Academic literature on the topic 'Vapor mole fraction'
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Journal articles on the topic "Vapor mole fraction"
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Li, Xiao, and Yun Ren Qiu. "Vapor-Liquid Equilibrium for Binary Systems of Methyl Ethyl Ketone and Methyl Isobutyl Ketone." Advanced Materials Research 550-553 (July 2012): 2616–20. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2616.
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Atmospheric vapor-liquid equilibrium data of methyl ethyl ketone (MEK) - methyl isobutyl ketone (MIBK) were measured using an improved Rose still and were used to recover the parameters of NRTL and UNIQUAC models. The results show that the simulated results agree well with the experimental data. The mean temperature variation is 0.14 °C and the mean mole fraction variation is 0.0023 using UNIQUAC model while the mean temperature variation is 0.17 °C and the mean mole fraction variation is 0.0025 using NRTL model. Both models can be used to calculate the atmospheric vapor-liquid equilibrium data of MEK - MIBK.
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Okajima, Idzumi, Kaichi Ito, Yusuke Aoki, Chang Yi Kong, and Takeshi Sako. "Extraction of Rice Bran Oil Using CO2-Expanded Hexane in the Two-Phase Region." Energies 15, no. 7 (April 2, 2022): 2594. http://dx.doi.org/10.3390/en15072594.
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The performance of CO2-expanded hexane in the vapor-liquid two-phase region was examined to extract phosphorus-free bio-oil from rice bran. Previously, it was found that in the uniform liquid phase region, it is difficult to maintain the phosphorus concentration at a stable and low level when the CO2 mole fraction changed slightly. To overcome this issue, the dependences of the phosphorus and free fatty acid concentrations, the oil solubility, and the oil yield on the CO2 mole fraction in the CO2-expanded hexane were measured at 25 °C, 5.1–5.2 MPa, and at a CO2 mole fraction of 0.88–0.94 in the two-phase region. Thus, a relatively constant phosphorus concentration of <10 ppm was maintained in the extracted oil, which was ~1/50 of that in the oil extracted by hexane, thereby satisfying the European unified standard for biodiesel fuel. Furthermore, a high oil yield exceeding that of hexane extraction was maintained over all CO2 mole fractions. Moreover, the oil solubility in the CO2-expanded hexane decreased linearly with the CO2 mole fraction, and so this factor represented the oil-dissolving power of the extractant more accurately than the oil yield used previously. The free fatty acid concentration was 83% of that extracted by hexane.
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Zhao, Weilong, Hao Wu, Jing Wen, Xin Guo, Yongsheng Zhang, and Ruirui Wang. "Simulation Study on the Influence of Gas Mole Fraction and Aqueous Activity under Phase Equilibrium." Processes 7, no. 2 (January 22, 2019): 58. http://dx.doi.org/10.3390/pr7020058.
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This work explored the influence of gas mole fraction and activity in aqueous phase while predicting phase equilibrium conditions. In pure gas systems, such as CH4, CO2, N2 and O2, the gas mole fraction in aqueous phase as one of phase equilibrium conditions was proposed, and a simplified correlation of the gas mole fraction was established. The gas mole fraction threshold maintaining three-phase equilibrium was obtained by phase equilibrium data regression. The UNIFAC model, the predictive Soave-Redlich-Kwong equation and the Chen-Guo model were used to calculate aqueous phase activity, the fugacity of gas and hydrate phase, respectively. It showed that the predicted phase equilibrium pressures are in good agreement with published phase equilibrium experiment data, and the percentage of Absolute Average Deviation Pressures are given. The water activity, gas mole fraction in aqueous phase and the fugacity coefficient in vapor phase are discussed.
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Boylan, P., D. Helmig, and J. H. Park. "Characterization and mitigation of water vapor effects in the measurement of ozone by chemiluminescence with nitric oxide." Atmospheric Measurement Techniques Discussions 6, no. 5 (October 29, 2013): 9263–95. http://dx.doi.org/10.5194/amtd-6-9263-2013.
