期刊导航

Totally found 1358 items.

  • [期刊] Effects of a wave-shaped piston bowl geometry on the performance of heavy duty Diesel engines fueled with alcohols and biodiesel blends
    The effects of a new wave-shaped piston bowl design on combustion characteristics and engine out emissions were tested in a heavy duty Diesel engine fueled with conventional Diesel and fossil-free blends containing n-butanol, n-octanol, 2-ethylhexanol, hydrotreated vegetable oil, and rapeseed methyl ester. The compositions of the blends were chosen such that their cetane numbers matched that of fossil Diesel. Engine experiments were performed at four operating points from the European Stationary Cycle, with no modification of engine settings when switching between different fuels. A standard piston with omega geometry was tested using fossil Diesel and the fossil-free nBu30H (30% n-butanol and 70% hydrotreated vegetable oil by volume) blend, and the results obtained were compared to those achieved with the wave piston. In general, the fossil-free blends yielded significantly lower soot emissions than fossil Diesel but slightly higher NOx emissions. Relative to the standard piston, the wave piston accelerated the combustion of both Diesel and fossil-free blends, especially the diffusion combustion. The wave piston's positive effects on thermal efficiency and soot emissions were more pronounced for conventional Diesel fuel than for oxygenated nBu30H. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Effect of different co-solvents on biodiesel production from various low-cost feedstocks using Sr-Al double oxides
    The main objective of the present paper comprises the investigation of biodiesel production from low-cost feedstock such as lard oil and waste cooking oil (WCO) using Sr-Al double oxides. Nanocatalyst was characterised FTIR, XRD, SEM, TEM, BET and XPS. The Sr:Al with 3:1 M ratio showed the best catalytic activity in the conversion of both oils to fatty acid methyl ester. The effect of acetone and tetrahydrofuran (THF) as a co-solvent for transesterification were compared and the best result was obtained with 5% THF. The mutual effect of the nanocatalyst and co-solvent on biodiesel production was investigated. The characterisation of biodiesel synthesised from lard oil and WCO was performed with GC-MS, H-1 and C-13 NMR. Moreover, the optimum reaction parameters for transesterification reaction was analysed and the yield was determined by H-1 NMR. The maximum yield of 99.7% and 99.4% of lard oil methyl ester and WCO biodiesel were observed with a 0.9 wt% catalyst amount, 1:5.5 oil to methanol ratio in a reaction time of 45 min at 50 degrees C and 60 degrees C, respectively. The properties of biodiesel from lard oil and WCO were determined by the EN 14214 method. The regeneration, characterisation and reusability of regenerated catalyst was observed. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Thermo-physical investigation and experimental discharge characteristics of lauryl alcohol as a potential phase change material for thermal management in buildings
    This article focuses on the investigation of thermo-physical properties of lauryl alcohol, an organic fatty alcohol as a potential phase change material for thermal management in buildings. The thermal properties of lauryl alcohol over repeated accelerated thermal cycles were investigated by using differential scanning calorimetry. The chemical stability was studied using Fourier transform infrared spectroscopy. The commonly used heat exchanger construction materials such as copper, aluminium and stainless steel 316 were subjected to corrosion analysis and the results were presented. Further, the experimental discharge characteristics of lauryl alcohol as phase change material in a prototype test chamber with internal and external load were performed. In case of internal load condition, the internal chamber air temperature is a key factor for the temperature drop in the chamber and in case of external load condition, better results are obtained in experiments conducted with high inlet temperature and low inlet air velocity. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Toluene microwave cracking and reforming over bio-char with in-situ activation and ex-situ impregnation of metal
