Relevant bibliographies by topics / Vapour density

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  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
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Academic literature on the topic 'Vapour density'

Author: Grafiati
Published: 4 June 2021
Last updated: 12 February 2022

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Journal articles on the topic "Vapour density"

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Nagarajan, Veerappan, Arunachalam Thayumanavan, and Ramanathan Chandiramouli. "Magnesium ferrite nanostructures for detection of ethanol vapours - a first-principles study." Processing and Application of Ceramics 11, no. 4 (2017): 296–303. http://dx.doi.org/10.2298/pac1704296n.

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The adsorption behaviour and electronic properties of ethanol vapour on MgFe2O4 ceramic nanostructures are studied using density functional theory technique. The structural stability of MgFe2O4 nanostructure is determined with the help of formation energy. The adsorption behaviour of ethanol molecules on MgFe2O4 base material is analysed in terms of average energy gap variation, Mulliken charge transfer, band gap and adsorption energy. The most prominent adsorption sites of ethanol vapours on MgFe2O4 nanostructure are investigated at atomistic level. The density of states spectrum reveals the clear picture about the electronic properties of MgFe2O4 nanostructure. The density of states and electronic band gap confirmed the adsorption of ethanol vapours on MgFe2O4 nanostructure. The changes in the energy band gap and density of states are observed upon adsorption of ethanol vapour molecules on MgFe2O4 nanostructure. The density of states spectrum also confirms the changes in peak maxima due to the transfer of electrons between MgFe2O4 nanostructure and ethanol vapours. The adsorption of oxygen atom from ethanol vapour on iron in MgFe2O4 is found to be more prominent rather than other adsorption sites. The findings show that MgFe2O4 nanostructure can be utilized to sense the presence of ethanol vapour in the atmosphere.
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Camejo, M. D., and L. L. Bonilla. "Theory of homogeneous vapour condensation and surface deposition from boundary layers." Journal of Fluid Mechanics 706 (July 6, 2012): 534–59. http://dx.doi.org/10.1017/jfm.2012.278.

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AbstractHomogeneous condensation of vapours mixed with a carrier gas in the stagnation point boundary layer flow near a cold wall is considered. There is a condensation region near the wall with supersaturated vapour. Assuming that the surface tension times the molecular area is much larger than the thermal energy far from the wall, droplets are nucleated exclusively in a narrow nucleation layer where the Zeldovich flux of clusters surpassing the critical nucleus size is at a maximum. The vapour condenses in the free molecular regime on the droplets, which are thermophoretically attracted to the wall. Unlike the narrow condensation region for heterogeneous condensation on solid particles, in the case of homogeneous condensation the condensation region is wide even when the rate of vapour scavenging by droplets is large. A singular perturbation theory of homogeneous vapour condensation in boundary layer flow approximates very well the vapour and droplet density profiles, the nucleation layer and the deposition rates at the wall for wide ranges of the wall temperature and the scavenging parameter $B$. A key point in the theory is to select a trial vapour number density profile among a one parameter family of profiles between an upper and a lower bound. The maximum of the Zeldovich flux for supercritical nuclei provides the approximate location of the nucleation layer and an approximate droplet density profile. Then the condensate number of molecules and the vapour density profile are calculated by matched asymptotic expansions that also yield the deposition rates. For sufficiently large wall temperatures, a more precise corrected asymptotic theory is given.
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Castellano, Nesvit E., Eldo E. Ávila, and Clive P. R. Saunders. "Vapour density field of mixed-phase clouds." Atmospheric Research 88, no. 1 (April 2008): 56–65. http://dx.doi.org/10.1016/j.atmosres.2007.10.002.

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Zhao, Qingzhi, Yibin Yao, and Wanqiang Yao. "Troposphere Water Vapour Tomography: A Horizontal Parameterised Approach." Remote Sensing 10, no. 8 (August 7, 2018): 1241. http://dx.doi.org/10.3390/rs10081241.

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Global Navigation Satellite System (GNSS) troposphere tomography has become one of the most cost-effective means to obtain three-dimensional (3-d) image of the tropospheric water vapour field. Traditional methods divide the tomography area into a number of 3-d voxels and assume that the water vapour density at any voxel is a constant during the given period. However, such behaviour breaks the spatial continuity of water vapour density in a horizontal direction and the number of unknown parameters needing to be estimated is very large. This is the focus of the paper, which tries to reconstruct the water vapor field using the tomographic technique without imposing empirical horizontal and vertical constraints. The proposed approach introduces the layered functional model in each layer vertically and only an a priori constraint is imposed for the water vapor information at the location of the radiosonde station. The elevation angle mask of 30° is determined according to the distribution of intersections between the satellite rays and different layers, which avoids the impact of ray bending and the error in slant water vapor (SWV) at low elevation angles on the tomographic result. Additionally, an optimal weighting strategy is applied to the established tomographic model to obtain a reasonable result. The tomographic experiment is performed using Global Positioning System (GPS) data of 12 receivers derived from the Satellite Positioning Reference Station Network (SatRef) in Hong Kong. The quality of the established tomographic model is validated under different weather conditions and compared with the conventional tomography method using 31-day data, respectively. The numerical result shows that the proposed method is applicable and superior to the traditional one. Comparisons of integrated water vapour (IWV) of the proposed method with that derived from radiosonde and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data show that the root mean square (RMS)/Bias of their differences are 3.2/−0.8 mm and 3.3/−1.7 mm, respectively, while the values of traditional method are 5.1/−3.9 mm and 6.3/−5.9 mm, respectively. Furthermore, the water vapour density profiles are also compared with radiosonde and ECMWF data, and the values of RMS/Bias error for the proposed method are 0.88/0.06 g/m3 and 0.92/−0.08 g/m3, respectively, while the values of the traditional method are 1.33/0.38 g/m3 and 1.59/0.40 g/m3, respectively.
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Xia, P., C. Cai, and Z. Liu. "GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles." Annales Geophysicae 31, no. 10 (October 24, 2013): 1805–15. http://dx.doi.org/10.5194/angeo-31-1805-2013.