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Abstract. Laboratory experiments were conducted to investigate the effects of water vapor on the reaction of nitric oxide with ozone in a chemiluminescence instrument used for fast response and high sensitivity detection of atmospheric ozone. Water vapor was introduced into a constant level ozone standard and both ozone and water vapor signals were recorded at 10 Hz. The presence of water vapor was found to reduce, i.e. quench the ozone signal. A correction factor was determined to be 4.15 ± 0.14 × 10−3, which corresponds to a 4.15% increase in the measured ozone signal per 10 mmol mol−1 co-sampled water vapor. An ozone-inert water vapor permeable membrane (Nafion dryer) was installed in the sampling line and was shown to remove the bulk of the water vapor mole fraction in the sample air. At water vapor mole fractions above 25 mmol mol−1, the Nafion dryer removed over 75% of the water vapor in the sample. This reduced the ozone signal correction from over 11% to less than 2.5%. The Nafion dryer was highly effective at reducing the fast fluctuations of the water vapor signal (more than 97%) while leaving the ozone signal unaffected, which is a crucial improvement for minimizing the interference of water vapor fluxes on the ozone flux determination by the eddy covariance technique.
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Rivera, Abdiel, Anas Mazady, and Mehdi Anwar. "ZnMgO/ZnO Core-Shell Structures for Gas Sensing." International Journal of High Speed Electronics and Systems 24, no. 03n04 (September 2015): 1550010. http://dx.doi.org/10.1142/s012915641550010x.
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Co-axial Zn1−xMgxO core, ZnO shell structures were grown using metal organic chemical vapor deposition (MOCVD), with Mg mole fractions of 2, 5 and 10%. The co-axial core shell structure, with the respective Mg concentration is verified using scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS). The response times (ṟise time and fall time) of the devices, after being exposed to methanol, varied with Mg mole fraction at the core, r-0.17s and, f-0.37s & f-0.48s for 2% Mg, r-0.81s and, f-5.98s & f-0.89s for 5% Mg and r-0.33s and f-0.13s for 10% Mg. The sensitivity of the devices at room temperature increased with the increment of Mg mole fraction at the core, 25%, 48% and 50% with Mg concentration of 0.02, 0.05 and 0.1, respectively, under high concentration of methanol. The estimated activation energy, corresponds to doubly charged oxygen vacancy (Vo2+).
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Fan, Q. H., H. Y. Li, L. X. Jia, Q. H. Fan, Yi Min Shao, and X. H. Zhan. "Selection of Mixed Refrigerant for CBM Liquefaction System and its Optimization Analysis." Advanced Materials Research 443-444 (January 2012): 193–97. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.193.
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In the mixed refrigerant cycle, the key technology is the choosing of the mixed refrigerant and its optimization mixture ratio. Based on a small-scale CBM liquefaction system LNG5, which the capacity is 5 cube meters LNG per day, the numerical simulation and optimization for the LNG5 are carried out. It provides the composition of the mixed refrigerant. It analyzes the effects of mixed refrigerant components on the temperature difference of the heat exchangers and the vapor fraction of the key nodes. The analysis results show that a reasonable mixture ratio of mixed refrigerant is given, such as CH4 mole fraction being 41.8% ～ 44.3%, C2H6 mole fraction being 40.8% ～ 42.2%, C5H12 molar fraction being 14.3% ～ 16%, and N2 mole fraction being 1.5% ～ 3.3%. The results provide guidelines for the design of the small-scale CBM liquefaction device, and for the application and commissioning of CBM liquefaction plant in China.
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Buchholz, Bernhard, and Volker Ebert. "Absolute, pressure-dependent validation of a calibration-free, airborne laser hygrometer transfer standard (SEALDH-II) from 5 to 1200 ppmv using a metrological humidity generator." Atmospheric Measurement Techniques 11, no. 1 (January 23, 2018): 459–71. http://dx.doi.org/10.5194/amt-11-459-2018.
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Abstract. Highly accurate water vapor measurements are indispensable for understanding a variety of scientific questions as well as industrial processes. While in metrology water vapor concentrations can be defined, generated, and measured with relative uncertainties in the single percentage range, field-deployable airborne instruments deviate even under quasistatic laboratory conditions up to 10–20 %. The novel SEALDH-II hygrometer, a calibration-free, tuneable diode laser spectrometer, bridges this gap by implementing a new holistic concept to achieve higher accuracy levels in the field. We present in this paper the absolute validation of SEALDH-II at a traceable humidity generator during 23 days of permanent operation at 15 different H2O mole fraction levels between 5 and 1200 ppmv. At each mole fraction level, we studied the pressure dependence at six different gas pressures between 65 and 950 hPa. Further, we describe the setup for this metrological validation, the challenges to overcome when assessing water vapor measurements on a high accuracy level, and the comparison results. With this validation, SEALDH-II is the first airborne, metrologically validated humidity transfer standard which links several scientific airborne and laboratory measurement campaigns to the international metrological water vapor scale.
