Ethanol Mass Research Articles

Experimental study on flow condensation of mixture in a hydrophobic microchannel

The condensation flow patterns of ethanol–water mixture in a wide range of ethanol mass concentration inside a hydrophobic microchannel is experimentally studied via a high speed imaging system. The effects of channel surface wettability and ethanol concentration on flow condensation are compared and discussed. The experimental results indicate that the surface hydrophobic modification and ethanol concentration play a significant role in the flow condensation of mixture in a microchannel. The droplet condensation appears almost the whole two-phase flow region when the water steam is the main component, in which the droplet flow, droplet-streak flow, droplet-annular flow, droplet-injection flow and droplet-slug/bubble flow occur sequentially in a hydrophobic microchannel. With increasing ethanol concentration, the droplet-slug/bubble flow after droplet-injection flow disappears and is replaced by the pure slug/bubble flow. When the ethanol vapor is the main component, the droplet condensation almost disappears, and the annular-streak flow, annular flow, injection flow and slug/bubble flow appear sequentially along the flow direction. Both an increase in vapor Reynolds number and a decrease in ethanol concentration cause the injection location move toward the channel outlet. In addition, the surface hydrophobic modification introduces the droplet condensation, which is beneficial for the flow condensation heat transfer.

Human breath simulator using controlled evaporator mixer to test the performance of a breath alcohol analyzer

We constructed a human-breath simulator using an injection-type controlled evaporator mixer (CEM) available for the performance test of a breath alcohol analyzer. The simulator was designed to spray an ethanol solution to a carrier gas through a CEM nozzle and to ensure complete evaporation using a heating device in the evaporator mixer. In terms of the ethanol mass concentrations of the test gas injected from the breath simulator, the measured values through the IR type breath analyzer and the calculated ones from the gas mixture equation were analyzed. As results of the analysis, a first-degree polynomial equation was derived to determine the correlation between the calculated and measured ethanol mass concentrations in the test gas. By the Bland-Altman plot of the measured ethanol mass concentrations and the calculated ones, it was found that the agreements between two values below 1000μgl−1 were within the 95% limit of agreement, whereas the agreements between two values above 1000μgl−1 were beyond the 95% limit of agreement. These results were considered to result from the deterioration of the measurement accuracy of the breath analyzer and errors in delivery of the true concentrations in the high ethanol mass concentrations above 1000μgl−1.

A Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 1: Structure, Properties, and Performance Correlations

Passive air-breathing microbial fuel cells (MFCs) are a promising technology for energy recovery from wastewater and their performance is highly dependent on characteristics of the separator that isolates the anaerobic anode from the air-breathing cathode. The goal of the present work is to systematically study the separator characteristics and its effect on the performance of passive air-breathing flat-plate MFCs (FPMFCs). This was performed through characterization of structure, properties, and performance correlations of eight separators in Part 1 of this work. Eight commercial separators were characterized, in non-inoculated and inoculated setups, and were examined in passive air-breathing FPMFCs with different electrode spacing. The results showed a decrease in the peak power density as the oxygen and ethanol mass transfer coefficients in the separators increased, due to the increase of mixed potentials especially at smaller electrode spacing. Increasing the electrode spacing was therefore desirable for the application of diaphragms. The highest peak power density was measured using Nafion®117 with minimal electrode spacing, whereas using Nafion®117 or Celgard® with larger electrode spacing resulted in similar peak powers. Part 2 of this work focuses on numerical modelling of the FPMFCs based on mixed potential theory, implementing the experimental data from Part 1.

Ultrasound‐based, in‐line monitoring of anaerobe yeast fermentation: model, sensor design and process application

SummaryIn order to implement process analytical technology in beer manufacturing, an ultrasound‐based in‐line sensor was developed which is capable to determine sound velocity and density via the multiple reflection method. Based on a systematic study of the ternary system water–maltose–ethanol, two models were established to estimate the critical process parameters: sugar and ethanol mass fraction. The sound velocity‐based model showed unreasonable high errors although temperature variations and deviations due to dissolved CO2 were corrected. In contrast, the sound velocity–density–temperature model provided an average root mean square error of 0.53%g/g sugar and 0.26%g/g ethanol content for the main fermentation. Method, sensor and model showed the capability to capture the process signature which may be related to product and process quality.