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Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3.
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Bottomley, G. A., and G. H. P. Seiflow. "Vapour pressure and vapour density of halothane (2-bromo-2-chloro-1,1,1-trifluoroethane)." Journal of Applied Chemistry 13, no. 9 (May 4, 2007): 399–402. http://dx.doi.org/10.1002/jctb.5010130905.

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Barabash, V., A. Osepian, and P. Dalin. "Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere." Annales Geophysicae 32, no. 3 (March 11, 2014): 207–22. http://dx.doi.org/10.5194/angeo-32-207-2014.

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Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)n and O2+(H2O)n hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.
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Jalota, SK. "Evaporation through a soil mulch in relation to mulch characteristics and evaporativity." Soil Research 31, no. 2 (1993): 131. http://dx.doi.org/10.1071/sr9930131.

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A simple equation describing the effects of atmospheric parameters and soil mulch characteristics upon vapour flux density through a dry soil mulch was successfully developed. Determination of vapour flux density was made from columns of diameter 0.1 m and length 0.95 m. These were filled with silt loam and sandy loam soils with surfactant-treated soil mulch on the surface which varied in thickness and porosity. The experiments were conducted under different atmospheric evaporativities (E0), which comprised a number of combinations of wind speed and ambient temperature. The observed vapour flux density and that computed with Hanks' equation matched well. The results indicated that evaporation under a given E0 was affected more by temperature than wind speed. However, vapour flux density showed a strong interaction with wind speed, temperature and the soil mulch characteristics such as porosity and thickness.
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Sokolowski, Stefan, and Johann Fischer. "‘Liquid–vapour’ density profiles for fluids in pores from density functional theory." J. Chem. Soc., Faraday Trans. 89, no. 5 (1993): 789–94. http://dx.doi.org/10.1039/ft9938900789.

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Krebs, P., and B. Lamatsch. "Electron mobility in low-density saturated acetonitrile vapour." Journal of Physics B: Atomic and Molecular Physics 20, no. 18 (September 28, 1987): 4673–78. http://dx.doi.org/10.1088/0022-3700/20/18/008.

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Dissertations / Theses on the topic "Vapour density"

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Marzougui, Jaafar Salsabil. "Transfert d'un composé organo-chloré depuis une zone source localisée en zone non saturée d'un aquifère poreux vers l'interface sol-air : expérimentations et modélisations associées." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAH003/document.

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Deux expériences ont été menées sur la plate-forme expérimentale "SCERES" afin d'évaluer les concentrations et les flux de vapeurs de TCE dans SCERES en présence de deux dalles de béton fissurées installées, l'une après l'autre, à la surface de SCERES. Cet aquifère poreux est un milieu hétérogène de grande échelle (25 x 12 x 3 m3). Les résultats ont montré que le panache de vapeur de TCE couvre la plupart du bassin au bout de 3 semaines depuis la création de la zone source de TCE dans le sous sol. L'hétérogénéité du site SCERES a engendrée une distribution verticale non uniforme de la concentration de vapeurs de TCE. La simulation du panache de vapeur dans SCERES a été effectuée au moyen du code de calcul multiphasique "SIMUSCOPP". La présence sur SCERES de la dalle de béton, un milieu peu perméable et peu diffusif, a constitué une "barrière" en vue du transfert de vapeurs de TCE vers l'interface dalle/atmosphère. Afin de mieux quantifier le flux de vapeurs à travers la dalle de béton, une étude de coefficient de diffusion et de perméabilité des deux dalles a été réalisée. Un mouvement vertical ascendant du toit de la nappe a généré un fort gradient de pression motrice de l'air du sol. Ceci a engendré une forte augmentation des flux de vapeurs à l'interface sol/atmosphère. La quantification de ces flux de vapeurs a été effectuée à l'aide d'une solution semi analytique basée sur la loi de Fick et la loi de Darcy en tenant compte à la fois de l'effet de gradient de pression motrice et l'effet de densité de vapeurs sur le transfert de vapeurs vers la surface du sol. L'intrusion de vapeurs de TCE dans le bâtiment modèle, installé sur la dalle de béton, a été générée par une mise en dépression dans ce dernier. Ce qui a fait augmenter la concentration de vapeurs de TCE sous la dalle ainsi dans le bâtiment. La simulation de l'intrusion de vapeurs dans l'air intérieur de bâtiment a été réalisée par l'intermédiaire du code de calcul multiphysics "COMSOL", avec lequel nous avons démontré l'évolution de la concentration de vapeurs obtenues expérimentalement dans le bâtiment et qui dépend directement de la variation spatio-temporelle du flux massique à travers la dalle
Two experiments were conducted on the experimental platform "SCERES" to assess the TCE vapour concentrations and fluxes in SCERES with two concrete slabs installed, one after the other, on the ground surface. This artificial aquifer is a large scale (25 x 12 x 3 m3) heterogeneous porous medium. The results showed that the TCE vapour plume covers most of the basin 3 weeks after the creation of the TCE source area in unsaturated zone. The heterogeneity of SCERES has generated a non uniform vertical distribution of the TCE vapour concentration. Simulation of vapour plume in SCERES was carried out by the multiphase code "SIMUSCOPP".The presence in SCERES of a low permeability and low diffusive medium compared to the sand in the basin,as a concrete slab, constituted a "barrier" for the transfer of TCE vapour to the interface concrete slab / atmosphere. To better quantify the TOE fluxes through the concrete slab, a study of diffusion coefficient and permeability of both concrete slabs was done. An upward vertical movement of the water table has generated a strong soil air pressure driving gradient, which led to a strong increase in the TCE vapour concentrations near the surface which has increased the vapour fluxes at the interface soil / atmosphere. Quantification of vapour fluxes at the interfaces soil / atmosphere and concrete slab / atmosphere was performed using a semi analytical approach based onFick's and Darcy's laws by taking into account both the effect of the driving pressure gradient and the effect of density vapour on the vapour transfer towards the soil surface.The intrusion of TCE vapours into the model building installed on the concrete slab was generated by creating a vacuum. The results showed that, during the TCE vapour suction from the model building, the concentration of TCE vapours under the concrete slab and in the building increases. Simulation of vapour intrusion into indoor air was done by the computational Multiphysics code "COMSOL", allowing simulation of the evolution of the vapour concentration obtained experimentally in the building. Il was shown that they depend directly on the spatial-temporal variation of the mass flux through the slab
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Van, Regemorter Tanguy. "The Influence of Dopants on the Growth of Diamond by CVD." Doctoral thesis, Uppsala universitet, Institutionen för materialkemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9539.