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Shi, Xiu Min, and Min Wang. "Isobaric Vapor-Liquid Equilibrium for Ethyl Acetate-Isopropanol-1-Octyl-3-Methylimidazolium Tetrafluoroborate." Advanced Materials Research 641-642 (January 2013): 160–64. http://dx.doi.org/10.4028/www.scientific.net/amr.641-642.160.
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Abstract: In order to study the possibility of separating ethyl acetate and isopropanol by extractive distillation with ILs as an entrainer. Isobaric vapor-liquid equilibrium data for ethyl acetate + isopropanol+1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM]BF4) ternary system at 101.32 kPa were determined using a recirculating still. The results showed that the ionic liquid (IL) studied produced a notable salting-out effect, which enhanced the relative volatility of ethyl acetate to isopropanol and eliminated the azeotrope when the mole fraction of IL in the liquid phase was greater than 0.10. Therefore, [OMIM]BF4 can be used as the extraction agent of extractive distillation for ethyl acetate + isopropanol systerm, the suitable mole fraction of [OMIM]BF4 is about 20%. The experimental data were correlated with the NRTL model, the correlated results agreed well with the experimental data.
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Zhao, Chen Lu, Wei Qiu Huang, Ying Xia Wang, and Li Shi. "Experimental Study on Adsorption of Gasoline Vapor on Activated Carbon at High Concentration." Advanced Materials Research 807-809 (September 2013): 549–52. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.549.
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Dynamic and thermodynamic characteristics of gasoline vapor adsorption at 0.3 mol/mol on different activated carbons (ACs) were investigated. The adsorption capacities of AC1 and AC3 were 0.295 g/g and 0.189 g/g at 20 oC, and 0.284 g/g and 0.165 g/g at 30 °C, respectively. Bed temperature rise was up to 50°C to 60°C in the adsorption of gasoline vapor at 0.3 mol/mol.The heat effect formula for high concentration vapor adsorption was deduced to evaluate the relationship of the adsorption capacity of the activated carbons, the mole fraction of the inlet gasoline vapor, the recovery efficiency of the gasoline vapor with the temperature rise.
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Chu, C. Judith, Mark P. D'Evelyn, Robert H. Hauge, and John L. Margrave. "Mechanism of diamond film growth by hot-filament CVD: Carbon-13 studies." Journal of Materials Research 5, no. 11 (November 1990): 2405–13. http://dx.doi.org/10.1557/jmr.1990.2405.
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Mixed carbon-12/carbon-13 diamond films were synthesized by hot-filament chemical vapor deposition, using mixtures of 13CH4 and 12CH4 or 12C2H2 in H2. The first-order Raman peak at 1332 cm−1 for 12C-diamond was found to shift by 50 cm−1 to 1282 cm−1 for pure 13C-diamond. For mixed-isotope films, the Raman peak frequency shifts linearly between these values as a function of the 13C mole fraction. The mechanism of diamond film growth by hot-filament CVD has been investigated by growth from mixtures of 13CH4 and 12C2H2, using the shifted Raman frequency to determine the relative incorporation rates of 13C and 12C into the film. The 13C mole fraction in the film agrees closely with the 13C mole fraction inferred for the methyl radical but differs substantially from that of acetylene, indicating that the methyl radical is the dominant growth precursor under the conditions studied.
Book chapters on the topic "Vapor mole fraction"
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Oriakhi, Christopher O. "Ideal Solutions and Colligative Properties." In Chemistry in Quantitative Language. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195367997.003.0019.
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Colligative properties of solutions are those that depend only on the number of solute particles (molecules or ions) in the solution rather than on their chemical or physical properties. The colligative properties that can be measured experimentally include: • Vapor pressure depression • Boiling point elevation • Freezing point depression • Osmotic pressure Noncolligative properties, on the other hand, depend on the identity of the dissolved species and the solvent. Examples include solubility, surface tension, and viscosity. The addition of a solute to a solvent typically causes the vapor pressure of the solvent (above the resulting solution) to be lower than the vapor pressure above the pure solvent. As the concentration of the solute in the solution changes, so does the vapor pressure of the solvent above a solution. The vapor pressure of a solution of a nonvolatile solute is always lower than that of the pure solvent. For example, an aqueous solution of NaCl has a lower vapor pressure than pure water at the same temperature. The addition of solute to a pure solvent depresses the vapor pressure of the solvent. This observation, first made by Raoult, is now commonly known as Raoult’s law. The law states that the lowering of vapor pressure of a solution containing non-volatile solute is proportional to the mole fraction of the solute.
