Caliari, Felipe; Sampath, Sanjay; Lawler, Benjamin; Clemson University; University of Alabama Tuscaloosa; State University of New York (SUNY) System; State University of New York (SUNY) Stony Brook
    Thick thermal barrier coatings (TBCs) have a significant potential to increase thermal efficiency by reducing heat transfer losses. However, in conventional combustion modes, the drawbacks associated with charge heating and higher propensity to knock have outweighed the efficiency benefits. Since the advanced low-temperature combustion (LTC) concepts are fundamentally different from the conventional combustion modes, these penalties do not exist in most of LTCs. The current experimental study shows the feasibility and benefits of thick TBCs with advanced LTC enabled by two different fuels: conventional gasoline and wet ethanol 80 (WE80, i.e., 80% ethanol and 20% water by mass). A total of five pistons were tested, including two metal baselines and three TBCcoated pistons with different thicknesses or surface finishes. A load sweep was conducted with each fuel on each piston within the same constraints. The thick TBCs extends the low load limit by about 15% for both gasoline and WE80 cases. A deterioration of the high load limit was not observed, which implies that the charge heating penalty does not occur in LTCs. The combustion efficiency increased for the thicker TBC by up to 2% points, and the fuel conversion efficiency was increased by up to 4.3%. The gasoline cases experience the largest benefits at low load, while the wet ethanol experiences the largest benefits at mid-to-high load. The intake temperature requirement is successfully reduced by 10-15 K. It is also observed that the dense sealing layer results in a significant improvement to UHC emissions. All of the coated pistons survived the 10-20 h of engine operation with no visual failure. (c) 2021 Elsevier Ltd. All rights reserved.
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    The Effects of Thick Thermal Barrier Coatings on Low-Temperature Combustion
    (2020) Yan, Ziming; Gainey, Brian; Gohn, James; Hariharan, Deivanayagam; Saputo, John; Schmidt, Carl; Caliari, Felipe; Sampath, Sanjay; Lawler, Benjamin; University of Alabama Tuscaloosa
    An experimental study was conducted on a Ricardo Hydra single-cylinder light-duty diesel research engine. Start of Injection (SOI) timing sweeps from -350 deg aTDC to -210 deg aTDC were performed on a total number of five pistons including two baseline metal pistons and three coated pistons to investigate the effects of thick thermal barrier coatings (TBCs) on the efficiency and emissions of low-temperature combustion (LTC). A fuel with a high latent heat of vaporization, wet ethanol, was chosen to eliminate the undesired effects of thick TBCs on volumetric efficiency. Additionally, the higher surface temperatures of the TBCs can be used to help vaporize the high heat of vaporization fuel and avoid excessive wall wetting. A specialized injector with a 60° included angle was used to target the fuel spray at the surface of the coated piston. Throughout the experiments, the equivalence ratio, ϕ, was maintained constant at 0.4; the combustion phasing was consistently matched at 6.8 ± 0.4 deg aTDC. It can be concluded that the thick TBC cases achieved 1 to 2 percentage points improvement in combustion efficiency, and generally, a ~2 percentage points increase in indicated engine efficiency. It is also noticed that applying a dense top sealing layer to the TBC further improves the UHC emissions compared to the TBC coated piston with an unsealed surface. From the heat release analysis, it can be concluded that the TBCs have no significant impact on the heat release process and knock intensity while matching the combustion phasing; however, it reduces the intake temperature requirement by up to 20 K. The exhaust gas temperatures were expected to increase for the TBC cases, but the expected increase in exhaust temperature was not conclusive from the results observed in this study.
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    Experimental Study of the Effect of Start of Injection and Blend Ratio on Single Fuel Reformate RCCI
    (ASME, 2020) Hariharan, Deivanayagam; Gainey, Brian; Yan, Ziming; Mamalis, Sotirios; Lawler, Benjamin; University of Alabama Tuscaloosa; Clemson University; State University of New York (SUNY) System; State University of New York (SUNY) Stony Brook
    A new concept of single fuel reactivity-controlled compression ignition (RCCI) has been proposed through the catalytic partial oxidation (CPOX) reformation of diesel fuel. The reformed fuel mixture is then used as the low reactivity fuel and diesel itself is used as the high reactivity fuel. In this paper, two reformate mixtures from the reformation of diesel were selected for further analysis. Each reformate fuel mixture contained a significant fraction of inert gases (89% and 81%). The effects of the difference in the molar concentrations of the reformate mixtures were studied by experimenting with diesel as the direct injected fuel in RCCI over a varying start of injection timings and different blend ratios (i.e., the fraction of low and high reactivity fuels). The reformate mixture with the lower inert gas concentration had earlier combustion phasing and shorter combustion duration at any given diesel start of injection timing. The higher reactivity separation between reformate mixture and diesel, compared with gasoline and diesel, causes the combustion phasing of reformate-diesel RCCI to be more sensitive to the start of injection timing. The maximum combustion efficiency was found at a CA50 before top dead center (TDC), whereas the maximum thermal efficiency occurs at a CA50 after TDC. The range of energy-based blend ratios in which reformate-diesel RCCI is possible is between 25% and 45%, limited by ringing intensity (RI) at the low limit of blend ratios, and coefficient of variance (COV) of net indicated mean effective pressure (IMEPn) and combustion efficiency at the high limit. Intake boosting becomes necessary due to the oxygen deficiency caused by the low energy density of the reformate mixtures as it displaces intake air.