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Diamond is an important material in many industrial applications (e.g., machining of hard materials, bio-electronics, optics, electronics, etc.) because of its exceptional properties such as hardness, tolerance to aggressive environments, compatibility with human tissues, and high carrier mobility. However, a highly controlled method for growing artificial high-purity diamond on a range of different substrates is needed to exploit these exceptional properties. The Chemical Vapour Deposition (CVD) method is a useful tool for this purpose, but the process still needs to be developed further to achieve better control of growth. In this context, the introduction of dopant species into the gas phase has been shown to strongly influence growth rate and surface morphology. Density Functional Theory (DFT) methods are used to deepen our atomic-level understanding of the effect of dopants on the mechanism for CVD growth on diamond. More specifically, the effect of four dopants (N, P, B and S) has been studied on the important reaction steps in the growth mechanism of diamond. Substitution of N into the diamond lattice has generally been found to disfavour critical reaction steps in the growth of the 100-face in diamond. This negative effect has been related to electron transfer from the N dopant into an empty surface state, e.g., a surface carbon radical. In addition, strong surface stabilization is observed for N substitution in certain sites via a beta-scission reconstruction, with the formation of sp2 carbon. These observations correlate well with observed surface degradation and decrease in growth rate when a high concentration of nitrogen gas is introduced into the CVD growth process. The effect of co-adsorbed P, S and B onto the diamond surface has also been investigated for two reaction steps: CH3 adsorption and H abstraction. While P and B are observed to influence these reaction steps, the effect of S is rather limited.
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Arvidsson, Igor. "Theoretical Investigations of Boron Related Materials Using DFT." Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7889.

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In the history of Chemistry, materials chemists have developed their ideas mainly by doing experiments in laboratories. The underlying motivation for this laboratory work has generally been pure curiosity or the ambition to find a solution to a specific problem. Minor changes in the composition or structure of a material can cause major changes in its properties. The development of powerful computers has now opened up the possibility to calculate properties of new materials using quantum mechanical methods.

The Chemistry of different boron-related materials has been evaluated in this thesis by Density Functional Theory (DFT). Cubic boron nitride (c-BN) is a most interesting material for the microelectronics and tool industry. During thin film deposition of c-BN, several problems arise which most often result in unwanted BN isomorphs. Chemical processes at the (110) and (111) surface of c-BN have been investigated in order to shed light upon some of these complex processes. Typically adsorption energies and surface reconstruction were found to differ significantly between the two surfaces.

Other materials investigated are layered transition-metal diborides (MeB2). Incorporation of transition-metal atoms into elemental boron in its most fundamental structure, ά-boron, has also been investigated. The calculations on MeB2 focused on the stability of the planar compared to the puckered structure of MeB2. Stability was investigated by calculating Density of States (DOS) and bond populations. Deviations in the cell parameters from their ideal values were also considered.

A separate project concerned reactivity of the TiB2(001) surface. Molecular and dissociated adsorption energies and adsorption geometries were calculated for H2, H2O and O2. It was concluded that the titanium surface was more reactive than the boron surface and that the adsorption energies were comparable to or stronger than other well known surface-active compounds like TiO2.

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Li, Hailong. "Thermodynamic Properties of CO2 Mixtures and Their Applications in Advanced Power Cycles with CO2 Capture Processes." Doctoral thesis, KTH, Energiprocesser, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9109.

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The thermodynamic properties of CO2-mixtures are essential for the design and operation of CO2 Capture and Storage (CCS) systems. A better understanding of the thermodynamic properties of CO2 mixtures could provide a scientific basis to define a proper guideline of CO2 purity and impure components for the CCS processes according to technical, safety and environmental requirements. However the available accurate experimental data cannot cover the whole operation conditions of CCS processes. In order to overcome the shortage of experimental data, theoretical estimation and modelling are used as a supplemental approach.   In this thesis, the available experimental data on the thermodynamic properties of CO2 mixtures were first collected, and their applicability and gaps for theoretical model verification and calibration were also determined according to the required thermodynamic properties and operation conditions of CCS. Then in order to provide recommendations concerning calculation methods for engineering design of CCS, totally eight equations of state (EOS) were evaluated for the calculations about vapour liquid equilibrium (VLE) and density of CO2-mixtures, including N2, O2, SO2, Ar, H2S and CH4.   With the identified equations of state, the preliminary assessment of impurity impacts was further conducted regarding the thermodynamic properties of CO2-mixtures and different processes involved in CCS system. Results show that the increment of the mole fraction of non-condensable gases would make purification, compression and condensation more difficult. Comparatively N2 can be separated more easily from the CO2-mixtures than O2 and Ar. And a lower CO2 recovery rate is expected for the physical separation of CO2/N2 under the same separation conditions. In addition, the evaluations about the acceptable concentration of non-condensable impurities show that the transport conditions in vessels are more sensitive to the non-condensable impurities and it requires very low concentration of non-condensable impurities in order to avoid two-phase problems.   Meanwhile, the performances of evaporative gas turbine integrated with different CO2 capture technologies were investigated from both technical and economical aspects. It is concluded that the evaporative gas turbine (EvGT) cycle with chemical absorption capture has a smaller penalty on electrical efficiency, while a lower CO2 capture ratio than the EvGT cycle with O2/CO2 recycle combustion capture. Therefore, although EvGT + chemical absorption has a higher annual cost, it has a lower cost of electricity because of its higher efficiency. However considering its lower CO2 capture ratio, EvGT + chemical absorption has a higher cost to avoid 1 ton CO2. In addition the efficiency of EvGT + chemical absorption can be increased by optimizing Water/Air ratio, increasing the operating pressure of stripper and adding a flue gas condenser condensing out the excessive water.
QC 20100819
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Gill, Yasir Q. "Preparation and characterization of polyethylene based nanocomposites for potential applications in packaging." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18052.