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Anderson, Greg M., and David A. Crerar. "Standard States." In Thermodynamics in Geochemistry. Oxford University Press, 1993. http://dx.doi.org/10.1093/oso/9780195064643.003.0016.
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At this point we have introduced the activity as a ratio of fugacities (Chapter 11). The fugacity of a constituent, in turn, we saw was a quantity very much like a vapor pressure or partial pressure, which is directly linked to the Gibbs free energy of that constituent, such that a ratio of fugacities leads directly to a difference in free energies. The fugacity was introduced as a means of dealing with gases and gaseous solutions, and it is measured by measuring gas volumes or densities. Nevertheless, there is nothing restricting its use to gaseous constituents, and we suggested that it is very useful to regard the fugacity as a state variable; as a property of any constituent of any system, solid, liquid, or gas, whether equilibrated with a gas or not, and whether measurable or not. This leads to the easiest approach to understanding activities. The activity of a constituent is the ratio of the fugacity of that constituent to its fugacity in some other state, which we called a reference state. We then showed through consideration of the Lewis Fugacity Rule, which is an extension of Dalton's Law, that for ideal solutions of condensed phases, the activity of a constituent equals its mole fraction, if the reference state is the pure constituent at the same P and T. Deviations from ideal behaviour are then conveniently handled by introducing Henryan and Raoultian activity coefficients. The utility of these relations would be quite sufficient for retaining the activity in our collection of thermodynamic parameters, but in fact the activity can be applied to a much wider range of conditions, simply by varying the choice of reference state. We now examine the various possible choices of this reference state, and the resulting equations and applications. In the most general sense, the fugacity and activity concepts satisfy the need to relate system compositions to free energy changes. That a single parameter, the activity, can do this for essentially any system is a tribute to its tremendous versatility.
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Szeinuk, Jaime, and Rafael E. de la Hoz. "Occupational Chronic Obstructive Pulmonary Disease." In Modern Occupational Diseases Diagnosis, Epidemiology, Management and Prevention, 104–27. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815049138122010010.
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Chronic Obstructive Pulmonary Disease (COPD) is a clinical syndrome defined as non- or incompletely reversible airflow obstruction associated with persistent lower respiratory symptoms such as dyspnea, cough, and excessive sputum production. The present definition probably includes more than one disease. Despite being largely preventable, COPD is often a disabling disease with accelerated longitudinal lung function loss and systemic comorbidities and is presently the third leading cause of death and one of the most important health care expenditures worldwide. While most cases are unquestionably related to tobacco smoking, it has long been suspected and is also now fairly well established that occupational and environmental exposures, as well as a variety of other factors, contribute to its causation. Most recent estimates place the fraction of COPD causation by occupational exposures at ~15% and ~30% overall and among nonsmokers, respectively. The disease occurs in workers exposed to vapors, gases, dust, and fumes at their longestheld job, and in several occupations that include miners, agricultural, cotton/textile, and construction workers, food, drink, and tobacco processors, and bus drivers, among others. There is evidence of an additive effect of occupational exposures and cigarette smoking. There is presently no evidence that treatments differ from those in widely accepted guidelines, except for the occupational interventions for primary, secondary, and tertiary prevention discussed throughout this book. This is in large part due to treatment trials having required a fairly heavy smoking history and disregarded patients’ occupations. Improved appraisal of the etiological contribution of occupational exposures should lead to progress towards disease elimination.
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Tinker, Peter B., and Peter Nye. "Solute Interchange between Solid, Liquid, and Gas Phases in the Soil." In Solute Movement in the Rhizosphere. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195124927.003.0007.
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We noted in chapter 1 that the concentration of solute in the soil solution is buffered by solute adsorbed on the soil surfaces. We also show in chapter 4 that the overall mobility of ions is related to their amounts and mobilities in the solid and solution. In this chapter, we focus on the soil solution concentration, primarily to show how the factors controlling it can be incorporated in models of the growth of crops and the leaching of nutrients or pollutants, such as those described in chapters 10 and 11. We examine the general principles governing the interchange of solutes between all phases in the soil, dealing first with inorganic ions, especially plant nutrients and heavy metals; and later with organic solutes, including biocides, which may also occur in the vapour phase. We also consider the reactions between metal ions and other organic or inorganic ions in solution to form complexes, such as CuOH+. The method of displacing the pore solution from a column of soil with ethanol, introduced by Ischtscherikow (1907), has been examined by Moss (1963, 1969). He found, in accord with theory (section 3.1.3), that the activity ratios (K)/(Ca + Mg)1/2 and (K)/(Ca)1/2 determined in the displaced solutions remained constant over considerable changes in soil moisture level to the point of saturation. He also found that the activity ratio (K)/(Ca + Mg)1/2 in the extracts from a wide range of soils agreed well with the activity ratio determined by the null point method of Beckett & Craig (1964). In this method, the soil is shaken with dilute CaCl2 solution containing graded amounts of potassium, and the activity ratio at which the soil does not gain or lose potassium to the solution is determined. Ethanol appears to displace solution from the fine as well as the coarse pores, and successive fractions, devoid of alcohol, have the same composition. For small samples of soil, it is more convenient to add a heavy liquid that is immiscible with water, and extract the solution by centrifuging (Kinniburgh & Miles 1983). Suction methods are useful for following changes in composition of moist soils. They should be used with care since they change the pressure of CO2 and hence the concentration of the bicarbonate ion.