Ion current signal and characteristics of ethanol/gasoline dual fuel HCCI combustion

Ion current (IC) is a novel and feasible method for the diagnosis of in-cylinder combustion. The improvement of IC signal quality and reliability is always a challenge before it is applied as a sensor of engine combustion. In this paper, the characteristics of homogeneous charge compression ignition (HCCI) and IC signal with ethanol/gasoline dual fuel have been presented. The results show that increased ethanol mass fraction XEtOH retards and weakens both combustion and IC signal, with extending the phase difference (ΔθIC) between start of ion current (SOIC) and CA50 (crank angle of 50% heat release). The delayed start of gasoline injection (GSOI) enhances combustion and IC signal, but the effect is declined when XEtOH increases. This result provides a balance achieving both better quality and wider misfiring diagnosis window of IC signal. The CFD simulation results present the differences between in-cylinder local and global ion concentration with different XEtOH and GSOIs. According to the spatial distribution of electrons during the combustion, delayed GSOI causes more concentrated ionization and smaller difference between local and global start of electron appearance (SOEA).

Visualization study of condensation of ethanol–water mixtures in trapezoidal microchannels

A visualization experiment is carried out to investigate the ethanol–water vapor mixtures condensation flow patterns in an array of microchannels under a wide range of concentration (2–60%). The text microchannel is a trapezoidal silicon channel with a hydraulic diameter of 165.87μm and a length of 50mm. Along the flow direction, annular, annular-streak, annular-streak-droplet, churn, injection, droplet-injection and bubble flow patterns are observed in the vapor mixtures condensation under different inlet ethanol mass concentration (60%, 31%, 20%, 6%, 4% and 2%), which is obviously different from pure steam condensation. The equivalent surface free energy differences under various vapor conditions and vapor–surface temperature differences are calculated quantitatively. The experimental results show that flow patterns are closely related to the equivalent surface free energy differences. A correlation based on the critical quality is proposed to indicate the injection two-phase flow patterns transition.

Stripping of ethanol with CO2 in bubble columns: Effects of operating conditions and modeling

Despite being well established, a major limitation remains in ethanol fermentation processes: the presence of ethanol inhibits yeast activity, affecting the cell growth rate and, consequently, the ethanol production rate. For this reason, low ethanol concentrations of around 8–9% v/v are reached at the end of the fermentation, hence requiring the consumption of a significant amount of energy for recovery of the fermentation product, while generating large amounts of vinasse. This situation requires the use of large fermentation tanks in order to achieve satisfactory ethanol production. Additionally, due to the large amount of heat generated by the fermentation processes, the temperature control of industrial fermentation tanks is a great challenge in tropical regions such as Brazil. The goal of the present study was to analyze the influence of operating variables on the performance of ethanol stripping at bench and pilot scales, using carbon dioxide as the carrier gas, and to propose a model describing the changes in ethanol mass and solution temperature during the stripping process. Bench scale experiments were conducted using a 5-L bubble column filled with 10% v/v hydroalcoholic solution, and the pilot scale experiments were performed using a 95-L column filled with industrial fermented wine without yeast. A factorial design was applied to identify the most important operating variables for the following stripping performance parameters: entrainment factor, concentration factor, and temperature reduction factor. The results showed that both temperature and entrainment factor were positively influenced by initial solution temperature and specific CO2 flow rate, and negatively affected by height-to-diameter ratio. The temperature of the carbon dioxide did not affect either of these performance parameters. The simulation results revealed that the stripping model accurately described the decreases in ethanol mass and solution temperature during the stripping operation, with good agreement between the experimental and simulated data, and errors less than 5% in most cases.

