N-butanol Ratio Research Articles

Experimental investigation on the combustion and emissions characteristics of an N-butanol/CTL dual fuel engine

The effects of n-butanol/coal to liquid (CTL) dual fuel combustion mode on combustion and emissions characteristics were experimentally investigated at medium load. The CTL was produced by the Fischer-Tropsch process and the N-butanol was obtained by the biological fermentation. The optimized combustion boundary conditions mainly include n-butanol ratio, EGR rate and start of injection (SOI). The results showed that the premixed combustion ratio (PCR) of CTL is lower than the conventional diesel, which is beneficial to reduce the peak value of in-cylinder pressure and rate of pressure rise (ROPR). Port fuel injection of n-butanol improves the homogeneity of the mixture gas, which is contributing to increasing the PCR, shortening the combustion duration, thereby suppressing the generation of particles and improving the volumetricity of combustion. Introducing EGR effectively suppresses the excessive ROPR caused by the pre-injection of n-butanol and broadens the range of n-butanol premixed fraction. In the comparison of pure CTL mode, combining with the suitable EGR rate and SOI, the combustion mode of n-butanol/CTL dual fuel can simultaneously reduce NOx and particulate emissions. Among them, a higher n-butanol ratio needs to be combined with a higher EGR rate to obtain a better comprehensive emission performance, and increasing the n-butanol ratio promotes the conversion of particulate to nuclear mode. After optimization of the combustion boundary conditions, the NOx emission of the n-butanol/CTL dual fuel mode at the n-butanol ratio of 30% is reduced by 49.5%, and the particulate matter emission is reduced by 40.9%, relative to the pure CTL mode.

Glycerol valorization through production of di-glyceryl butyl ether with sulfonic acid functionalized KIT-6 catalyst

In this work, the etherification of glycerol with n-butanol catalyzed by sulfonic acid functionalized on KIT-6 mesoporous silica (SO3H-KIT-6) was investigated for the production of valuable fuel additives. The SO3H-KIT-6 catalyst was synthesized by co-condensation with different molar ratios of tetraethoxysilane and 3-mercaptopropyl(methyl)di-methoxy silane. The etherification reaction was systematically examined to determine the optimal reaction temperature, reaction time, catalyst loading, and glycerol to n-butanol ratio under autogenous pressure. The maximum glycerol conversion and di-glyceryl n-butyl ether (di-GNBE) selectivity were 59.09 and 51.50%, respectively, when the SO3H-KIT-6 catalyst with the highest acidity was applied. Interestingly, the presence of a methyl group on the catalyst surface prevented glycerol adsorption during the reaction process, leading to the inhibition of undesired product formation. The SO3H-KIT-6 catalyst could be reused up to three times, with only a 13% decrease in glycerol conversion being found. Moreover, the superior performance of the SO3H-KIT-6 catalyst for di-GNBE production was also demonstrated compared with conventional solid acid catalysts including HZSM-5, H-beta zeolite, Amberlyst-35, and Amberlyst-36.

Synthesis of n-butyl acetate via reactive distillation column using Candida Antarctica lipase as catalyst.

The reactive distillation process for the synthesis of n-butyl acetate via transesterification of ethyl acetate with n-butyl alcohol catalyzed by immobilized lipase was simulated and experimentally tested in this work. Based on the reaction kinetics, a reactive distillation process model was developed. The effects of theoretical stages number in the reaction section, the rectifying section and stripping section, reflux ratio, feed molar ratio and relative feed position on the transesterification distillation process were investigated. The transesterification of ethyl acetate with n-butyl alcohol was carried out in a small-scale reactive distillation column. The results showed that the optimal operating conditions are as follows: reaction section stages were 13, rectifying section stages were six, stripping section stages were five, reflux ratio was 1, mole ratio of ethyl acetate and n-butanol was 3:1, the feeding positions of n-butanol and ethyl acetate were at the top and bottom of the reaction section, respectively. Compared to the batch reaction with only 60% conversion of n-butanol, the reactive distillation column can improve the conversion of n-butanol (up to 93.6%).At the same time, the experiment verified that the conversion of n-butanol could still reach 72.5%, after the lipase-loaded packing storage in the reaction system at 70°C for 120days.