    Removal of biomass tar is of importance for biomass gasification technology, since the existence of tar can cause tremendous problems, such as lowering heat transfer efficiencies and blocking the filters and pipes, etc. A typical one-ring aromatic hydrocarbon (i.e., toluene) is chosen as model compounds to investigate tar cracking and reforming performance with microwave heating, catalyzed by biomass-derived char (Bio-char). The adopted chars consist of original char obtained by microwave or electrical heating, an in-situ activated char as well as metal-impregnated char. For the cracking process, original char achieved with microwave heating exhibits better catalytic activity, compared to that achieved with electrical heating. It is further compared activated char is more active to toluene cracking and an activated char impregnated by Ni shows the most desirable performance to this process. A process of mixed reforming comprised by steam and dry reforming presents an evident superiority in terms of toluene conversion and catalyst stability, which can achieve an average conversion of 95.19% and a minor mass loss of 2.2% occurred in the used char during 120 min. It is calculated energy efficiency of a microwave-assisted combined reforming system at lab-scale is up to 57.8%. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Synergies between the microwave reactor and CaO/zeolite catalyst in waste lard biodiesel production
    The quest for efficient and sustainable route for biodiesel production motivates the investigation of synergies between microwave reactor and calcium oxide (CaO) loaded on zeolite in waste lard biodiesel (WLB) production. The optimum concentration of the precursor used in the impregnation of the zeolite was practically determined. The resultant CaO/zeolite was characterized using some classical techniques and the characterized catalyst in synergy with the microwave reactor was used to optimize and model the biodiesel production process and the reaction optimum conditions in relation to CaO/zeolite amount, microwave power, methanol/oil ratio and time as independent variables were established (8% (wt./vol), 595 Watts, 30:1 and 1.25 h respectively) using central composite design. The conditions generated a maximum WLB yield of 90.89% signifying that the synergies between the reactor and the synthesized catalyst result in an efficient biodiesel production method. Additionally, the catalyst is shown to be easily separated from the reaction product and has the potential to be recycled a number of times under the optimum conditions. This study establishes synergies between microwave reactor system and heterogeneous CaO/zeolite catalyst that result in an economically feasible route for production of an efficient and sustainable WLB. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Study of the tribological properties the mixture of soybean oil and used (waste) frying oil fatty acid methyl ester under boundary lubrication conditions
    This study has been conducted with the purpose of studying the tribological properties the mixture of soybean oil and used frying oil the Fatty Acid Methyl Esters(FAMEs) under boundary lubrication conditions. Tests have been conducted between steel ball and the journal bearing material sample connecting to the disc of Pin-on-Disc Test apparatus. It was selected experimental parameters such as 5, 10 and 20 N loads, 100, 300, 500 rpm sliding velocities and 500m sliding distance. The surface roughness of the samples has been measured prior to and after each test. Wear rate has been measured through mass loss method prior to and after each test. Also, specific wear rates (w(s)) of the test specimens were calculated. SEM and EDS analyses were also conducted to wear contact surfaces. When all the friction coefficient (mu) values acquired from boundary lubrication conditions are compared to mu values acquired from dry (lubricant-free) test conditions, very lower friction coefficients have been achieved. Usage of the mixture of soybean oil and used frying oil FAMEs as lubricant candidates are quite good a performance under boundary and/or mixed lubrication. It has also been observed that with the increase of load, specific ws values are generally decreasing. (c) 2019 Published by Elsevier Ltd.