Numerical Analyses of Single-Phase Pressure Drop and Forced Convective Heat Transfer Coefficient of Water-Ethanol Mixture: An Application in Cooling of HEV Battery Module

The present numerical analyses are related to the cooling of a hybrid electric vehicle (HEV) battery module by water–ethanol mixture. The fluid is passed through a cold plate consisting of two rectangular channels of 0.01 m depth, 0.015 m width, and 0.15 m length. The battery module is represented by a heater placed below the cold plate. The single-phase pressure drop and single-phase heat transfer coefficient for water, water–ethanol mixture of mass fraction of 25%, 50%, and 75%, and ethanol are determined numerically for different heat fluxes of 10, 15, 20, and 25 kW/m2 and different Reynolds numbers 500, 1000, 1500, 2000, and 2500. To solve the Navier–Stokes equation, the pressure correction method was used and to solve the energy equation, the Lax–Wendroff explicit method is used. Numerical results obtained for water are compared with the literature correlations. The friction factor for water deviated by an average of 8.02% from the Lewis and Robertson equation. The Nusselt number for water deviated by 7.35% from the Churchill and Ozoe equation at lower Reynolds number 500 and at higher Reynolds number 2500, Nusselt number deviated by 13.68% from the Stephan equation. The results showed that the heat transfer coefficient increased with an increase in Reynolds number and heat flux. The effect of the increase in Reynolds number is more significant than the increase in heat flux. At higher ethanol mass fraction and higher Reynolds number the heat transfer coefficient increased with heat flux when compared to water. There is no significant decrease in heat transfer coefficient with an increase in ethanol mass fraction. The pressure drop increased and the heat transfer coefficient decreased with an increase in ethanol mass fraction.

Extraction of soybean oil using ethanol and mixtures with alkyl esters (biodiesel) as co-solvent: Kinetics and thermodynamics

The kinetics and thermodynamics of soybean extraction using ethanol and ethanol+alkyl esters mixtures (biodiesel) as co-solvent were investigated. The extraction parameters investigated were temperature (25, 40 and 55°C) and biodiesel to ethanol mass ratio. The extractions were carried out in batch mode at a fixed solvent to soybean mass ratio (4:1). Three different kinetic models were used to correlate the overall extraction curves, namely a first-order, second-order, and a mass transfer model based on Fick’s Law. The mass transfer model presented a mean absolute relative deviation of 4.7%, while de first and second-order models showed values around 10.1% and 4.4%, respectively. From the experimental results obtained, it was observed that higher temperatures affected positively the extraction yields. Furthermore, higher mass ratio of biodiesel to anhydrous ethanol provide higher extraction yields, at temperatures of 25 and 40°C. At 55°C, the extraction yields were not improved when adding the biodiesel as co-solvent to the anhydrous ethanol. On the other hand, using hydrated ethanol as solvent resulted in lower extraction yields, so higher amounts of biodiesel were necessary to reach the same levels of extractions performed using anhydrous ethanol. The thermodynamic analyses showed that both ΔH° and ΔS° are positive for this process, while negative values of ΔG° were found, that means the process evaluated is characterized as endothermic, irreversible and occurs spontaneously.

Experimental Study on Condensation Heat Transfer of Ethanol–Water Vapor Mixtures on Vertical Micro-tubes

The paper presents an experimental investigation of Marangoni condensation heat transfer of ethanol–water vapor mixtures on vertical micro-tubes with an outer diameter of 0.793 mm, 1.032 mm, and 1.221 mm. Experiments were performed over a wide range of ethanol mass fractions in vapor mixtures for different vapor velocities and pressures. Condensation heat transfer coefficients behaved nonlinear characteristics, increased, and then decreased with increasing vapor-to-surface temperature difference. Under the same experimental conditions, the condensation heat transfer coefficient at a 2 % ethanol mass fraction in vapor was the highest. At low ethanol mass fractions, the condensation heat transfer coefficient of the ethanol–water vapor mixture was 2 to 3 times greater than that for pure steam. The effect of vapor pressure and velocity on condensation heat transfer suggested a positive tendency on each micro-tube for all vapor mixtures with different ethanol mass fraction. Results showed that condensation heat transfer coefficients on micro-tubes with a diameter of 1.032 mm were higher than those on the other two micro-tubes, suggesting that there existed a critical diameter which gave the largest condensation heat transfer coefficient.