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The objective of my work was to develop HDPE clay nanocomposites for packaging with superior barrier (gas and water) properties by economical processing technique. This work also represents a comparative study of thermoplastic nanocomposites for packaging based on linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon12. In this study properties and processing of a series of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon 12 nanocomposites based on Na-MMT clay and two different aspect ratio grades of kaolinite clay are discussed.
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Atwa, Mohamed. "Chemical Vapor Deposition Growth and Density Functional Theory Calculations of Trilayer Graphene." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206117.

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Density functional theory was employed to investigate the energetics of ABA, ABC, and intermediary stacked phases for both pristine and s-triazine functionalized graphene trilayers. The energy of the ABC-stacked phase relative to the pristine ABA-stacked ground state showed a 94% increase when s-triazine was adsorbed to the graphene surface, confirming previous studies of the ability of s-triazine to facilitate the ABC to ABA phase-transition. This work is outlined in an enclosed publication titled “Trilayer Graphene as a Candidate Material for Phase Change Memory Applications.” Subsequently, low-pressure CVD was used to synthesize single-crystal graphene trilayers of up to 200 µm, the largest reported thus far. The defect density, stacking density, and morphology of the CVD-grown graphene trilayers are evaluated using Raman spectroscopy. The layers are also shown to be directly discernable as-grown on copper substrates using dark-field optical microscopy even without contrast oxidation of the copper film, representing a quick and reliable method for their identification. Slow-etching of the graphene yielded well-aligned, hexagonal domains further indicating the high-quality, single-crystalline of the graphene.
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Mairhofer, Jonas [Verfasser], and Joachim [Akademischer Betreuer] Groß. "Modeling properties of the vapor-liquid interface using classical density functional theory and density gradient theory / Jonas Mairhofer ; Betreuer: Joachim Groß." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1179185234/34.

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Lucivero, Vito Giovanni. "Quantum metrology with high-density atomic vapors and squeezed states of light." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/403962.

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Nowadays there is a considerable progress in optical magnetometry and spin noise spectroscopy, which use magnetically-sensitive atomic ensembles and optical read-out, approaching the limits set by quantum mechanics. In recent years optical magnetometers have become the most sensitive instruments for measuring low-frequency magnetic fields, achieving sub-femtotesla sensitivity and surpassing the competitive superconducting quantum interference devices (SQUIDs), and have found applications in biomedicine, geophysics, space science as well as in tests of fundamental physics. Another emerging technique is spin noise spectroscopy (SNS), which allows one to determine physical properties of an unperturbed spin system from its power noise spectrum. In the last decade technological advances like real-time spectrum analyzers and shot-noise-limited detectors have allowed improvements in the sensitivity of spin noise detection leading to a broad range of applications in both atomic and solid state physics. The main goal of this thesis is to address a major outstanding question: whether squeezed light can improve the sensitivity of atomic sensors under optimal sensitivity conditions, typically in a high-density regime due to the statistical advantage of using more atoms. Firstly, we describe the design, construction and characterization of a new versatile experimental apparatus for the study of squeezed-light atomic spectroscopy within a high-density regime (n=¿10¿^12 ¿cm¿^(-3)) and low-noise (¿pT/vHz) magnetic environment. The new experimental system is combined with an existing source of polarization squeezed light based on spontaneous parametric down conversion (SPDC) in a nonlinear crystal, which is the active medium of an optical parametric oscillator. Secondly, we report the first experimental demonstration of quantum-enhanced spin noise spectroscopy of natural abundance Rb via polarization squeezing of the probe beam. We found that input squeezing of 3.0 dB improves the signal-to-noise ratio by 1.5 dB to 2.6 dB over the combined (power¿number density) ranges (0.5 mW to 4.0 mW) ¿ (1.5 ׿10¿^12 ¿cm¿^(-3) to 1.3 ׿10¿^13 ¿cm¿^(-3)), covering the ranges used in optimized spin noise spectroscopy experiments. We also show that squeezing improves the trade-off between statistical sensitivity and broadening effects. Next, we introduce a novel theoretical model by defining a standard quantum limit (SQL) for optically-detected noise spectroscopy, identified as a bound to the covariance of the parameters estimated by fitting power noise spectra. We test the model for spin noise spectroscopy of natural abundance Rb and we demonstrate experimental performance of SNS at the SQL for a coherent probe and below the SQL for a polarization squeezed probe. Finally, we report an optical magnetometer based on amplitude modulated optical rotation (AMOR), using a 85Rb vapor cell, that achieves room temperature sensitivity of 70 fT/vHz at 7.6 µT and we demonstrate its photon shot-noise-limited (SNL) behaviour from 5 µT to 75 µT. While no quantum resources of light were used in this second experiment, the combination of best sensitivity, in the class of room-temperature scalar
Hoy en día existe un considerable progreso en la magnetometría óptica y espectroscopía de ruido de espin, que utilizan conjuntos atómicos magnéticamente sensibles y lectura óptica, acercándose a los límites establecidos por la mecánica cuántica. En los últimos años los magnetómetros ópticos se han convertido en los instrumentos más sensibles para medir los campos magnéticos de baja frecuencia, logrando sensibilidad de sub-femtotesla y superando dispositivos como los superconductores de interferencia cuántica (SQUID), y han encontrado aplicaciones en biomedicina, geofísica, ciencia espacial, así como en varias pruebas de física fundamental. Otra técnica emergente es la espectroscopía de ruido de espin (SNS), que permite determinar las propiedades físicas de un sistema de espin sin perturbarlo por medio de su espectro de potencia de ruido. En la última década, los avances tecnológicos como analizadores de espectro en tiempo real y detectores limitados por el ruido de disparo de fotón han permitido mejoras en la sensibilidad de detección de ruido de spin que conduce a una amplia gama de aplicaciones tanto en la física del estado sólido como en la física atómica. El objetivo principal de esta tesis es responder a una cuestión pendiente e importante: si la "luz comprimida" puede mejorar la sensibilidad de los sensores atómicos en condiciones óptimas para la sensibilidad, típicamente en un régimen de alta densidad debido a la ventaja estadística de utilizar más átomos. En primer lugar, se describe el diseño, construcción y caracterización de un nuevo aparato experimental versátil para el estudio de la espectroscopia atómica con luz comprimida dentro de un régimen de alta densidad (n=¿10¿^12 ¿cm¿^(-3)) y bajo nivel de ruido magnético (¿pT/vHz). El nuevo sistema experimental se combina con una fuente existente de luz comprimida en polarización, basado en el proceso de conversión paramétrica espontánea descendente (SPDC) en un cristal no lineal, que es el medio activo de un oscilador paramétrico óptico. En segundo lugar, se presenta la primera demostración experimental de espectroscopía de espin de Rubidio, en abundancia natural, mejorada a través de la compresión en polarización de la luz de prueba. Se encontró que la entrada de 3.0 dB de luz comprimida mejora la relación señal-ruido de 1.5 dB a 2.6 dB en el intervalo combinado (potencia óptica)¿(densidad atómica) de (0.5 mW to 4.0 mW) ¿ (1.5׿10¿^12 ¿cm¿^(-3) to 1.3׿10¿^13 ¿cm¿^(-3)), que cubre rangos utilizados en los experimentos optimizados de espectroscopía de ruido de espin. También mostramos que la luz comprimida mejora el equilibrio entre la sensibilidad estadística y efectos de ampliación de la resonancia. A continuación, se introduce un nuevo modelo teórico con la definición de un límite cuántico estándar (SQL) para la espectroscopía de ruido detectado ópticamente, identificado como un límite a la covarianza de los parámetros estimados mediante el ajuste de los espectros de potencia de ruido. Probamos el modelo para la espectroscopia de ruido de espin en abundancia natural de rubidio y demostramos el rendimiento experimental de la espectroscopia de ruido al límite cuántico estándar para una haz coherente y por debajo del SQL para una haz de luz comprimida en polarización. Por último, se presenta un magnetómetro óptico basado en rotación óptica modulada en amplitud (AMOR), utilizando una celda de vapor de 85Rb, que logra sensibilidad a la temperatura ambiente de 70 fT/vHz a 7.6 µT y demostramos su limite de ruido de disparo de fotón (SNL) en el intervalo de 5 µT a 75 µT. Si bien no se utilizaron recursos cuánticos de la luz en este segundo experimento, la combinación de la mejor sensibilidad, en la clase de los magnetómetros escalares de temperatura ambiente, y con operación al limite de ruido de disparo hace que el sistema sea un candidato prometedor para la aplicación de luz comprimida a un magnetómetro óptico optimizado con mejor sensibilidad en la clase
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Karlsson, Johan. "Theoretical Routes for c-BN Thin Film Growth." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-191181.

