Experimental study on stoichiometric laminar flame velocities and Markstein lengths of methane and PRF95 dual fuels

Natural gas is one of the most promising alternative fuels. The main constituent of natural gas is methane. The slow burning velocity of methane poses significant challenges for its utilization in future energy efficient combustion applications. Methane-gasoline dual fuelling has the potential to improve methane’s combustion. The fundamental combustion characteristics of a methane-gasoline Dual Fuel (DF) blend needs further investigation. In the current experimental study, the relationship between laminar flame velocity and Markstein length, with the ratio of gas to liquid in a DF blend has been investigated using spherical flames in a constant volume combustion vessel. A binary blend of primary reference fuels (PRF95) was used as the liquid fuel. Methane was added to PRF95 in three different energy ratios 25%, 50% and 75%. Values of the stoichiometric laminar flame velocities and Markstein lengths are measured at pressures of 2.5, 5, 10 Bar and a temperature of 373 K. It has been found that with a 25% increase in the DF ratio, the Markstein length is reduced by 15%, 21%, 32% at a pressure of 2.5, 5 and 10 Bar respectively whereas at the same pressures the laminar flame velocity is reduced by 2%, 3% and 5%. The flame evolution at the early stages of combustion is found to be faster with an increase in the DF ratio, and gradually as the flame develops it becomes slower

Efficient display of active lipase LipB52 with a Pichia pastoris cell surface display system and comparison with the LipB52 displayed on Saccharomyces cerevisiae cell surface

<p>Abstract</p> <p>Background</p> <p>For industrial bioconversion processes, the utilization of surface-displayed lipase in the form of whole-cell biocatalysts is more advantageous, because the enzymes are displayed on the cell surface spontaneously, regarded as immobilized enzymes.</p> <p>Results</p> <p>Two <it>Pichia pastoris </it>cell surface display vectors based on the flocculation functional domain of FLO with its own secretion signal sequence or the α-factor secretion signal sequence were constructed respectively. The lipase gene <it>lipB52 </it>fused with the <it>FLO </it>gene was successfully transformed into <it>Pichia pastoris </it>KM71. The lipase LipB52 was expressed under the control of the <it>AOX1 </it>promoter and displayed on <it>Pichia pastoris </it>KM71 cell surface with the two <it>Pichia pastoris </it>cell surface display vectors. Localization of the displayed LipB52 on the cell surface was confirmed by the confocal laser scanning microscopy (CLSM). The LipB52 displayed on the <it>Pichia pastoris </it>cell surface exhibited activity toward <it>p</it>-nitrophenol ester with carbon chain length ranging from C₁₀to C₁₈, and the optimum substrate was <it>p</it>-nitrophenol-caprate (C₁₀), which was consistent with it displayed on the <it>Saccharomyces cerevisiae </it>EBY100 cell surface. The hydrolysis activity of lipase LipB52 displayed on <it>Pichia pastoris </it>KM71-pLHJ047 and KM71-pLHJ048 cell surface reached 94 and 91 U/g dry cell, respectively. The optimum temperature of the displayed lipases was 40°C at pH8.0, they retained over 90% activity after incubation at 60°C for 2 hours at pH 7.0, and still retained 85% activity after incubation for 3 hours.</p> <p>Conclusion</p> <p>The LipB52 displayed on the <it>Pichia pastoris </it>cell surface exhibited better stability than the lipase LipB52 displayed on <it>Saccharomyces cerevisiae </it>cell surface. The displayed lipases exhibited similar transesterification activity. But the <it>Pichia pastoris </it>dry cell weight per liter (DCW/L) ferment culture was about 5 times than <it>Saccharomyces cerevisiae</it>, the lipase displayed on <it>Pichia pastoris </it>are more suitable for whole-cell biocatalysts than that displayed on <it>Saccharomyces cerevisiae </it>cell surface.</p

Experimental investigation on the Laminar burning velocities and Markstein lengths of methane and PRF95 dual fuels