Effect of design parameters on performance and emissions of a CI engine operated with diesel-biodiesel- higher alcohol blends

The present study attempts to study the influences of piston geometry, butanol fumigation, EGR, injection pressure and injection timing upon the performance and emissions of a light-duty DI diesel engine fuelled with diesel, Jatropha methyl ester (JME) and 20% by vol. of n-butanol/diesel blends. Experiments were designed based on Taguchi L18 orthogonal array that considered main fuel injection timing, EGR, premixing ratio of n-butanol with diesel, injection pressure, secondary injection timing, piston geometry, main injection fuel and secondary injection fuel as factors and NOx emission, smoke opacity and BSFC as responses. The best combination of the above factor levels were predicted by using desirability function. Results indicated that B20 injected at 20°CA bTDC with an injection pressure of 200 bar under 10% EGR alongside 40% by vol. of butanol/diesel fumigation with a premixing ratio of 20% at 9°CA aTDC in the engine fitted with a torroidal piston was predicted to deliver 359.13 ppm of NOx emissions, 74.83% of smoke opacity with 1.127kg/kWh of BSFC. The tests revealed that the predictions by using desirability function were within a reasonable accuracy of 10%.

Combustion performance and emission characteristics of a diesel engine burning biodiesel blended with n-butanol

The combustion and emission characteristics of a four-cylinder direct injection diesel engine fueled with 0%, 10%, 20% or 30% blends of n-butanol and biodiesel were characterized at the loads of 0.13–1.13 MPa brake mean effective pressure (BMEP) and the speed of 1800 rpm. With the main injection time and rotation speed constant in the bench test, the cylinder pressure, heat release rate, ignition delay and the regulated or unregulated emissions were measured. The peak of HRR maximized at 0.38 MPa BMEP. The ignition delay period was prolonged in the case of n-butanol. But the combustion duration was shorten with the rising of n-butanol ratio. When n-butanol was added, more HC, NOx and acetaldehyde and less CO, 1,3-butadiene and benzene were emitted. For soot emissions, the addition of n-butanol would reduce the formation of soot. In conclusion, the addition of n-butanol improves the combustion performance while there has different changes about emission characteristics.

Investigation on Blending Effects of Gasoline Fuel with N-Butanol, DMF, and Ethanol on the Fuel Consumption and Harmful Emissions in a GDI Vehicle

The effects of three kinds of oxygenated fuel blends—i.e., ethanol-gasoline, n-butanol-gasoline, and 2,5-dimethylfuran (DMF)-gasoline-on fuel consumption, emissions, and acceleration performance were investigated in a passenger car with a chassis dynamometer. The engine mounted in the vehicle was a four-cylinder, four-stroke, turbocharging gasoline direct injection (GDI) engine with a displacement of 1.395 L. The test fuels include ethanol-gasoline, n-butanol-gasoline, and DMF-gasoline with four blending ratios of 20%, 50%, 75%, and 100%, and pure gasoline was also tested for comparison. The original contribution of this article is to systemically study the steady-state, transient-state, cold-start, and acceleration performance of the tested fuels under a wide range of blending ratios, especially at high blending ratios. It provides new insight and knowledge of the emission alleviation technique in terms of tailoring the biofuels in GDI turbocharged engines. The results of our works showed that operation with ethanol–gasoline, n-butanol–gasoline, and DMF–gasoline at high blending ratios could be realized in the GDI vehicle without any modification to its engine and the control system at the steady state. At steady-state operation, as compared with pure gasoline, the results indicated that blending n-butanol could reduce CO2, CO, total hydrocarbon (THC), and NOX emissions, which were also decreased by employing a higher blending ratio of n-butanol. However, a high fraction of n-butanol increased the volumetric fuel consumption, and so did the DMF–gasoline and ethanol–gasoline blends. A large fraction of DMF reduced THC emissions, but increased CO2 and NOX emissions. Blending n-butanol can improve the equivalent fuel consumption. Moreover, the particle number (PN) emissions were significantly decreased when using the high blending ratios of the three kinds of oxygenated fuels. According to the results of the New European Drive Cycle (NEDC) cycle, blending 20% of n-butanol with gasoline decreased CO2 emissions by 5.7% compared with pure gasoline and simultaneously reduced CO, THC, NOX emissions, while blending ethanol only reduced NOX emissions. PN and particulate matter (PM) emissions decreased significantly in all stages of the NEDC cycle with the oxygenated fuel blends; the highest reduction ratio in PN was 72.87% upon blending 20% ethanol at the NEDC cycle. The high proportion of n-butanol and DMF improved the acceleration performance of the vehicle.