Conference papers on the topic "Vapor mole fraction"
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Wang, Kai, Edgar Molina, Ghazal Dehghani, Ben Xu, Peiwen Li, Qing Hao, Pierre Lucas, Mohamad H. Kassaee, Sheldon M. Jeter, and Amyn S. Teja. "Experimental Investigation to the Properties of Eutectic Salts by NaCl-KCl-ZnCl2 for Application as High Temperature Heat Transfer Fluids." In ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6578.
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A group of eutectic ternary halide salts were surveyed and studied for the objective of developing a high temperature heat transfer fluid with a freezing point below 250°C and a low vapor pressure, below 1.0 atm, at temperatures up to 800°C. The studied salts include: 1) NaCl-KCl-ZnCl2 with a mole fractions of 18.6%-21.9%-59.5% and a melting point of tm=213°C; 2) NaCl-KCl-ZnCl2 with a mole fraction of 13.4%-33.7%-52.9% and a melting point of tm=204°C; and 3) NaCl-KCl-ZnCl2 with mole fraction of 13.8%-41.9%-44.3% and a melting point of tm=229 °C. Vapor pressures of these salts at different temperatures were experimentally obtained using an in-house developed test facility. The results show that vapor pressures of all the three eutectic molten salts are below 1.0 atm at a temperature of 800 °C. The salt of ZnCl2-KCl-NaCl in mole faction of 44.3%-41.9%-13.8% has lowest vapor pressure which is only about 1.0 atm even at a temperature of 900 °C. Viscosities of these salts were measured in the temperature range from after melting to 850°C. At low temperatures near their melting points of the salts, the viscosities are about 16 × 10−3Pa s, while at high temperatures above 700°C the viscosities are around 4 × 10−3Pa s, which is satisfactorily low to serve as heat transfer fluid for circulation in a CSP system. Both the vapor pressure and the viscosities of the studied three eutectic salts demonstrated satisfaction to serve as high temperature heat transfer fluids. Other thermal and transport properties of these salts are expected to be reported in the future for screening out a satisfactory high temperature heat transfer fluid.
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Chichibu, Shigefusa F., Youichi Ishikawa, Kentaro Furusawa, Akira Uedono, Hideto Miyake, and Kazumasa Hiramatsu. "Spatio-time-resolved cathodoluminescence study on high AlN mole fraction AlxGa1−xN structures grown by metalorganic vapor phase epitaxy." In 2016 Compound Semiconductor Week (CSW) [Includes 28th International Conference on Indium Phosphide & Related Materials (IPRM) & 43rd International Symposium on Compound Semiconductors (ISCS)]. IEEE, 2016. http://dx.doi.org/10.1109/iciprm.2016.7528769.
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Dover, Selina C., Ambarish R. Dahale, Babak Shotorban, Shankar Mahalingam, and David R. Weise. "Influence of Vegetation Moisture on Combustion of Pyrolysis Gases in Wildland Fires." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62082.
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Since wildland fires occur in living vegetation, the fuel moisture content must be considered in order to correctly predict the behavior of the fire. One facet of combustion of pyrolysis gases that has not been considered in previous research is the effect of moisture on the combustion process. This effect is investigated by using CHEMKIN software to study an opposed diffusion flame model for three pyrolysis fuels relevant to wildfires. The effect of moisture on flame structure is investigated by varying the mole fraction of water vapor in the fuels, with air as oxidizer. In all cases, the flame extinguishes when the water mole fraction is between 0.55 and 0.65. O2 and H are the only components that exhibit a significant change in concentration under these conditions.