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c-BN has been in focus for several years due to its interesting properties. The possibility for large area CVD is a requirement for the realization of these different properties in various applications. Unfortunately, there are at present severe problems in the CVD growth of c-BN. The purpose with this research project has been to theoretically investigate, using DFT calculations, the possibility for a layer-by-layer CVD growth of c-BN. It could be established that, PEALD, using a BF3-H2-NH3-F2 pulse cycle and a diamond substrate, is a promising method for deposition of c-BN films. The gaseous species will decompose in the plasma and form BFx, H, NHx, and F species (x = 0, 1, 2, 3). The H and F radicals will uphold the cubic structure by completely hydrogenate, or fluorinate, the growing surface. However, surface radical sites will appear during the growth process as a result of atomic H, or F, abstraction reactions. The addition of NHx growth species (x = 0, 1, 2) to B radical sites, and BFx growth species (x = 0, 1, 2) to N radical sites, will then result in a continuous growth of c-BN.
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Stephan, Simon [Verfasser], and Hans [Akademischer Betreuer] Hasse. "Vapor-Liquid Interfaces: Molecular Simulation, Density Gradient Theory, and Experiments / Simon Stephan ; Betreuer: Hans Hasse." Kaiserslautern : Technische Universität Kaiserslautern, 2020. http://d-nb.info/1218530391/34.

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Books on the topic "Vapour density"

1

Domanski, Piotr. Impact of refrigerant property uncertainties on prediction of vapor compression cycle performance. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.

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Cannizzaro, Stanislao. Sunto di un corso di filosofia chimica. Palermo: Sellerio, 1991.

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Escudier, Marcel. Fluids and fluid properties. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198719878.003.0002.

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In this chapter it is shown that the differences between solids, liquids, and gases have to be explained at the level of the molecular structure. The continuum hypothesis makes it possible to characterise any fluid and ultimately analyse its response to pressure difference Δ‎p and shear stress τ‎ through macroscopic physical properties, dependent only upon absolute temperature T and pressure p, which can be defined at any point in a fluid. The most important of these physical properties are density ρ‎ and viscosity μ‎, while some problems are also influenced by compressibility, vapour pressure pV, and surface tension σ‎. It is also shown that the bulk modulus of elasticity Ks is a measure of fluid compressibility which determines the speed at which sound propagates through a fluid. The perfect-gas law is introduced and an equation derived for the soundspeed c.
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Magee, Patrick, and Mark Tooley. Physics in anaesthesia. Edited by Antony R. Wilkes and Jonathan G. Hardman. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199642045.003.0023.

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This chapter covers the basic science of physics relevant to anaesthetic practice. Equipment and measurement devices are covered elsewhere. Starting with fundamentals, atomic structure is introduced, followed by dimensions and units as used in science. Basic mechanics are then discussed, focusing on mass and density, force, pressure, energy, and power. The concept of linearity, hysteresis, and frequency response in physical systems is then introduced, using relevant examples, which are easy to understand. Laminar and turbulent fluid flow is then described, using flow measurement devices as applications of this theory. The concept of pressure and its measurement is then discussed in some detail, including partial pressure. Starting with the kinetic theory of gases, heat and temperature are described, along with the gas laws, critical temperature, sublimation, latent heat, vapour pressure and vaporization illustrated by the function of anaesthetic vaporizers, humidity, solubility, diffusion, osmosis, and osmotic pressure. Ultrasound and its medical applications are discussed in some detail, including Doppler and its use to measure flow. This is followed by an introduction to lasers and their medical uses. The final subject covered is electricity, starting with concepts of charge and current, voltage, energy, and power, and the role of magnetism. This is followed by a discussion of electrical circuits and the rules governing them, and bridge circuits used in measurement. The function of capacitors and inductors is then introduced, and alternating current and transformers are described.
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Buerke, Brian J. A determination of the temperature dependence of the density of Nab2 sinside an alkali metal vapor oven. 1989.