The influence of mixing ratio of low carbon mixed alcohols on knock combustion of spark ignition engines

Alcohol fuels, owing to the characteristics of oxygen-containing and high octane number, are considered as one potential alternative fuel additive in spark ignition (SI) engines. In this paper, the ethanol and n-butanol are blended with gasoline to form the new low-carbon mixed alcohols-gasoline blended fuels. The effect of different mixing proportions of ethanol and n-butanol in gasoline on knock combustion and fuel economy of SI engine was studied by experiment and simulation. The results showed that with the increase of n-butanol ratio, brake specific fuel consumption (BSFC) increase, but knock index (KI) and knock intensity decrease. Moreover, crank angle delays under the same knocking condition when the engine fueled with E5-Bx and B5-Ey fuel, and the crank angle is delayed more significantly with the increase of engine speed. In addition, when the ethanol and n-butanol are blended as the same proportion in gasoline (i.e. x = y), the KI and knock intensity of E5-Bx fuel is lower than that of B5-Ey, which indicates that the B5-Ey fuel has better antiknock property. But the BSFC of B5-Ey is slightly greater than that of E5-Bx under the same operating condition, that is, the B5-Ey fuel has higher fuel consumption.

Butyl-biodiesel production from waste cooking oil: Kinetics, fuel properties and emission performance

Butyl-biodiesel is produced by the transesterification of waste cooking oil and n-butanol. The sulfamic acid, a kind of heterogeneous acid, is used as the substitute of sulfuric acid to catalyze the reaction. The yield of biodiesel can reach 95.6% at the optimal reaction conditions (molar ratio of n-butanol to oil is 10:1, catalyst amount is 1.0 wt% (based on oil), reaction temperature is 110 °C and reaction time is 2 h). Besides, a pseudo second-order reaction kinetics is also established at the temperature range of 90–110 °C and the activation energy of 80.3 kJ/mol is calculated by the Arrhenius equation. Moreover, when compared with the FAMEs, the cold flow performance of FABEs is improved and the cold filter plugging point (CFPP) of FABEs is significantly decreased from 6.5 °C to 2 °C. Finally, the bench test was also investigated to make a detail comparison of the engine performance and the CH, CO, NOx and PM emissions of FAMEs, FABEs and 0# diesel.

Investigation of the effect of adding graphene oxide, graphene nanoplatelet, and multiwalled carbon nanotube additives with n-butanol-Jatropha methyl ester on a diesel engine performance

Abstract In this article, the carbon nanomaterials; graphene oxide (GO), graphene nanoplatelets (GNPs), and multiwalled carbon nanotubes (MWCNTs) were mixed with 60% (by volume) jatropha methyl ester and 40% (by volume) n-butanol fuel (JME40B) to examine the performance and emission characteristics of a diesel engine. The GO, GNPs, and MWCNTs with a concentration of 50 mg/l were mixed with JME40B blends using ultrasonication technique. The engine was run under various loads at a constant speed of 2000 rpm. The results for JME40B blended fuel showed that the peak pressure and brake specific fuel consumption were increased up to 6%, and 22% respectively compared to pure diesel fuel. Furthermore, the addition of carbon nanomaterials with JMB40B resulted in a significant reduction in the specific fuel consumption by 35% and the engine exhaust emissions; NOx, CO, and UHC were reduced by 45%, 55%, and 50%, respectively compared to pure JME40B blends. Consequently, adding high n-butanol ratio with jatropha biodiesel fuel with the addition of carbon nanomaterials has the possibility to reach ultra-low NOx, CO, and UHC emissions meanwhile maintaining high thermal efficiency level.