Airborne measurements of the atmospheric emissions from a fuel ethanol refinery

AbstractEthanol made from corn now constitutes approximately 10% of the fuel used in gasoline vehicles in the U.S. The ethanol is produced in over 200 fuel ethanol refineries across the nation. We report airborne measurements downwind from Decatur, Illinois, where the third largest fuel ethanol refinery in the U.S. is located. Estimated emissions are compared with the total point source emissions in Decatur according to the 2011 National Emissions Inventory (NEI‐2011), in which the fuel ethanol refinery represents 68.0% of sulfur dioxide (SO2), 50.5% of nitrogen oxides (NOx = NO + NO2), 67.2% of volatile organic compounds (VOCs), and 95.9% of ethanol emissions. Emissions of SO2 and NOx from Decatur agreed with NEI‐2011, but emissions of several VOCs were underestimated by factors of 5 (total VOCs) to 30 (ethanol). By combining the NEI‐2011 with fuel ethanol production numbers from the Renewable Fuels Association, we calculate emission intensities, defined as the emissions per ethanol mass produced. Emission intensities of SO2 and NOx are higher for plants that use coal as an energy source, including the refinery in Decatur. By comparing with fuel‐based emission factors, we find that fuel ethanol refineries have lower NOx, similar VOC, and higher SO2 emissions than from the use of this fuel in vehicles. The VOC emissions from refining could be higher than from vehicles, if the underestimated emissions in NEI‐2011 downwind from Decatur extend to other fuel ethanol refineries. Finally, chemical transformations of the emissions from Decatur were observed, including formation of new particles, nitric acid, peroxyacyl nitrates, aldehydes, ozone, and sulfate aerosol.

Mechanistic insight into ultrasound induced enhancement of simultaneous saccharification and fermentation of Parthenium hysterophorus for ethanol production

This paper presents investigations into mechanism of ultrasound assisted bioethanol synthesis using Parthenium hysterophorus biomass through simultaneous saccharification and fermentation (SSF) mode. Approach of coupling experimental results to mathematical model for SSF using Genetic Algorithm based optimization has been adopted. Comparison of model parameters for experiments with mechanical shaking and sonication (10% duty cycle) give an interesting mechanistic account of influence of ultrasound on SSF system. A 4-fold rise in ethanol and cell mass productivity is seen with ultrasound. The analysis reveals following facets of influence of ultrasound on SSF: increase in Monod constant for glucose for cell growth, maximal specific growth rate and inhibition constant of cell growth by glucose and reduction in specific cell death rate. Values of inhibition constant of cell growth by ethanol (K3E), and constants for growth associated (a) and non-growth associated (b) ethanol production remained unaltered with sonication. Beneficial effects of ultrasound are attributed to enhanced cellulose hydrolysis, enhanced trans-membrane transport of substrate and products as well as dilution of the toxic substances due to micro-convection induced by ultrasound. Intrinsic physiological functioning of cells remained unaffected by ultrasound as indicated by unaltered values of K3E, a and b.

Ultrasound enhanced ethanol production from Parthenium hysterophorus: A mechanistic investigation

This study presents mechanistic investigations in ultrasound-assisted bioethanol fermentation using Parthenium hysterophorus biomass. Ultrasound (35kHz, 10% duty cycle) has been used for sonication. Experimental results were fitted to mathematical model; the kinetic and physiological parameters in the model were obtained using Genetic Algorithm (GA) based optimization. In control experiments (mechanical shaking), maximum ethanol titer of 10.93g/L and cell mass concentration of 5.26g/L was obtained after 18h. In test experiments (mechanical shaking and intermittent sonication), ethanol titer of 12.14g/L and cell mass concentration of 5.7g/L was obtained in 10h. This indicated ∼2× enhanced productivity of ethanol and cell mass with sonication. Trends in model parameters obtained after fitting of model to experimental data essentially revealed that beneficial influence of ultrasound on fermentation is a manifestation of enhanced trans-membrane transportation and dilution of toxic substances due to strong micro-convection induced by ultrasound.