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Nie, Jianhu, Yitung Chen, Bunsen Wong, and Lloyd C. Brown. "Numerical Modeling of Vapor Condensation During Cadmium Quenching Process in a Solar Receiver." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90382.
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Cadmium quencher is an important equipment for the high efficiency generation of hydrogen fuel using solar thermochemical splitting of water. In order to effectively guide the design of solar decomposer and vapor quencher, it is of critical importance to understand the mechanisms of transport phenomena inside them. The mixture model was selected for modeling the multiphase flow, and the two-equation RNG k-ε model was used to model the turbulent flow and heat transfer. Numerical results showed that flowrate of the quencher air directly influences the velocity, temperature and mole fraction of cadmium vapor inside the decomposer and quencher. The developed CFD model can be used to guide the design of efficient solar receiver and cadmium decomposer/quencher.
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Park, Inmyong, Sehwan In, and Sangkwon Jeong. "Flow Boiling Heat Transfer Characteristic of Ternary Mixture in a Micro-Channel." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44079.
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This paper describes the flow boiling heat transfer of R123/R134a/R22 mixture in a single round micro-channel with 0.19 mm ID. The flow boiling heat transfer coefficients were measured for ternary mixture (R123/R134a/R22 mole fraction: 0.194/0.62/0.186) at various experimental conditions: mass velocities (314, 392, 470 kg/m2-s), heat fluxes (10, 15, 20 kW/m2) and vapor qualities (0.2–0.8). The heat transfer characteristics of the R123/R134a/R22 mixture are similar to those of the R123/R134a mixture (mole fraction: 0.502/0.498) observed in the previous flow boiling experiment which indicates that major heat transfer mechanism in the microchannel is dominated by evaporation of thin liquid film around the elongated bubbles. The large reduction of heat transfer coefficients compared with pure refrigerant is observed in micro-channel flow boiling by mass transfer effect of mixed refrigerant.
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Lewis, Ryan, Hayley Schneider, Yunda Wang, Ray Radebaugh, and Y. C. Lee. "Two Phase Flow Patterns and Cooling Power of Mixed Refrigerant in Micro Cryogenic Coolers." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73110.
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Micro cryogenic coolers (MCCs) operating in the Joule-Thomson cycle with mixed refrigerants offer an attractive way to decrease the size, cost, and power draw required for cryogenic cooling. Recent studies of MCCs with mixed refrigerants have, when employing pre-cooling, shown pulsating flow-rates and oscillating temperatures, which have been linked to the refrigerant flow regime in the MCC. In this study we investigate those flow regimes. Using a high-speed camera and optical microscopy, it is found that the pulsations in flow correspond to an abrupt switch from single-phase vapor flow to single-phase liquid flow, followed by 2-phase flow in the form of bubbles, liquid slugs, and liquid slug-annular rings. After this period of 2-phase flow, the refrigerant transitions back to single-phase vapor flow for the cycle to repeat. Under different pre-cooling temperatures, the mole fraction of the vapor-phase refrigerant, as measured by molar flow-rate, agrees reasonably well with the quality of the refrigerant at that temperature as calculated by an equation of state. The frequency of pulsation increases with liquid fraction in the refrigerant, and the volume of liquid in each pulse only weakly increases with increasing liquid fraction. The cooling power of the liquid-flow is up to a factor of 7 greater than that of the 2-phase flows and single-phase vapor flow.
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Nie, Jianhu, Yitung Chen, Bunsen Wong, and Lloyd C. Brown. "Numerical Study of Nozzle Design on Cadmium Quenching Process in Thermochemical Splitting of Water." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12862.
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Three-dimensional liquid-gas flow with condensation during cadmium quenching process for hydrogen production was numerically simulated in order to effectively guide the design of solar decomposer and vapor quencher. The mixture model was selected for modeling the multiphase flow, and the two-equation RNG k-ε model was used to model the turbulent flow and heat transfer. Numerical results including velocity, temperature, pressure, and mole fraction distributions were obtained for different nozzle designs. Numerical results showed that flow is relatively low in the decomposer and close to the bottom and the top inlets. The maximum velocity develops in the region near the entrance of the quenching nozzle as the nozzle angle is small. As the nozzle angle is large, the maximum velocity appears in the exit tube. Temperature, pressure and cadmium vapor distributions are also directly affected by the nozzle angle.
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Wagner, Bernhard, Bruno Frackowiak, Pierre Gajan, and Alain Strzelecki. "Fuel Vapor Concentration Measurements by Laser Induced Fluorescence and Infra-Red Extinction: An Investigation on a Monodisperse Droplet Stream." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59949.