Experimental study on combustion and emissions of n-butanol/biodiesel under both blended fuel mode and dual fuel RCCI mode

Oxygenated biofuels have become one of the research focuses of engines due to their renewability and improvement in combustion. There has been some studies concentrating on the dual fuel RCCI mode or blended combustion mode using biofuels in engines and valuable progress has been obtained. However, the comparison between biofuel RCCI and blended combustion modes has been rarely reported. Therefore, in current work, experimental study was conducted on a single-cylinder engine to investigate the differences between the two combustion modes fueled with biodiesel/n-butanol at different EGR rates (0%, 30%, 50%), n-butanol ratios (20%, 50%, 80%), injection timings and engine loads (low, medium, high). Results show that the ignition delay of blended mode is longer than that of RCCI mode, and more sensitive to n-butanol ratio and EGR rate. The optimum EGR rate is 30% considering efficiency and emissions for both combustion modes. Blended fuel mode can maintain high efficiency at all test loads and n-butanol ratios, the maximum indicated thermal efficiency (ITE) is up to 47.5%, while RCCI only shows comparable efficiency at high load. The problem of high maximum pressure rise rate (MPRR) that blended fuel mode faces can be addressed by retarded combustion phasing. Under current research conditions, blended fuel mode usually presents lower soot, HC, CO emissions and slight higher NOx compared with RCCI mode. Generally, blended mode has better performance when MPRR problem is addressed while RCCI mode shows the potential in load extension due to the low MPRR and flexible split ratio and injection timing.

Investigation into particle emission characteristics of partially premixed combustion fueled with high n-butanol-diesel ratio blends

Based on a 4-cylinder turbocharged intercooler diesel engine fueled with n-butanol/diesel blends, this paper investigated the effect of various parameters on emissions under the early-injection partially premixed combustion (PPC) strategy and pre-injection PPC strategy. The potential for realizing PPC with different fuel reactivity and oxygen content was evaluated. The experimental results indicated that the peak value of heat release rate (HRR) increased and the heat release duration shortened after mixing the n-butanol under the same injection timing. The start of combustion (SOC) was advanced and the proportion of premixed combustion decreased as the growth of pre-injection ratio. The heat release process was delayed when the n-butanol ratio was increased. As the growth of n-butanol ratio, the peak value of the accumulation mode particles reduced and that of the nucleation mode particles increased sharply. The geometric mean diameter (GMD) of the particles was significantly reduced when the pre-injection timing was changed from −25 to −35° CA ATDC. As the growth of the pre-injection ratio, the GMD of the particulates had a tendency to decrease. Under the same pre-injection conditions, the total number and mass concentration of the particulates both reduced obviously with the increase of n-butanol ratio.

An Effective Extract Method of Phospholipids from Antarctic Krill <em>Euphausea superba</em>

Phospholipids are one of the major bioactive ingredients of Antarctic krill Euphausea superba. A feasible and effective extraction method of Antarctic krill oil was investigated and modified by orthogonal test which the ratio of solid to liquid was 1:2.5, extraction time was 5 min, ratio of ethyl acetate (EA) and n-butanol (BuOH) was 1:1. With this method, the extract of krill oil has a higher phospholipids content of 27.7% - 42.3%, together with total oil yields of 4.15% - 6.18%.