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    Exploring the Effects of Piston Bowl Geometry and Injector Included Angle on Dual-Fuel and Single-Fuel RCCI
    (ASME, 2021) Hariharan, Deivanayagam; Boldaji, Mozhgan Rahimi; Yan, Ziming; Gainey, Brian; Lawler, Benjamin; University of Alabama Tuscaloosa; Clemson University
    Reactivity control compression ignition (RCCI) is a low-temperature combustion technique that has been proposed to meet the current demand for high thermal efficiency and low engine-out emissions. However, its requirement of two separate fuel systems (i.e., a low-reactivity fuel system and a high-reactivity fuel system) has been one of its major challenges in the last decade. This leads to the single-fuel RCCI concept, where the secondary fuel (reformates of diesel) is generated from the primary fuel (diesel) through catalytic partial oxidation reformation. Following the in-depth analysis of the reformate fuel (reformates of diesel) and its benefit as the low-reactivity fuel with diesel, the effects of the start of injection (SOI) timing of diesel and the energy-based blend ratio were also studied in detail. In this study, the effects of piston profile and the injector included angles were experimentally examined using both conventional fuel pairs (gasoline-diesel and natural gas-diesel) and reformate RCCI. A validated computational fluid dynamics (CFD) model was also used for a better understanding of the experimental trends. Comparing a reentrant bowl piston with a shallow bowl piston at a constant compression ratio and SOI, the latter showed better thermal efficiency, regardless of the fuel combination, due to its 10% lower surface area for the heat transfer. Comparing the 150-degree included angle and 60-degree included angle on the shallow bowl piston, the latter showed better combustion efficiency, regardless of the fuel combination, due to its earlier combustion phasing (at constant SOI timing). The effect was particularly prominent on reformate RCCI because of its incredibly high diluent concentration, which retards the combustion further for the 150-deg injector. Later, using convergecfd, seven different injector included angles were studied at a constant SOI. With the change in injector included angle, the region of the cylinder targeted by the fuel spray varies significantly, and it was found to have a significant impact on the combustion efficiency and the engine-out emissions. As the injector included angle changed from 60-deg to 150-deg, the combustion efficiency increased by 15% and the CO, NOx, and HC emissions decreased by 96%, 70%, and 86%, respectively.
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    Investigation Into Reactivity Separation Between Direct Injected and Premixed Fuels in RCCI Combustion Mode
    (2019) Yan, Ziming; Gainey, Brian; Hariharan, Deivanayagam; Lawler, Benjamin; University of Alabama Tuscaloosa
    This experimental study focuses on the effects of the reactivity separation between the port injected fuel and the direct injection fuel, the amount of external-cooled exhaust gas recirculation (EGR), and the direct injection timing of the high reactivity fuel on Reactivity Controlled Compression Ignition (RCCI) combustion. The experiments were conducted on a light-duty, single-cylinder diesel engine with a production GM/Isuzu engine head and piston and a retrofitted port fuel injection system. The global charge-mass equivalence ratio, ϕ′, was fixed at 0.32 throughout all of the experiments. To investigate the effects of the fuel reactivity separation, different Primary Reference Fuels (PRF) were port injected, with the PRF number varying from 50 to 90. To investigate the effects of EGR, an EGR range of 0 to 55% was used. To investigate the effects of the injection timing, an injection timing window of −65 to −45 degrees ATDC was chosen.The results indicate that there are several tradeoffs. First, decreasing the port injected fuel reactivity (increasing the PRF number) delays combustion phasing, decreases the combustion efficiency by up to 9%, increases the gross indicated thermal efficiency up to 22%, enhances the combustion sensitivity to the direct injection timing, and slightly increases the UHC, CO, and NOx emissions. Second, increasing the EGR percentage delays combustion phasing, lowers the peak heat release rate, and lowers the NOx emissions. The combustion efficiency first increases and then decreases with EGR percentage for high reactivity fuels (low PRF number), but only decreases for low reactivity fuels. Finally, delaying the injection timing advances combustion phasing and increases the combustion efficiency, but decreases the gross indicated thermal efficiency and increases the NOx emissions. Across all of the experiments, delays in CA50 increase the gross indicated thermal efficiency and decrease the combustion efficiency, which represents an inherent tradeoff for RCCI combustion on a light-duty engine.