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The vapor mole fraction field around a stream of monodisperse acetone droplets is investigated by Planar Laser Induced Fluorescence (PLIF) and Infra-Red Extinction (IRE). The PLIF works develop an interface positioning method based on the Lorenz-Mie Theory and on geometrical optics, which can be applied to the images despite the blooming effect caused by the liquid phase. Quantitative results obtained at two different injection temperatures concur with the numerical predictions. IRE results — taken at a high repetition rate on the same configuration — are presented. The dynamical behavior, possibilities and constraints of the employed techniques are discussed and an outlook to following investigations is given. This paper presents some PLIF and IRE basics, a description of the test rigs, the post processing of the obtained data and a comparison of the results to a simplified numerical calculation. Finally a discussion of the results and suggestions for improvements are proposed.
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Abou-Ellail, Mohsen M., Ryoichi S. Amano, Samer Elhaw, and Mohamed Saeed. "Numerical Simulation of Hydrogen-Air Reacting Flows in Rectangular Channels With Catalytic Surface Reactions." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38519.
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Catalytic combustion of hydrogen-air boundary layers involves the adsorption of hydrogen and oxygen into a platinum coated surface, chemical reactions of the adsorbed species and the desorption of the resulting products. Re-adsorption of some produced gases is also possible. The catalytic reactions can be beneficial in porous burners and catalytic reactors that use low equivalence ratios. In this case the porous burner flame can be stabilized at low temperatures to prevent any substantial gas emissions, such as nitrogen oxides. The present paper is concerned with the numerical computations of momentum transfer, heat transfer and chemical reactions in rectangular channel flows of hydrogen-air mixtures. Chemical reactions are included in the gas phase as well as on the solid platinum surfaces. In the gas phase, eight species are involved in 26 elementary reactions. On the platinum hot surfaces, additional surface species are included that are involved in 16 additional surface chemical reactions. The platinum surface temperature distribution is pre-specified, while the properties of the reacting flow are computed. The flow configuration investigated in the present paper is that of a rectangular channel burner. Finite-volume equations are obtained by formal integration over control volumes surrounding each grid node. Hybrid differencing is used to ensure that the finite-difference coefficients are always positive or equal to zero to reflect the real effect of neighboring nodes on a typical central node. The finite-volume equations of the reacting gas flow properties are solved by a combined iterative-marching algorithm. On the platinum surfaces, surface species balance equations, under steady-state conditions, are solved numerically. A non-uniform computational grid is used, concentrating most of the nodes in the boundary sub-layer adjoining the catalytic surfaces. The channel flow computational results are compared with recent detailed experimental data for similar geometry. In this case, the catalytic surface temperature profile along the x-axis was measured accurately and is used in the present work as the boundary condition for the gas phase energy equation. The present numerical results for the gas temperature, water vapor mole fraction and hydrogen mole fraction are compared with the corresponding experimental data. In general, the agreement is very good especially in the first 105 millimeters. However, some differences are observed in the vicinity of the exit section of the rectangular channel. The numerical results show that the production of water vapor is very fast near the entrance section followed by a much slower reaction rate. Gas phase ignition is noticed near the catalytic surface at a streamwise distance of about 120 mm. This gas-phase ignition manifests itself as a sudden increase in the mole fractions of OH.
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Amano, Ryoichi S., Mohsen M. Abou-Ellail, and S. Kaseb. "Numerical Predictions of Hydrogen-Air Rectangular Channel Flows Augmented by Catalytic Surface Reactions." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10457.