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Center, Lewis Research, ed. A comparison of the Bromination dynamics of pitch-based and vapor-grown graphite fibers. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1986.

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EUPDF, an Eulerian-based Monte Carlo probability density function (PDF) solver: User's manual. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1998.

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Center, Lewis Research, ed. EUPDF, an Eulerian-based Monte Carlo probability density function (PDF) solver: User's manual. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1998.

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EUPDF, an Eulerian-based Monte Carlo probability density function (PDF) solver: User's manual. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1998.

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Center, Lewis Research, ed. EUPDF, an Eulerian-based Monte Carlo probability density function (PDF) solver: User's manual. [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, 1998.

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Book chapters on the topic "Vapour density"

1

Bier, K., F. Ehrler, and G. Theis. "Spontaneous Condensation in Stationary Nozzle Flow of Carbon Dioxide in a Wide Range of Density." In Adiabatic Waves in Liquid-Vapor Systems, 129–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-83587-2_12.

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Lee, J., and F. Ren. "Device Damage During Low Temperature High-Density Plasma Chemical Vapor Deposition." In Handbook of Advanced Plasma Processing Techniques, 575–605. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-56989-0_14.

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Peng, Yuxiang, and Ramana G. Reddy. "Density, Viscosity, Vapor Pressure and Thermal Conductivity of MgCl2+ Mg Salts." In Advances in Molten Slags, Fluxes, and Salts, 1169–75. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119333197.ch125.

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Peng, Yuxiang, and Ramana G. Reddy. "Density, Viscosity, Vapor Pressure and Thermal Conductivity of MgCl2 + Mg Salts." In Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts 2016, 1169–75. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48769-4_125.

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Barocchi, F., M. Sampoli, F. Hensel, J. Rathenow, and R. Winter. "The Depolarized Interaction Induced Light Scattering Spectrum of Mercury Vapor at Low Density." In Collision- and Interaction-Induced Spectroscopy, 357–67. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0183-7_26.

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Rice, S. A. "The Atomic Structure of the Liquid-Vapor Interface of a Metal: An Example of the Influence of Strong Density Dependence of the Interatomic Potential." In Solvay Conference on Surface Science, 129–37. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-74218-7_11.

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Magee, Patrick, and Mark Tooley. "Solubility, Vaporisation and Vaporisers." In The Physics, Clinical Measurement and Equipment of Anaesthetic Practice for the FRCA. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199595150.003.0013.

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In discussing humidity in the preceding chapter, the concept of equilibrium between water and its vapour has been introduced as a thermodynamic concept. The concept of vaporisation of other liquids such as volatile anaesthetic agents follows on naturally from that, but first of all it will be worth taking a detour through a discussion on solubility of gases and vapours in their own and other liquids [Davis 2003]. To maintain simplicity in the discussion on humidity, no mention was made of the presence of air or other gas above the surface of the water, only the water vapour. Depending on the solubility of the gas in the liquid, a variable amount of the gas dissolves in the liquid, whether that be air in water or carbon dioxide in blood. As will be discussed in the section on vaporisation, some molecules of gas enter the liquid and some leave it, depending on their individual kinetic energies, until equilibrium is reached. If the pressure inside the container with the gas or vapour and liquid is increased, then the partial pressure of the gas above the liquid surface increases; this increases the population density of gas molecules, resulting in more of the gas molecules dissolving in the liquid. Henry’s Law states that for a fixed temperature the solubility of a gas in a liquid is proportional to its partial pressure in equilibrium with the liquid. Note the condition of constant temperature because, in addition, solubility decreases with increased temperature. This occurs because an increase in the thermal energy of the dissolved gas molecules increases the partial pressure of the gas and encourages it to come out of solution (see below on vaporisation). Thus gas bubbles are more apparent in liquids that are heated. A historical clinical example of the relevance of ambient pressure and nitrogen solubility in body tissues is in decompression sickness associated with tunnel workers. Modern examples include underwater diving and, to a lesser extent, aviators and space walking astronauts. Nitrogen is a compressible gas and goes into solution in body tissue spaces under compression if the miner, tunnel worker, or diver is breathing ambient air.
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Evans, John. "Water." In Elements of a Sustainable World, 235–72. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198827832.003.0006.

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The physical properties of water provide a framework for many day-to-day experiences: including the energy intrinsic to the melting and boiling of water, and in the increase in vapour density with temperature. The availability of freshwater is sequestered mainly in ice caps and groundwater and most readily acquired water emanates from the rainwater that falls on land. The demands of water for processing (Virtual water) are substantial. Extension fo water supply by desalination of seawater by reverse osmosis is explained. Options for extraction of minerals from seawater are also developed. The challenges posed by heavy elements, pharmaceuticals and plastics on wastewater treatment and drinking water supplies are elaborated
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Weiser, P. S., S. Prawer, K. W. Nugent, A. A. Bettiol, L. I. Kostidis, S. P. Dooley, and D. N. Jamieson. "THE EFFECT OF ION-BEAM INDUCED STRAIN ON THE NUCLEATION DENSITY OF CHEMICAL VAPOUR DEPOSITED DIAMOND." In Ion Beam Modification of Materials, 752–56. Elsevier, 1996. http://dx.doi.org/10.1016/b978-0-444-82334-2.50143-x.

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"Vapor Density." In Rules of Thumb for Petroleum Engineers, 705. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2017. http://dx.doi.org/10.1002/9781119403647.ch322.