© 2016 American Chemical Society.Natural gas is a promising alternative fuel. The main constituent of natural gas is methane. The slow burning velocity of methane poses significant challenges for its utilization in future energy efficient combustion applications. The effects of methane addition to PRF95 on the fundamental combustion parameters, laminar burning velocity (Su0) and Markstein length (Lb), were experimentally investigated in a cylindrical combustion vessel at equivalence ratios of 0.8, 1, and 1.2, initial pressures of 2.5, 5, and 10 bar, and a constant temperature of 373 K. Methane was added to PRF95 in three different energy ratios 25%, 50%, and 75%. Spherically expanding flames were used to derive the flow-corrected flame velocities, from which the corresponding Lb and Su0 were obtained. The flame velocities were corrected for the motion of burned gas induced by the cylindrical confinement. It has been found that at stoichiometric conditions there is a linear decrease in Lb and Su0 with the dual fuel (DF) ratio in all investigated pressures. At rich conditions, all DFs resulted in having lower Su0 as compared to methane and to a larger extent PRF95. The values of Lb for all DFs were lower than methane and comparable to those of PRF95. At lean conditions, the values of Lb for all DFs are biased toward those of methane whereas the values of Su0 are found to be higher than those of PRF95 at pressures of 2.5 and 5 bar. At 10 bar both Lb and Su0 reduce with DF ratio although Su0 of all DFs converge to that of PRF95. The findings of the current study indicate a distinct synergy in the utilization of dual fueling in future lean burn energy efficient combustion applications

Experimental study on the burning rate of Methane and PRF95 dual fuels

Natural gas as an alternative fuel offers the potential of clean combustion and emits relatively low CO2 emissions. The main constitute of natural gas is methane. Historically, the slow burning speed of methane has been a major concern for automotive applications. Literature on experimental methane–gasoline Dual Fuel (DF) studies on research engines showed that the DF strategy is improving methane combustion, leading to an enhanced initial establishment of burning speed even compared to that of gasoline. The mechanism of such an effect remains unclear. In the present study, pure methane (representing natural gas) and PRF95 (representing gasoline) were supplied to a constant volume combustion vessel to produce a DF air mixture. Methane was added to PRF95 in three different energy ratios 25%, 50% and 75%. Experiments have been conducted at equivalence ratios of 0.8, 1, 1.2, initial pressures of 2.5, 5 and 10 bar and a temperature of 373K. At stoichiometric conditions, experiments in an SI engine have been also performed. It has been found that methane and all DFs have their fastest burning rate at stoichiometric conditions whereas PRF95 at rich conditions (Φ=1.2). At lean conditions (Φ=0.8), all DFs resulted in faster combustion than PRF95, whereas methane is the slowest of all. At rich conditions, DF75 and DF50 are slower than methane. The transition mechanism between the constant volume combustion experiments and those in the engine environment resulted in a larger increase in the burning speed of methane and all DFs in comparison to that of the liquid fuel

Experimental Investigation on the Laminar Burning Velocities and Markstein Lengths of Methane and PRF95 Dual Fuels

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.energyfuels.6b00644© 2016 American Chemical Society.Natural gas is a promising alternative fuel. The main constituent of natural gas is methane. The slow burning velocity of methane poses significant challenges for its utilization in future energy efficient combustion applications. The effects of methane addition to PRF95 on the fundamental combustion parameters, laminar burning velocity (Su0) and Markstein length (Lb), were experimentally investigated in a cylindrical combustion vessel at equivalence ratios of 0.8, 1, and 1.2, initial pressures of 2.5, 5, and 10 bar, and a constant temperature of 373 K. Methane was added to PRF95 in three different energy ratios 25%, 50%, and 75%. Spherically expanding flames were used to derive the flow-corrected flame velocities, from which the corresponding Lb and Su0 were obtained. The flame velocities were corrected for the motion of burned gas induced by the cylindrical confinement. It has been found that at stoichiometric conditions there is a linear decrease in Lb and Su0 with the dual fuel (DF) ratio in all investigated pressures. At rich conditions, all DFs resulted in having lower Su0 as compared to methane and to a larger extent PRF95. The values of Lb for all DFs were lower than methane and comparable to those of PRF95. At lean conditions, the values of Lb for all DFs are biased toward those of methane whereas the values of Su0 are found to be higher than those of PRF95 at pressures of 2.5 and 5 bar. At 10 bar both Lb and Su0 reduce with DF ratio although Su0 of all DFs converge to that of PRF95. The findings of the current study indicate a distinct synergy in the utilization of dual fueling in future lean burn energy efficient combustion applications

Pharmacokinetics of lansoprazole injection in peptic ulcer and healthy volunteers

