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Effects of variable O2 concentrations and injection pressures on the combustion and emissions characteristics of the petro-diesel and hydrotreated vegetable oil-based fuels under the simulated diesel engine condition
(2018-12-01)
Vo, C.
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Charoenphonphanich, C.
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Karin, P.
;
Susumu, S.
;
Hidenori, K.
This experimental research investigates the effects of variable O<inf>2</inf> concentrations and injection pressures on the combustion and emissions characteristics of the diesel (B7) and the hydrotreated vegetable oil (HVO)-based fuels. The O<inf>2</inf> concentrations included 21%, 15% and 10% O<inf>2</inf>, while the injection pressures were 80 and 120 MPa. The experimental fuels were the diesel fuel (B7), the neat HVO, the 20%, 50% and 80% HVO (by mass fraction) blended with the diesel. The experiments were carried out in a rapid compression-expansion machine (RCEM) under the direct injection (DI) diesel combustion condition. The analysis was undertaken using the two-color method. The experimental results indicated that the ignition delay, the heat release rate, the flame temperature, the soot density-KL factor, the NO<inf>x</inf> and soot-out emissions were inversely correlated to the HVO fraction in the blend. In addition, the findings revealed the similar flame profiles in which the higher flame temperature region and the darker KL density were concentrated around the spray flame upstream, regardless of the HVO mixing ratio. Besides, the decrease in the O<inf>2</inf> concentration resulted in the lower heat release rate, integral heat release, flame temperature, KL factor and NO<inf>x</inf> emissions but the longer ignition delay and higher soot concentration, with the highest soot concentration observed under the 15% O<inf>2</inf> environment. Nevertheless, the higher pressure differential (i.e. between the injection pressure and the ambient pressure) contributed to the shorter ignition delay, higher heat release rate, early peak of the flame temperature, wider combustion area, faster soot oxidation rate and higher NO<inf>x</inf> production.
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Nickel sulfide, nickel phosphide and nickel carbide catalysts for bio-hydrotreated fuel production
(2017-11-01)
Phimsen, Songphon
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Kiatkittipong, Worapon
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Yamada, Hiroshi
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Tagawa, Tomohiko
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Kiatkittipong, Kunlanan
A series of nickel catalysts i.e. nickel sulfide (NiS), nickel phosphide (NiP) and nickel carbide (NiC) was investigated for hydrotreating of spent coffee oil to produce bio-hydrotreated fuel (BHF). Catalytic tests were carried out at 375–425 °C and 20–40 bar of initial H<inf>2</inf> pressure (before heating) with reaction time of 0–3 h. The activity of the catalysts are in the order of NiC > NiP > NiS; however NiC tended to promote cracking reaction resulting in high gasoline and gaseous yields. On the other hand, although NiS gives the lowest oil conversion, it is favorable to diesel yield with lowest methanation and cracking activity. Compared with decarboxylation (DCO<inf>2</inf>) and hydrodeoxygenation (HDO), decarbonylation (DCO) was the major route for deoxygenation of coffee oil for all the catalysts. The ratio of (DCO + DCO<inf>2</inf>) to HDO (as represented by C<inf>n-1</inf>/C<inf>n</inf>) decreased in the order NiS > NiC > NiP. Ketones as intermediate products (ca. 3 wt%) were detected in case of NiP. They could be generated via rearrangement of alcohol and keto-enol tautomerism. Significant amount of aromatics (4 wt%) with some isomerization products (0.9 wt%) can also be observed in NiS catalyzed liquid products while trace amount of these compounds were detected for NiP and NiC catalysts. Physiochemical analysis of the diesel fraction exhibited satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL. Since main products are straight chain hydrocarbons, high cetane index (>110) could be achieved.
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Optical study on combustion characteristics of hydrotreated vegetable oil and blends under simulated CI engine conditions and various EGR
(2017-09-01)
Chau, Vo Tan
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Chinda, Charoenphonphanich
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Karin, Preechar
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Sato, Susumu
;
Kosaka, Hidenori
Soot and NO<inf>x</inf> emissions are the inherent combustion characteristics of diesel engines. The modification of fuel property makes for an interesting study of methods for elimination of soot and NO<inf>x</inf> emissions. HVO and blends of 20 %, 50 %, 80 % by mass of HVO with commercial diesel fuel (mixed 7 % FAME), in combination with various EGR conditions were carried out to evaluate soot and NO<inf>x</inf> formation, as well as combustion characteristics of HVO blends in RCEM. The obtained results revealed that ignition delay, flame temperature, NO<inf>x</inf> and soot concentration decreased as HVO percentage increased. Mixing ratios of HVO with diesel showed a similar flame profile at baseline condition, higher flame temperature and darker soot density-KL regions were distributed on the upstream of spray flame. HVO displayed a slightly lower in-flame temperature and KL density, which led to a decrease of 33 % and 15.9 % of NO<inf>x</inf> and soot concentration, respectively, compared to diesel. By applying higher EGR levels, a reduction of heat release rate, flame temperature and NO<inf>x</inf> emissions were recorded. Also observed was an increase in ignition delay and soot concentration. Notably, soot at 10 % O<inf>2</inf> concentration was lower than that of 15 % O<inf>2</inf> concentration.