Experimental and kinetic modeling investigation of rich premixed toluene flames doped with n-butanol.

n-Butanol is a promising renewable biofuel and has a lot of advantages as a gasoline additive compared with ethanol. Though the combustion of pure n-butanol has been extensively investigated, the chemical structures of large hydrocarbons doped with n-butanol, especially for aromatic fuels, are still insufficiently understood. In this work, rich premixed toluene/n-butanol/oxygen/argon flames were investigated at 30 Torr with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The blending ratio of n-butanol was varied from 0 to 50%, while the equivalence ratio was maintained at a quite rich value (1.75) for the purpose of studying the influence of n-butanol on the aromatic growth process. Flame species including radicals, reactive molecules, isomers and polycyclic aromatic hydrocarbons (PAHs) were identified and their mole fraction profiles were measured. A kinetic model of toluene/n-butanol combustion was developed from our recently reported toluene and n-butanol models. It is observed that the production of most toluene decomposition products and larger aromatics was suppressed as the blending ratio of n-butanol increases. Meanwhile, the addition of n-butanol generally enhanced the formation of most observed C2-C4 hydrocarbons and C1-C4 oxygenated species. The rate of production (ROP) analysis and experimental observations both indicate that the interaction between toluene and n-butanol in their decomposition processes mainly occurs at the formation of small intermediates, e.g. acetylene and methyl. In particular, the interaction between toluene and n-butanol in methyl formation influences the formation of large monocyclic aromatics such as ethylbenzene, styrene and phenylacetylene, making their maximum mole fractions decay slowly upon increasing the blending ratio of n-butanol compared with toluene and benzyl. The increase of the blending ratio of n-butanol reduces the formation of key PAH precursors such as benzyl, fulvenallenyl, benzene, phenyl and propargyl, which leads to a remarkable reduction in the formation of PAHs.

Experimental and kinetic investigation on soot formation of n-butanol-gasoline blends in laminar coflow diffusion flames

Bio-butanol has been considered to be an important alternative fuel to reduce soot emissions from gasoline engines, and it has the potential to overcome the disadvantages brought by low-carbon alcohols. In this study, the effect of n-butanol addition on soot formation in gasoline laminar diffusion flame is investigated respectively under the same fuel flow and the same carbon flow. The soot volume fraction distributions in the flames are measured using the two-color laser induced incandescence (TC-LII) technique. Furthermore, the But-TRF-PAH mechanism is constructed and used to simulate the formation and oxidation of soot precursors in the CHEMKIN zero-dimensional constant pressure reactor. The experimental results showed that n-Butanol addition can significantly reduce the soot formation, and the measured peak and average soot volume fraction both decrease linearly with the increasing n-butanol ratio. For a given n-butanol ratio, the reduction of soot under the same carbon flow (SCF) condition is only slightly smaller than that under the same fuel flow (SFF) condition, which indicates that the decreasing carbon mass flow due to n-butanol addition has little contribution to soot reduction. The simulated results showed that benzene is mainly produced via C6H5CH3+H=A1+CH3, and is mainly consumed via A1 + OH = A1- + H2O and A1 + CH3 = A1- + CH4. The production pathways of PAH is consistent for the toluene reference fuels (TRF) and n-butanol/TRF blends. The ratio of benzene accounts for toluene consumption is essentially constant, about 1/4. Thus, the n-butanol addition reducing the soot is mainly due to the dilution of the amount of aromatics (toluene in TRF) in gasoline. Furthermore, the amount of OH and HO2 radicals increases with increasing n-butanol ratio, which have an important indirect effect on the soot precursors formation.

High-temperature oxidation kinetics of iso-octane/n-butanol blends-air mixture

A chemical kinetic mechanism of n-butanol/iso-octane blends (Model BI) was established on the basis of a n-butanol reaction submechanism and part of a high-temperature oxidation mechanism of iso-octane. Model BI was validated against laminar flame speeds, ignition delay times and JSR data, and proved to be applicable and reliable. It also found that the laminar flame speed of blends increased linearly and monotonically with the increasing ratio of n-butanol. Then detailed kinetic pathway analysis of n-butanol/iso-octane blends were performed based on Model BI to find out the reason for the accelerating effect of added n-butanol. The most influential elementary reactions were determined for the blend, and the laminar flame speed is largely negative related to the concentration of iC4H8, C3H6 and CH3, while C2H4 and C2H3 contribute to the promotion of laminar flame speeds. Flame structures of n-butanol blending with iso-octane were also computed and correspond to the kinetic pathway analysis.

