Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility

Investigation of the DI Diesel Engine Performance using Ethanol-Diesel Fuel Blends

Ethanol-diesel blend is a promising candidate as a fuel for direct injection (DI) diesel engine. In this research, solubility of different compositions of ethanol-diesel blends from 2 to 15% (v/v) ethanol were tested for 20 days. Significant increases in solubility of the blends were observed after addition of 1% (v/v) n-butanol. The Kubota’s RT140 diesel engine was operated using E7B1D92 blend at several engine speeds (1,000 to 1,600 rpm). The obtained results demonstrated that, when using E7B1D92 blend at an engine speed of 1,500 rpm, the engine power and torque of the RT140 engine were increased from 8.6 PS to 10.1 PS and 4.1 kgf-m to 5.1 kgf-m compared to pure diesel fuel. However, specific consumption fuel increased when E7B1D92 blend was used during the engine test. Additionally, analysis of exhaust gas revealed a decrease in smoke density when E7B1D92 was used instead of pure diesel

Kinetic Study on Microwave-Assisted Oligomerization of 1-Decene over a HY Catalyst

A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different reaction temperatures and times. Higher reaction temperature resulted in increasing formation of dimers and trimers. The oligomerization reaction yielded 80% conversion, 54.2% dimer product, 22.3% trimer product and 3.4% heavier product at 483 K for a reaction time of 3 h. The best fit kinetic model for the dimerization reaction was formulated from an assumption of no vacant reaction sites. For the trimerization reaction, a molecule of dimer (C20) formed on the active site, interacted with a molecule of 1-decene in the bulk solution to form a molecule of trimer (C30). Apparent activation energies for the dimerization and trimerization reactions were 70.8 ± 0.8 and 83.6 ± 0.9 kJ/mol, respectively. The C13-NMR spectrum indicated that the oligomer product contained a significant portion of highly branched hydrocarbons, causing a substantial reduction in the viscosity index compared to conventional poly-alpha olefin lubricant (PAO)

Investigation of molten salts incorporated with anodic aluminum oxide as thermal energy storage fluid on heat transfer efficiency

The aim of this research is to investigate mass and heat transfer of anodic aluminum oxide in packed-bed thermocline vessel with molten salt system (5% Lithium, 20% sodium, 50% potassium and 25% calcium). According to the computational fluid dynamic simulation, the ceramic ball that is packed inside the vessel does not have a significant impact on the mass transfer of anodic aluminum oxide in the molten salt system. Heat storage performance testing was conducted in a thermocline vessel (packed-bed zone 0.7 m in length and 0.3 m diameter) and molten salt flow rate between the ranges of 0.5–0.7 m3/h. Two different molten salt systems were studied including a normal molten salt system and a molten salt system with 0.5 wt% anodic aluminum oxide. An increase in molten salt flow rate have a positive impact on heat transfer inside the vessel due to the increase in turbulence of the flow. A decrease in charging time from 3.75 h to 3.5 h was observed for molten salt with 0.5 wt% anodic aluminum oxide. A seven-cycle charge/discharge test revealed that addition of 0.5 wt% anodic aluminum oxide resulted in a smaller reduction in heat transfer efficiency and actual energy storage. Heat storage decreased from 20.42 to 19.54 MJ corresponding heat transfer efficiency of only 87 to 85% for molten salt system consisting of anodic aluminum oxide

High throughput biodiesel production from waste cooking oil over metal oxide binded with Fe2O3

This research investigated the effects of magnetic metal oxide catalysts and operating parameters on the transesterification of waste cooking oil to biodiesel in a continuous reaction setup. Ferric oxide (Fe2O3) was incorporated in alkaline oxide to provide magnetic characteristics, instead of using filters to capture catalysts within the heating zone. Biodiesel production was conducted in a packed glass tubular reactor under ultrasonication in a water bath. The reaction parameters included reaction temperature, amount of catalyst, residence time, and ultrasonic power. Three different catalysts were studied, including calcium oxide on Fe2O3, zinc oxide on Fe2O3, and magnesium oxide on Fe2O3. The results revealed that the biodiesel yield increased with increasing reaction temperature, amount of catalyst, residence time, and ultrasonic power. The optimized biodiesel yield of 94.3% was produced over calcium on Fe2O3 at 65 °C, the methanol-to-oil ratio of 11:1, the residence time of 6.2 min, and the ultrasonic power of 185 W. An increase of reaction temperature to 75 °C resulted in a decline in biodiesel yield to 91.3% due to methanol evaporation at higher temperatures. The catalytic stability was also tested at 60 °C, 6 wt% catalyst, and 185 W ultrasonic power. It was revealed that calcium oxide on Fe2O3 catalyst demonstrated superior catalytic stability with a biodiesel yield decrease of only 10% after 34 days on stream. This suggested the magnetic feature of the catalyst helped prevent leakage of the catalyst from the system. Moreover, the quality of biodiesel met the ASTM D6751 standard for transportation fuel

Simulation of mixing intensity profile for bioethanol production via two-step fermentation in an unbaffled agitator reactor

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility.This article belongs to the Special Issue Feature Papers in Bio-EnergyOffshore and Dredging Engineerin