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Conference papers on the topic "Vapour density"

1

Brown, Daniel J., R. Kunnemeyer, and A. I. McIntosh. "Radial Excited-State Density Effects In A Small-Bore Copper Vapour Laser." In OE/LASE '89, edited by Jin J. Kim, Randy Kimball, and P. J. Wisoff. SPIE, 1989. http://dx.doi.org/10.1117/12.951224.

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Inada, Y., T. Kamiya, S. Matsuoka, A. Kumada, H. Ikeda, and K. Hidaka. "Simultaneous measurement of two-dimensional electron and vapour density distribution over vacuum arc." In 2014 International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV). IEEE, 2014. http://dx.doi.org/10.1109/deiv.2014.6961662.

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Akinwumi, S. A., T. V. Omotosho, A. A. Willoughby, J. S. Mandeep, and M. Abdullah. "Seasonal variation of surface radio refractivity and water vapour density for 48 stations in Nigeria." In 2015 International Conference on Space Science and Communication (IconSpace). IEEE, 2015. http://dx.doi.org/10.1109/iconspace.2015.7283753.

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4

SAZHIN, SERGEI, and IRINA SHISHKOVA. "Kinetic and MD modelling of automotive fuel droplets heating and evaporation: recent results." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4593.

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Recent results of the investigation of kinetic and molecular dynamics (MD) models for automotive fuel droplet heating and evaporation are summarised. The kinetic model is based on the consideration of the kinetic region in the close vicinity of the surface of the heated and evaporating droplets, where the motion of molecules is described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region away from this surface. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. A new self-consistent kinetic model for heating and evaporation of Diesel fuel droplets is briefly described. The values of temperature and vapour densities at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour components in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions are equal. At first, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following this procedure, are used to calculate the corrected values of hydrodynamic heat and species mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region. It is shown that this process quickly converges and leads to self-consistent values for both heat and mass fluxes. Boundary conditions at the surface of the droplet for kinetic calculations are inferred from the MD calculations. These calculations are based on the observation that methyl (CH3 ) or methylene (CH2 ) groups in n-dodecane (approximation of Diesel fuel) molecules can be regarded as separate atom-like structures in a relatively simple United Atom Model. Some results of the application of quantum chemical methods to the estimation of the evaporation/condensation coefficient are discussed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4593
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Wilhelmsson, Charlotte, Jinliang Yuan, and Bengt Sunden. "Water Condensation and Two-Phase Flow Modeling for a Plate Heat Exchanger Channel." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41635.

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There are water vapour condensation and two-phase flow in plate heat exchangers when they are used as condensers. Water phase change and flow dynamics modelling is an important but complicated task due to large change in water physical/transport properties across the water liquid-vapour interface boundary. In particular, singular-link behaviour in governing equations is present due to the large step change in the density when computational fluid dynamics (CFD) is employed. Conventional methods using ensemble averaged parameters such as void fraction are impossible to be applied to cases where high-resolution calculations and detailed analysis are required. In this study, a CFD approach is employed to model water vapour condensation and two-phase flow in a channel relevant for plate heat exchanger parallel plates. The developed model is based on the governing equations which are directly solved for the entire single- and two-phase fields. The water phase change and two-phase flow are treated by employing a water liquid-phase fraction factor based on the total enthalpy in each computational cell. The factor is defined as the ratio of the total enthalpy differential to the latent heat of condensation. The thermal-physical properties, such as density, viscosity and conductivity of the two-phase region, are calculated and updated based on the calculated value of the liquid-phase fraction factor until a converged result is reached. It is concluded that, among others, the inlet vapour velocity has significant effects on the water phase change and two-phase flow in the channel, in terms of liquid-water fraction factor distribution.
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Stosic, Zoran V., and Vladimir D. Stevanovic. "Multi-Dimensional Numerical Simulation of Burnout on Horizontal Surface in Pool Boiling." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31367.

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Multidimensional numerical simulation of the atmospheric saturated pool boiling is performed under high heat fluxes, near to and at the occurrence of burnout conditions. Heat flux through the vessel bottom wall is varied and its influence on the pool boiling dynamics is analysed. Dynamics of vapour generation on the heating wall is modelled through the density of nucleation sites and the bubble residence time on the wall. The nucleation sites are determined by a random function. The applied numerical grid is able to represent the nucleation sites on the heating wall for both fresh (polished) and aged (rough) heaters at the atmospheric pool boiling conditions. Results are presented for short time period after the initiation of heat supply and vapour generation on the heating surface, as well as for quasi steady-state conditions after two seconds from pool boiling initiation. The results show a replenishment of the heating surface with water and partial surface wetting for lower heat fluxes, while heating surface dry-out is predicted for high heat fluxes. The influence of the density of nucleation sites and the bubble residence time on the wall on the pool boiling dynamics is investigated. Numerical simulations show that decrease of the density of nucleation sites and increase of bubble residence time on the heating surface (characteristics pertinent to fresh-polished heaters) lead to the reduction of critical heat flux values. Obtained results are in excellent agreement with the recent experimental investigations of the upward facing burnout conditions on the horizontal heated plate. Details of the developed numerical procedure are presented. The introduced method of random spatial and temporal generation of the vapour at the heated wall is a new approach. It enables the macroscopic representation of the population of microscopic vapour bubbles, which are generated at nucleation sites on the heater wall, and which burst through liquid micro-layer in thermal-hydraulic conditions close to the burnout. The applied numerical and modelling method has shown robustness by allowing stable calculations for wide ranges of applied modelling boiling parameters (density of nucleation sites and bubble residence time).
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Gu, Junjie, Masahiro Kawaji, Tracey Smith-Pollard, and James Cotton. "Multi-Channel R134a Two-Phase Flow Measurement Technique for Automobile Air-Conditioning System." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45379.