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Oil extracted from spent coffee grounds for bio-hydrotreated diesel production
(2016-10-15)
Phimsen, Songphon
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Kiatkittipong, Worapon
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Yamada, Hiroshi
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Tagawa, Tomohiko
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Kiatkittipong, Kunlanan
Oil extracted from spent coffee grounds is utilized as a renewable source for bio-hydrotreated fuel production. In the present work, oil yield up to 13% can be obtained by Soxhlet extraction with hexane as a solvent. As the extracted oil contained high content of free fatty acids (6.14%), therefore one step alkali-catalyzed for ester based biodiesel production is impractical. Hydrotreating of extracted oil was performed over two catalysts i.e. NiMo/γ-Al<inf>2</inf>O<inf>3</inf> and Pd/C with different operating parameters i.e. reaction time, operating temperature, and H<inf>2</inf>/oil. It was found that the reaction time of 2 h and the reaction temperature of 400 °C are favorable operating conditions. The liquid products mostly consisted of n-pentadecane and n-heptadecane, which contain one carbon atom shorter than the corresponding fatty acid (C<inf>n−1</inf>) i.e. palmitic and stearic acid, respectively. Unfavorable cracking of diesel product is pronounced at high temperature and prolonged reaction time. In addition, although increased H<inf>2</inf>/oil promoted overall reaction and hydrodeoxygenation activity (C<inf>n−1</inf>/C<inf>n</inf> decreased) for both catalysts, hydrocracking is enhanced over Pd/C, leading to significant increase in gasoline yield. Moreover, Pd/C gave higher olefin content in liquid product (22.3 wt%) than NiMo/γ-Al<inf>2</inf>O<inf>3</inf> (4.8 wt%). However, NiMo/γ-Al<inf>2</inf>O<inf>3</inf> shows higher isomerization activity. The amount of isoparaffins catalyzed by NiMo/γ-Al<inf>2</inf>O<inf>3</inf> and Pd/C were 10.8 and 1.7 wt%, respectively. Physiochemical analysis of the diesel fraction exhibit satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL, while the cetane index was much higher than conventional diesel.
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Diesel-like hydrocarbon production from hydroprocessing of relevant refining palm oil
(2013-05-22)
Kiatkittipong, Worapon
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Phimsen, Songphon
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Kiatkittipong, Kunlanan
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Wongsakulphasatch, Suwimol
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Laosiripojana, Navadol
This paper demonstrates the initiated use of relevant refining palm oil for bio-hydrogenated diesel production. The conversions of crude palm oil (CPO) and its physical refining including degummed palm oil (DPO) and palm fatty acid distillate (PFAD) to diesel fuel by hydroprocessing were studied. The effects of operating parameters (i.e. reaction time, operating temperature, and pressure) and catalyst (i.e. Pd/C and NiMo/γ-Al<inf>2</inf>O<inf>3</inf>) were examined in order to determine suitable operating condition for each feedstock. It was found that the hydroprocessing of CPO with Pd/C catalyst at 400 C, 40 bar, and reaction time of 3 h provides the highest diesel yield of 51%. When gum which contains phospholipid compounds is removed from CPO, namely DPO, the highest diesel yield of 70% can be obtained at a shorter reaction time (1 h). In the case of PFAD, which consists mainly of free fatty acids, a maximum diesel yield of 81% could be observed at milder conditions (375 C with the reaction time of 0.5 h). The main liquid products are n-pentadecane and n-heptadecane, having one carbon atom shorter than the corresponding fatty acids according to decarboxylation/decarbonylation pathways. Pd/C catalyst shows good catalytic activity for fatty acid feedstocks but becomes less promising for triglyceride feedstocks when compared to NiMo/γ-Al<inf>2</inf>O<inf>3</inf>. © 2013 Elsevier B.V.

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