Study on the knock tendency and cyclical variations of a HCCI engine fueled with n-butanol/n-heptane blends

The homogeneous charge compression ignition (HCCI) combustion operation is conducted in the 2nd cylinder of a natural-aspirated four-stroke diesel engine. In the HCCI combustion mode, the n-butanol, n-heptane and their blends are injected into the intake port to form a lean homogeneous air-fuel mixture, which is consumed by the autoignition after compression. The objective of this study is to investigate the knock tendency and the cyclical variations of the HCCI engine. Experimental results show that the volume fraction of n-butanol affects the knock tendency greatly, which obviously decreases as the n-butanol volume fraction increases. The knocking combustion in the HCCI combustion is characterized by the high heat release rate (HRR). Both elevating the engine speed and raising the intake temperature contributes to an obvious increase in HRR and the knock tendency. But the HRR and knock tendency may slightly decrease when the engine speed reaches to 1400rev/min and intake temperature reaches to 160°C. Furthermore, the knock tendency can be weakened by increasing the excess air-fuel ratio. Cyclical variations of the HCCI engine are quantified by the coefficient of variation for the peak pressure (COVPmax) and it exhibits an almost opposite trend to the knock tendency. The COVPmax may considerably increase along with either increasing the blending ratio of n-butanol or increasing the excess air-fuel ratio. Moreover, it is reveled that the COVPmax is sensitive to the relative position of peak HRR. The cyclical variations may dramatically reduce when the peak HRR timing gradually approaches to the combustion center (CA50).

Investigation on the effects of pilot injection on low temperature combustion in high-speed diesel engine fueled with n-butanol–diesel blends

The effect of pilot injection timing and pilot injection mass on combustion and emission characteristics under medium exhaust gas recirculation (EGR (25%)) condition were experimentally investigated in high-speed diesel engine. Diesel fuel (B0), two blends of butanol and diesel fuel denoted as B20 (20% butanol and 80% diesel in volume), and B30 (30% butanol and 70% diesel in volume) were tested. The results show that, for all fuels, when advancing the pilot injection timing, the peak value of heat release rate decreases for pre-injection fuel, but increases slightly for the main-injection fuel. Moreover, the in-cylinder pressure peak value reduces with the rise of maximum pressure rise rate (MPRR), while NOx and soot emissions reduce. Increasing the pilot injection fuel mass, the peak value of heat release rate for pre-injected fuel increases, but for the main-injection, the peak descends, and the in-cylinder pressure peak value and NOx emissions increase, while soot emission decreases at first and then increases. Blending n-butanol in diesel improves soot emissions. When pilot injection is adopted, the increase of n-butanol ratio causes the MPRR increasing and the crank angle location for 50% cumulative heat release (CA50) advancing, as well as NOx and soot emissions decreasing. The simulation of the combustion of n-butanol–diesel fuel blends, which was based on the n-heptane–n-butanol–PAH–toluene mixing mechanism, demonstrated that the addition of n-butanol consumed OH free radicals was able to delay the ignition time.

Experimental investigation of n-butanol/diesel fuel blends and n-butanol fumigation – Evaluation of engine performance, exhaust emissions, heat release and flammability analysis