LES of the Sydney piloted spray flame series with the PFGM/ATF approach and different sub-filter models

Detailed numerical investigations of the Sydney spray flame series [1] are presented for ethanol flames referred to as “EtF3, EtF6 and EtF8”, which feature identical ethanol mass flow rates but different carrier gas mass flow rates. Large eddy simulations (LES) are performed, where the gaseous and liquid phases are modeled by an Eulerian/Lagrangian approach. The turbulent sub-filter stresses (sgs) are modeled with Nicoud’s sigma model [2] on grids with two different resolutions. Combustion is modeled with the premixed flamelet generated manifold approach (PFGM), which is combined with the artificially thickened flame (ATF) method. The sub-filter distributions of the control variables are modeled with (a) a β function (β-fdf) and (b) a top-hat function (TH). First, the influence of the variance in the mixture fraction and reaction progress variable is investigated separately, where the variances are either determined from an algebraic model or a transport equation model. Subsequently, the TH model is used to account for the joint impact of Z and Yp. The results are compared against the experimental measurements and reference simulations without sub-filter model. The particle statistics are in good agreement with the experimental data. The variances predicted by the two algebraic models are quite similar, whereas the transport equation model predicts variances which are one order of magnitude higher. The results obtained with the TH and the β-fdf model are comparable. It is found that the impact of the sgs models for the mixture fraction and the progress variable increases with an increasing carrier gas mass flow rate.

Improved conversion efficiencies for n-fatty acid reduction to primary alcohols by the solventogenic acetogen "Clostridium ragsdalei".

"Clostridium ragsdalei" is an acetogen that ferments synthesis gas (syngas, predominantly H2:CO2:CO) to ethanol, acetate, and cell mass. Previous research showed that C. ragsdalei could also convert propionic acid to 1-propanol and butyric acid to 1-butanol at conversion efficiencies of 72.3 and 21.0 percent, respectively. Our research showed that C. ragsdalei can also reduce pentanoic and hexanoic acid to the corresponding primary alcohols. This reduction occurred independently of growth in an optimized medium with headspace gas exchange (vented and gassed with CO) every 48 h. Under these conditions, conversion efficiencies increased to 97 and 100 % for propionic and butyric acid, respectively. The conversion efficiencies for pentanoic and hexanoic acid to 1-pentanol and 1-hexanol, respectively, were 82 and 62 %. C. ragsdalei also reduced acetone to 2-propanol at a conversion efficiency of 100 %. Further, we showed that C. ragsdalei uses an aldehyde oxidoreductase-like enzyme to reduce n-fatty acids to the aldehyde intermediates in a reaction that requires ferredoxin and exogenous CO.

Continuous catalyst-free production of esters from Jatropha curcas L. oil under supercritical ethanol

In the present study, the transesterification of Jatropha oil in a continuous catalyst-free process using supercritical ethanol was investigated. Experiments were performed in a packed-bed tubular reactor by studying the effect on the reaction of temperature, pressure, water and cosolvent (n-hexane) concentrations, keeping the oil:ethanol mass ratio fixed at 1:1 for different residence times. The results demonstrated that temperature and pressure had a positive effect on fatty acid ethyl ester (FAEE) production and it was observed that the free fatty acids present in vegetable oil promote faster reaction kinetics due to simultaneous esterification and transesterification reactions. The addition of water and a cosolvent increased the FAEE yields at 573 K and 20 MPa. Within the experimental ranges investigated, water and the cosolvent decreased the decomposition of fatty acids. Appreciable reaction yields (~90 wt%) were achieved at 573 K, 20 MPa, with an oil:ethanol mass ratio of 1:1 and 10 wt% water.

Bubble departure diameter in nucleate pool boiling at saturation: Pure liquids and binary mixtures

Bubble dynamics is the most important sub-phenomenon, which basically affects the nucleate pool boiling heat transfer coefficient. Previous investigations state that the effect of physical properties of liquid and vapor phases on bubble departure diameter are often conflicting. In this article, extensive new experimental data at atmospheric pressure are presented for bubble departure diameters during saturated pool boiling for pure water, ethanol and various binary mixtures, including ethanol/water, NaCl/water and Na2SO4/water over a wide range of concentrations. For all test fluids, experimental results show that bubble diameter increases with increasing heat flux. Also, experimental results show that bubble detachment diameter increases with increasing electrolyte concentration and decreases with increasing ethanol mass fraction. A new model for the prediction of vapor bubble departure diameter, based on Buckingham theory, in nucleate boiling is proposed, which predicts the experimental data with a satisfactory accuracy.