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This paper presents an improved on-line measurement technique developed to study two-phase flow rate distributions of refrigerants in parallel flow channels of compact heat exchangers and evaporators used in automotive air-conditioning systems. A prototype test station containing a refrigerant flow loop and a multi-channel two-phase flow measuring system, was designed and constructed based on the stratification of two-phase flow in horizontal tubes with relatively large diameters. In this work, glass tubes of 1”, 1.5” and 2” diameter were tested. Upon entering the glass tube, a vapour-liquid refrigerant mixture would readily stratify and the mean velocities of vapour and liquid phases could be measured separately using a hot film anemometer and an ultrasonic flow meter, respectively. Scales taped onto the glass tubes were also used to determine the mean liquid levels, from which the flow area of each phase could be calculated. The product of the flow area, phase density and mean phase velocity would then yield the mass flow rate of each phase. Validation experiments have been performed with R-134a as the working fluid and a 3-channel evaporator test section, designed with three separate outlets and kept under an adiabatic condition. The sum of the flow rates in the glass tubes for each phase was compared with the vapour or liquid flow rate determined from the total mass flow rate measured at the evaporator inlet and a heat balance in the pre-heater section of the pump-driven refrigerant flow loop. Validation tests yielded satisfactory results for both vapor and liquid phases, indicating the soundness of the measurement system based on the stratification tubes as well as the use of an ultrasonic flow meter and hot-film anemometer probes for phase average velocity measurements. The present measurement system has been equipped with seven glass tubes and thus can be used to study liquid and vapor flow rate distributions in commercial compact heat exchangers and improve their performance in automobile air conditioning systems.
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Cannon, James, Natalie Moore, and Ortwin Hess. "The Effect of Molecular Orientation and Temperature on the Flow Dynamics of Water Molecules Through a Carbon Nanotube." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32642.

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Temperature plays a significant role in determining the dynamics of flow on the nanoscale. This is particularly important with carbon nanotubes, which are likely to form an integral part of future nanofluidic and biological devices. We demonstrate through first-principles density-functional theory (DFT) that the energies and temperatures at which individual water molecules are able to enter the nanotube depends very strongly on their orientation. This has a number of implications for the flow of water through the nanotube at different temperatures and densities, particularly when considering low-density water vapour.
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Cannon, James, Natalie Moore, and Ortwin Hess. "The Influence of Molecular Orientation on the Ability of Water to Enter a Carbon Nanotube at Different Temperatures." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52378.

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Temperature plays a significant role in determining the dynamics of flow on the nanoscale. This is particularly important with carbon nanotubes, which are likely to form an integral part of future nanofluidic and biological devices. We demonstrate through first-principles density-functional theory (DFT) that the orientation of the individual water molecules plays a significant role in determining the temperatures and energies at which water is able to enter the nanotube. This has a number of implications for the flow of water through the nanotube at different temperatures and densities, particularly when considering low-density water vapour.
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Stosic, Zoran V., and Vladimir D. Stevanovic. "Three-Dimensional Numerical Simulation of Burnout on Horizontal Surface in Pool Boiling." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45521.

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Abstract:
Prediction of nucleate boiling mechanisms and burnout conditions, when heat transfer coefficient sharply drops and the heating surface destruction could occur are one of the crucial topics in thermal design and safety analyses of various thermal equipment. Although these phenomena have been intensively investigated for decades, various influencing factors and complexity of coupled thermal and fluid dynamic processes have not yet been fully understood. The integral approach towards prediction of nucleate boiling and burnout conditions requires modelling and numerical simulation of micro level phenomena of bubble rise and departure at a numbers of nucleation sites, as well as macroscopic two-phase mixture behaviour on the heating surface. In this paper multidimensional numerical simulation of the atmospheric saturated pool boiling is performed under high heat fluxes, near to and at the occurrence of burnout conditions. Micro level phenomena on the heating surface are modelled with the key parameters of vapour generation on the heating wall, such as bubble nucleation site density, bubble residence time on the heating wall and certain level of randomness in the location of bubble nucleation. Heat flux is non-uniformly distributed on the heating surface with peaks at the nucleation sites. The nucleation sites are determined by a random function, while the mean number of nucleation sites is prescribed according to the material characteristics and roughness of the heating surface. The applied numerical grids are able to represent the nucleation sites on the heating wall for both fresh (polished) and aged (rough) heaters at the atmospheric pool boiling conditions. The macro level phenomena are modelled with two-fluid model of liquid-vapour flow. The interfacial drag is modelled with appropriate closure laws. The applied modelling and numerical methods enable full representation of the two-phase mixture behaviour on the heating surface with inclusion of the swell level prediction. In this way the integral conditions of nucleate pool boiling with the possibility of burnout are simulated and the critical heat flux conditions are predicted. The result of the three-dimensional numerical simulations and analyses are presented as the extension of the previously published two-dimensional numerical results. Here presented three-dimensional investigation is performed in order to take into account more realistically spatial effects of vapour generation and two-phase flow, such as phase dispersion within the two-phase mixture, than it was able with previously performed two-dimensional investigation. Results are presented for short time period after the initiation of heat supply and vapour generation on the heating surface, as well as for quasi steady-state conditions after several seconds from pool boiling initiation. A replenishment of the heating surface with water and partial surface wetting for lower heat fluxes is shown, while heating surface dry-out is observed for high heat fluxes. The influence of the density of nucleation sites and the bubble residence time on the wall on the pool boiling dynamics is investigated. Also, the influence of the heat flux intensity on the pool boiling dynamics is analysed. Numerical simulations show that decrease of the density of nucleation sites and increase of bubble residence time on the heating surface (characteristics pertinent to fresh-polished heaters) lead to the reduction of critical heat flux values. Obtained results are in excellent agreement with the recent experimental investigations of the upward facing burnout conditions on the horizontal heated plate. Details of the developed numerical procedure are presented. The introduced method of random spatial and temporal generation of the vapour at the heated wall is a new approach. It enables the macroscopic representation of the population of microscopic vapour bubbles, which are generated at nucleation sites on the heater wall, and which burst through liquid micro-layer in thermal-hydraulic conditions close to the burnout. The applied numerical and modelling method has shown robustness by allowing stable calculations for wide ranges of applied modelling boiling parameters (density of nucleation sites and bubble residence time).
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Reports on the topic "Vapour density"

1

Chen, Xing. High-Density Plasma Source for Large-Area Chemical Vapor Deposition of Diamond Films. Fort Belvoir, VA: Defense Technical Information Center, December 1994. http://dx.doi.org/10.21236/ada289053.

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