The aim of this paper is to investigate and compare the effects of n-butanol/diesel fuel blends (nBDFBs) and n-butanol fumigation (nBF) on the engine performance and exhaust emissions in a turbocharged automobile diesel engine. Also, evaluations based on heat release and flammability analysis have been done. Experiments have been performed for various n-nBDFBs and nBF at different engine speeds and loads. For nBDFBs and nBF tests; nB2, nB4 and nB6 and nBF2, nBF4 and nBF6n-butanol percentages were selected. Here, for example nB2 and nBF2 contains 2% n-butanol and 98% diesel fuel by volume respectively. The test results showed that smoke decreases significantly by applying both of these two methods. However, decrement ratios of smoke for fumigation method are higher than that of blend method. NOx emission decreases for nB2, but it increases for nB4 and nB6 at selected engine speeds and loads. NOx emission decreases generally for nBF. For nB2 and nB4, BSFC decreases slightly but it increases for nB6. For nBF, BSFC increases at all of the test conditions. Adding n-butanol to diesel fuel becomes expensive for two methods. For nBDFBs, heat release rate (HRR) diagrams exhibit similar typical characteristic to NDF. However, for nBF, HRR shows slightly different pattern from NDF and a double peak is observed in the HRR diagram. The first peak occurs earlier than NDF and the second peak takes places later. In addition, this diagram shows that the first peak becomes larger and the second peak diminishes as n-butanol ratio is increased. Because of pilot injection of diesel fuel, it can be seen that diesel fuel could be exceed the lower flammability limit and self ignition could be occur. Thus, pre-combustion occurs at the interval of ∼(−20 to −10)°CA.

Upgrading Fast Pyrolysis Bio-Oil Quality by Esterification and Azeotropic Water Removal

Fast pyrolysis bio-oil has unfavorable properties that restrict its use in many applications. Among the main issues are high acidity, instability, and water and oxygen content, which give rise to corrosiveness, polymerization during storage, and a low heating value. Esterification and azeotropic water removal can improve all of these properties. In this work, low acidity bio-oils were produced from fast pyrolysis bio-oil via esterification with methanol or n-butanol. Esterification conversion was enhanced by azeotropic water removal prior to and/or during esterification. An additional hydrocarbon entrainer (n-heptane or petroleum ether) was required for efficient water removal. The product oils had total acid numbers ranging from 5 to 10 mg KOH/g and pH values from 4.0 to 5.6. The best results were obtained with 1:0.9:0.1 wt ratio of bio-oil, n-butanol, and n-heptane and p-toluenesulfonic acid (p-TSA) as catalyst. Removal of homogeneous catalyst (2 wt % p-toluenesulfonic acid (p-TSA)) was attempted by precipitation, centrifugation, and water washing, but only 41–82 wt % of the catalyst could be recovered from the product oil based on sulfur content. Solid acid catalysts were more efficient with methanol than n-butanol in dry conditions. An organic base (triethylamine) was tested for neutralizing the methanol esterified bio-oil’s residual acidity. Nitrogen content increased by 0.1–0.4 wt % when pH values of 6–8 were obtained.

Effects of higher ratios of n-butanol addition to diesel–vegetable oil blends on performance and exhaust emissions of a diesel engine

n-Butanol is a promising next generation alternative fuel for stabilizing diesel fuel–vegetable oil blends at low temperatures. In this study, the effects of higher n-butanol contents in diesel fuel–vegetable oil blends in a diesel engine were investigated. Ternary blends of diesel fuel (D)–cotton oil (CtO)–n-butanol (nB) as percentages (vol.%) of 60%D–10%CtO–30%nB (TB1), 50%D–30%CtO–20%nB (TB2), 30%D–30%CtO–40%nB (TB3), 30%D–10%CtO–60%nB (TB4) and 20%D–20%CtO–60%nB (TB5) were selected in the soluble area of the ternary phase diagram for low temperature (−15 °C) operability. The tests were conducted employing each of the above ternary blends and diesel fuel, with the engine operating at full load and eight different engine speeds between 1800 and 4400 rpm. Increasing presence of n-butanol in the blends improved density, kinematic viscosity and cold filter plugging point (CFPP), while deteriorated cetane number (CN) and heating value of the ternary blends. Experimental test results of ternary blends showed that average brake torque, brake power, brake thermal efficiency (BTE) and exhaust gas temperature decreased, while brake specific fuel consumption (BSFC) increased with increasing presence of n-butanol in the blends. Addition of n-butanol to diesel fuel–vegetable oil blends increased oxides of nitrogen (NO and NO2) formations, while drastically decreasing formation of carbon monoxide (CO) and hydrocarbon (HC) emissions. TB4 and TB5, which have the highest ratio of n-butanol, are promising candidate for decreasing CO and HC emissions at the expense of increasing BSFC.