The pharmacokinetics of lansoprazole after a single intravenous dose of 30 mg was determined in 10 healthy volunteers and 10 peptic ulcers patients. In this work, a liquid-liquid extraction and enrichment method with RP-HPLC determination route was taken with high sensitivity and low limit detection of 5 ng/mL. The concentration-time curves in the two groups were best fitted to a two-compartment model, but their main kinetic parameters were remarkably different between healthy and ulcers volunteers. The mean maximum plasma concentration (Cmax ) and area under the curve (AUC0t ) were increased from 975.8 ng/mL to 1298.7 ng/mL and from 1439 ng·h/mL to 2301 ng·h/mL, respectively, and peak time (tmax ) decreased from 0.36 h to 0.26 h. Meanwhile, the half life (t1/2 ) prolonged from 2.25 h to 2.91 h and the clearance (CL) reduced from 20.04 L/h to 13.96 L/h. That variability of lansoprazole pharmakinetic parameter indicates that ulcers have significant effect on its metabolic process.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Experimental investigations on emission characteristics of heavy-duty hybrid electric vehicles

The emission characteristics under different operating modes (engine mode and hybrid mode) and different test cycles (C-WTVC and CHTC) of a heavy-duty hybrid electric dump truck was investigated on the chassis dynamometer. The emission performance was recorded using Portable Emissions Measurement System (PEMS) and analyzed combined with the characteristic parameters of the test conditions. It is found that the NOx emission under hybrid mode is higher than that under engine mode, while the CO emission under hybrid mode is lower than engine mode. Under engine mode, the NOx emission of CHTC is higher than that of C-WTVC. However, under hybrid mode, the NOx emission of CHTC is lower than C-WTVC. Analysis of CO emission characteristics shows that under engine mode, CO emission is concentrated at low speed and small load condition, while under hybrid mode, CO emission is concentrated at high speed and large load condition

Research on emission fuel consumption cooperative test of heavy-duty gasoline vehicle under cold start

This paper conducts emissions and fuel consumption collaborative test of heavy-duty gasoline vehicle, which based on cold start with chassis dynamometer, the data analysis uses cold and hot coefficient weighting to evaluate the results. The research shows that the cold start has a great influence on the pollutants and CO2 emissions, which is mainly reflected in the 86.1% higher THC, 98.2% higher NOX, 65.0% higher CO and 34.8% higher CO2 of cold start cycle emissions compared with the hot start cycle emissions. The cold and heat weighted evaluation method can not only assessmen cold start cycle emissions, but also reasonably reflect the impact degree of cold start factors on emissions. The fuel consumption of cold start is 7.2% higher than that of hot start, the cold and heat weighted fuel consumption compared to the average fuel consumption of hot state is 1.0% higher. Therefore, it is necessary to add collaborative testing of emissions and fuel consumption of heavy-duty gasoline vehicles during cold start in the next phase of the standar

Poboljšanje enzimske proizvodnje cefaleksina upotrebom velikih koncentracija supstrata i uklanjanjem produkata reakcije kompleksiranjem in situ

Cephalexin (CEX) was synthesized with 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) and D(–)-phenylglycine methyl ester (PGME) using immobilized penicillin G acylase from Escherichia coli. It was found that substrate concentration and in situ product could remarkably influence the ratio of synthesis to hydrolysis (S/H) and the efficiency of CEX synthesis. The optimal ratio of enzyme to substrate was 65 IU/mM 7-ADCA. High substrate concentration improved the 7-ADCA conversion from 61 to 81 % in the process without in situ product removal (ISPR), while in the synthetic process with ISPR, high substrate concentration increased the 7-ADCA conversion from 88 to 98 %. CEX was easily separated from CEX/β-naphthol complex and its purity and overall yield were 99 and 70 %, respectively.Primjenom imobilizirane Penicilin-G-acilaze iz bakterije Escherichia coli sintetiziran je cefaleksin (CEX) iz 7-amino-3-deacetoksicefalosporanske kiseline (7-ADCA) i D(-)-fenilglicin-metilnog estera (PGME). Koncentracije supstrata i produkta in situ mogu znatno utjecati na omjer sinteze i hidrolize (S/H) i djelotvornost sinteze cefaleksina. Optimalni omjer enzima i supstrata iznosio je 65 IU/mM 7-ADCA. Velika koncentracija supstrata poboljšala je konverziju 7-ADCA sa 61 na 81 % u procesu bez uklanjanja produkta in situ (ISPR), a s 88 na 98 % u procesu sa ISPR. Cefaleksin je lako uklonjen iz kompleksa CEX/β-naftol, a dobiveni je proizvod imao čistoću od 99 % i ukupni prinos od 70 %