Effect of Additives in the Reaction Medium on Noncatalytic Ester Production from Used Frying Oil with Supercritical Ethanol

In this study, the noncatalytic production of ethyl esters from used frying oil (UFO) in a continuous process was evaluated under supercritical conditions. Experiments were performed with the objective of evaluating the effect of the addition of water, a co-solvent (n-hexane), and ethyl esters to the reaction medium, applying different temperatures and keeping the oil:ethanol mass ratio (1:1), pressure (20 MPa), and residence time (40 min) fixed. The results demonstrated that the formation of fatty acid ethyl esters (FAEE) is favored at higher temperatures. The addition of 5 wt % water increased the yield, while no significant effect (p > 0.05) was noted with the addition of 10 wt % water. The addition of cosolvent and ethyl esters in the range investigated plays a vital role in maximizing the FAEE yields for most conditions studied. The presence of water and cosolvent reduced the degree of fatty acids decomposition, while the addition of ethyl esters increased this parameter. The effect of the residence ...

Pelletisation of canola meal by extrusion–spheronisation for ethanol dehydration

Canola meal has been previously demonstrated to be an attractive biomaterial for dehydrating wet ethanol vapours in bioethanol manufacture. Extrusion–spheronisation was employed to prepare reasonably spherical pellets of canola meal for use in dehydration units. Canola meal pastes were prepared at water volume fractions of 57–70% and extruded through single and multi-holed dies with diameters 2, 3.5 and 4.5 mm. The pressure required to extrude the pastes, size and shape distribution of pellets and strength of dried pellets were measured. Formulations with a water volume fraction of 70% gave low extrusion pressures and highest pellet strength. Die land diameters of 2 mm gave the best combination of specific surface area, size and shape distribution, packing density and ethanol adsorption. Dehydration testing confirmed that the canola meal pellets could dehydrate water/ethanol vapour from an ethanol mass fraction of 92.5% (below the azeotrope at 1 bara) to 99%. The equilibrium water loading of 47.3 mg water per g adsorbent is larger than other biomass-based adsorbents reported for this application.

The effect of ethanol–diesel–biodiesel blends on combustion, performance and emissions of a direct injection diesel engine

The article presents the test results of a four-stroke, four-cylinder, naturally aspirated, DI 60kW diesel engine operating on diesel fuel (DF) and its 5vol% (E5), 10vol% (E10), and 15vol% (E15) blends with anhydrous (99.8%) ethanol (E). An additional ethanol–diesel–biodiesel blend E15B was prepared by adding the 15vol% of ethanol and 5vol% of biodiesel (B) to diesel fuel (80vol%). The purpose of the research was to examine the influence of the ethanol and RME addition to diesel fuel on start of injection, autoignition delay, combustion and maximum heat release rate, engine performance efficiency and emissions of the exhaust when operating over a wide range of loads and speeds. The test results were analysed and compared with a base diesel engine running at the same air–fuel ratios of λ=5.5, 3.0 and 1.5 corresponding to light, medium and high loads. The same air–fuel ratios predict that the energy content delivered per each engine cycle will be almost the same for various ethanol–diesel–biodiesel blends that eliminate some side effects and improve analyses of the test results.A new approach revealed an important role of the fuel bound oxygen, which reflects changes of the autoignition delay more predictably than the cetane number does. The influence of the fuel oxygen on maximum heat release rate, maximum combustion pressure, NOx, CO emissions and smoke opacity of the exhaust is highly dependent on the air–fuel ratio and engine speed. Fuelled with blend E15B the diesel engine develops the brake thermal efficiency of 0.362, i.e. the same as a straight diesel running on slightly richer air–fuel mixture λ=1.5 at rated 2200rpm speed. Adding of the ethanol to diesel fuel reduces the NOx and the HC emissions for richer combustible mixtures whereas the influence of a higher ethanol mass content on CO emissions and smoke opacity depends on the air–fuel ratio and engine speed.