Full textAbstract:
Catalytic combustion of hydrogen-air boundary layers involves the adsorption of hydrogen and oxygen into a platinum coated surface, chemical reactions of the adsorbed species and the desorption of the resulting products. Readsorption of some produced gases is also possible. The catalytic reactions can be beneficial in porous burners and catalytic reactors that use low equivalence ratios. In this case the porous burner flame can be stabilized at low temperatures to prevent any substantial gas emissions, such as nitrogen oxides. The present paper is concerned with the numerical computations of momentum transfer, heat transfer and chemical reactions in rectangular channel flows of hydrogen-air mixtures. Chemical reactions are included in the gas phase as well as on the solid platinum surfaces. In the gas phase, eight species are involved in 26 elementary reactions. On the platinum hot surfaces, additional surface species are included that are involved in 16 additional surface chemical reactions. The platinum surface temperature distribution is pre-specified, while the properties of the reacting flow are computed. The flow configuration investigated in the present paper is that of a rectangular channel burner. Finite-volume equations are obtained by formal integration over control volumes surrounding each grid node. Hybrid differencing is used to ensure that the finite-difference coefficients are always positive or equal to zero to reflect the real effect of neighboring nodes on a typical central node. The finite-volume equations of the reacting gas flow properties are solved by a combined iterative-marching algorithm. On the platinum surfaces, surface species balance equations, under steady-state conditions, are solved numerically. A non-uniform computational grid is used, concentrating most of the nodes in the boundary sub-layer adjoining the catalytic surfaces. The channel flow computational results are compared with recent detailed experimental data for similar geometry. In this case, the catalytic surface temperature profile along the x-axis was measured accurately and is used in the present work as the boundary condition for the gas phase energy equation. The present numerical results for the gas temperature, water vapor mole fraction and hydrogen mole fraction are compared with the corresponding experimental data. In general, the agreement is very good especially in the first 105 millimeters. However, some differences are observed in the vicinity of the exit section of the rectangular channel. The numerical results show that the production of water vapor is very fast near the entrance section flowed by a much slower reaction rate. Gas phase ignition is noticed near the catalytic surface at a streamwise distance of about 120 mm. This gas-phase ignition manifests itself as a sudden increase in the mole fractions of OH, H and O.
Reports on the topic "Vapor mole fraction"
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2021.2141.
Full textAbstract:
In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2022.2141.
Full textAbstract:
In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
3
Cohen, Shabtai, Melvin Tyree, Amos Naor, Alan N. Lakso, Terence L. Robinson, and Yehezkiel Cohen. Influence of hydraulic properties of rootstocks and the rootstock-scion graft on water use and productivity of apple trees. United States Department of Agriculture, 2001. http://dx.doi.org/10.32747/2001.7587219.bard.
Full textAbstract:
This one year exploratory project investigated hydraulic architecture of apple dwarfing rootstocks. The hypothesis was that hydraulic conductance is correlated with rootstock vigor. A previous study of trees on three rootstocks in Israel showed that dwarfed trees used less water than un-dwarfed trees. Analysis showed that if the tree maintains leaf water potentials above minimum values, then this implies that the dwarfed trees have lower leaf conductance, which may also be the cause of dwarfing. The current project studied small 2-year old unworked rootstock trees, and full sized trees bearing commercial yields. In both cases hydraulic conductance was determined with two methods - the non-destructive evaporative flux (EF)-leaf water potential (L WP) method, and a destructive method in which water was forced through the plant at known pressure using the "high pressure flow meter" (HPFM). Detailed work allowed measurement of conductance of the rootstock-scion union. This was achieved both with the HPFM and with the EF-LWP methods, the former in the US and the latter in Israel. Direct measurements of leaf conductance were made, and carbon isotope ratios ( d ¹³ C) were determined for leaves sampled at the end of the season. The latter can indicate sustained differences in leaf conductance behavior. HPFM and EF-LWP methods did not give the same results. In the small plants results were similar in magnitude, but not significantly correlated. In large trees, EF- L WP measurements were a fraction of those obtained with the HPFM. The latter indicates that some of the xylem is not normally functional but transports water when pressurized. Additional experimental work targeted this result. Xylem was stained before and after perfusion with water at high pressure. This showed that at least for one rootstock a significant amount of xylem was blocked before perfusion. The "air method" for determining xylem vessel properties was improved and employed. Length, radius and density of xylem vessels of different rootstocks were found to be similar, and significant differences found were not clearly related to rootstock vigor. Measurements in the commercial orchard in Israel showed that the graft union in a dwarfing rootstock was a large obstacle for water transport (i.e. had a high resistance). This apparently led to low leaf conductance to water vapor, as indicated by lower d ¹³ C, which implies low internal CO ₂ concentrations. In the US orchard, d ¹³ C in 2001 was correlated with rootstock vigor, and significant differences were found in leaf conductance. However, the d ¹³ C differences were not observed in 2002, were opposite to those found in the Israeli orchard, and measurements of the graft union with the HPFM did not find large resistances. We speculate that the graft union is not necessarily a large impediment to water transport unless the scion starts to separate from the rootstock. It was concluded that significant differences in hydraulic conductance exist between different dwarfing rootstocks. These differences may be caused by differences in xylem properties and in the degree of cavitation, as well as resistance in the graft union. However, no general relationship to rootstock vigor was found. Therefore, hydraulic conductance alone cannot explain dwarfing, but may be one of two or more factors that lead to dwarfing. Future work should integrate more factors with hydraulic relations, e.g. nutrient and solute transport and production of hormones.