  • [期刊] Selective hydrogenolysis of lignin-derived aryl ethers over Co/C@N catalysts
    Low aromaticity and a large number of oxygen-bridged bonds among the aromatic structural units of lignin make it possible to obtain chemicals directly. A novel Co/C@N catalyst with high activity towards hydrogenolysis of lignin-derived aryl ethers was synthesized according to the pyrolysis process of a predesigned ZIF-67. According to the results of characterization by powder X-ray diffraction (XRD), N-2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), Co was reduced by the carbonized organic linker of ZIF-67, and N was doped into the carbon skeleton of the catalyst. The effects of holding time, temperature, and initial H-2 pressure on the catalytic performance of Co/C@N were evaluated in the selective hydrogenolysis of benzyl phenyl ether (BPE). BPE was completely converted and the selectivity of monomer reached to 98.2% under optimized reaction conditions. The C-alk-O bond in BPE was first dissociated to form toluene and phenol, and then phenol was rapidly hydrogenated to form cyclohexanol. Furthermore, the Co/C@N catalyst shows high activity for hydroprocessing and selective cleavage of other lignin-derived aryl ethers, including phenylethyl phenyl, diphenyl ether, dibenzyl ether, dinaphthalene ether, guaiacol, anisole and veratrole. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Enzymatic production of biodiesel using lipase catalyst and testing of an unmodified compression ignition engine using its blends with diesel
    The exploration for alternative fuels was prompted by increasing environmental concerns, rising conventional fuel prices and fossil fuel depletion. The improved potential of waste cooking oil makes it desirable for its utilization for biodiesel production. In the present study, enzymatic transesterification of waste cooking oil (WCO) is done using lipase enzyme to produce waste cooking oil methyl ester (WCOME) and three different test blends were used namely, Diesel+20% of WCOME, Diesel+40% of WCOME, and Diesel+60% of WCOME. After several trials the optimum reaction factors found to be methanol as the alcohol, 1.5% enzyme concentration (by weight of WCO), 3:1 M ratio and 4 h reaction time. The performance and engine characteristics like as brake specific fuel consumption, brake thermal efficiency, and the emissions of CO, HC, and NOx were analyzed in unmodified compression ignition engine. Test results revealed that the blend with lower biodiesel content performed well in the engine with lowered CO, HC and NOx emissions. But with the higher biodiesel concentrations, there was a considerable increase in the emission spectrum. Overall, Diesel+20% of WCOME and diesel+40% of WCOME blends resulted in improved performance with minimized emissions and can be utilized in an unmodified DI diesel engine. (C) 2019 Elsevier Ltd. All rights reserved.
  • [期刊] Modeling a novel combined solid oxide electrolysis cell (SOEC) - Biomass gasification renewable methanol production system
    Chemical energy storage in the form of hydrogen is playing an important role in the synthesis of alternative energy carriers such as Synthetic Natural Gas (SNG), Methanol and Dimethyl ether (DME) supplementing with a carbon source. The only renewable carbon source is biomass, which is a limited resource. However, the addition of hydrogen could potentially extend the existing biomass resources. This paper describes the modeling of a novel combined Solid Oxide Electrolysis Cell (SOEC) and oxygen blown biomass gasification system using Aspen Plus. One of the advantages of using such a combined system is the use of oxygen for gasification and reforming. The comparison of reforming technologies showed that an autothermal reformer (ATR) could be an advantage since oxygen is already available from the electrolysis stack and the ATR produced syngas has a higher CO/CO2 ratio, which increases the methanol synthesis's reaction rate. ATR requires much less energy similar to 13 MW for almost complete methane conversion compared to similar to 35 MW for Steam Reforming (SR). The advantage of using inter-cooled compression upstream or downstream for such a combined process has been explained. A methanol thermal conversion efficiency of 72.08% can be achieved for gasification and SOEC combined system compared to 55.7% for an only gasifier system. (C) 2020 Elsevier Ltd. All rights reserved.
  • [期刊] Catalytic pyrolysis of chemical extraction residue from microalgae biomass
    Pyrolysis characteristics of chemical extraction microalgae residue in the presence and absence of catalysts (KCl, KOH, K2CO3, Al2O3, CaO, MgO and pyrolysis char of microalgae residue) were evaluated using a thermal analyzer and a tube furnace reactor. These catalysts can effectively improve the oil yield during microalgae residue pyrolysis. The order of the strength on increasing the oil yield was: pyrolysis char of microalgae residue > Al2O3>CaO > K2CO3>MgO > KCl > KOH. The addition of all the catalysts can effectively reduce the potential ecological risk of heavy metals in pyrolysis chars. The addition of KCl, MgO and Al2O3 can increase the content of gasoline components in pyrolysis oil. All the catalysts can reduce the content of CO2 in the pyrolysis gas, and increase the content of CO and hydrocarbon gases. KCl addition showed considerable increase in both yield and quality of pyrolysis oil and gas with a proportion of 5 wt % during microalgae residue pyrolysis. (C) 2019 Elsevier Ltd. All rights reserved.
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