Physical Properties Of Gas Research Articles

The nitrogen-doped porous carbons/PIM mixed-matrix membranes for CO2 separation

Nitrogen-doped porous carbons (NDPC)/polymer of intrinsic microporosity (PIM) mixed-matrix membranes (MMMs) were fabricated via a thermal treatment of the ionic liquids (ILs)/PIM blending membranes, in which the nitrile-containing ILs reacted and formed the NDPC with three-dimensional-connected frame-works after the thermal post-treatment. The chemical characterization was performed by Fourier transform infrared spectroscopy. The thermal property was investigated by thermo-gravimetric analysis. The average inter-chain distance of the MMMs was evaluated by wide-angle X-ray diffraction. The porous structure was evaluated by low-temperature N2 adsorption-desorption analysis. The membrane morphology was investigated by field-emission scanning electron microscopy. The gas transport property of the NDPC/PIM MMMs was reported. The relationship between gas transport property and physical properties was also discussed. Compared with the original PIM-1 membrane, the NDPC/PIM MMMs displayed much higher CO2 permeability at the cost of an acceptable, slight reduction in CO2/N2 selectivity. The outstanding permeation-separation performance for CO2/N2 exceeds the Robeson upper bound line.

Development of a transient non-isothermal two-phase flow model for gas kick simulation in HTHP deep well drilling

The simulation of gas/liquid two-phase flow, considering the heat transfer between the annulus fluid and the surrounding environment, is of significance in predicting temperature and pressure distributions after a gas kick in HTHP deep well drilling. This paper presents the development of a transient non-isothermal two-phase flow model for the dynamic simulation of multiphase flow in the wellbore after a gas kick. The drift-flux model is used to describe gas/liquid two-phase flow, and multiple transient energy conservation equations are used for predicting temperature profiles of fluids in the drillpipe, drillpipe, the fluid in the annulus, casing string, and formation. As for numerical scheme of this strongly coupled model, the advection upstream splitting model (AUSMV) hybrid scheme is adapted for solving flow equations, while the finite difference approach is adapted for simultaneously solving energy conservation equations of the wellbore-formation system. Physical properties of gas and liquid phases are updated at each timestep. Predicted temperature and pressure distributions are validated against the field data. Flow behaviors predicted by the models with and without the heat transfer effect are compared. The effects of some major parameters (reservoir pressure, choke pressure, geothermal gradient, liquid mass flow rate) on temperature, pressure, and gas fraction distributions along the wellbore are investigated.

The Interstellar Medium Properties of Heavily Reddened Quasars & Companions at z ∼ 2.5 with ALMA & JVLA

We study the interstellar medium (ISM) properties of three heavily reddened quasars at $z\sim2.5$ as well as three millimetre-bright companion galaxies near these quasars. New JVLA and ALMA observations constrain the CO(1-0), CO(7-6) and [CI]$^3$P$_2-^3$P$_1$ line emission as well as the far infrared to radio continuum. The gas excitation and physical properties of the ISM are constrained by comparing our observations to photo-dissociation region (PDR) models. The ISM in our high-redshift quasars is composed of very high-density, high-temperature gas which is already highly enriched in elements like carbon. One of our quasar hosts is shown to be a close-separation ($<$2 arcsec) major merger with different line emission properties in the millimeter-bright galaxy and quasar components. Low angular resolution observations of high-redshift quasars used to assess quasar excitation properties should therefore be interpreted with caution as they could potentially be averaging over multiple components with different ISM conditions. Our quasars and their companion galaxies show a range of CO excitation properties spanning the full extent from starburst-like to quasar-like spectral line energy distributions. We compare gas masses based on CO, CI and dust emission, and find that these can disagree when standard assumptions are made regarding the values of $\alpha_{\rm{CO}}$, the gas-to-dust ratio and the atomic carbon abundances. We conclude that the ISM properties of our quasars and their companion galaxies are diverse and likely vary spatially across the full extent of these complex, merging systems.

Revisiting the positive DC corona discharge theory: Beyond Peek's and Townsend's law

The classical positive Corona Discharge theory in a cylindrical axisymmetric configuration is revisited in order to find analytically the influence of gas properties and thermodynamic conditions on the corona current. The matched asymptotic expansion of Durbin and Turyn [J. Phys. D: Appl. Phys. 20, 1490–1495 (1987)] of a simplified but self-consistent problem is performed and explicit analytical solutions are derived. The mathematical derivation enables us to express a new positive DC corona current-voltage characteristic, choosing either a dimensionless or dimensional formulation. In dimensional variables, the current voltage law and the corona inception voltage explicitly depend on the electrode size and physical gas properties such as ionization and photoionization parameters. The analytical predictions are successfully confronted with experiments and Peek's and Townsend's laws. An analytical expression of the corona inception voltage φon is proposed, which depends on the known values of physical parameters without adjustable parameters. As a proof of consistency, the classical Townsend current-voltage law I=Cφ(φ−φon) is retrieved by linearizing the non-dimensional analytical solution. A brief parametric study showcases the interest in this analytical current model, especially for exploring small corona wires or considering various thermodynamic conditions.

Effects of sub-Tg cross-linking of triptycene-based polyimides on gas permeation, plasticization resistance and physical aging properties

Two triptycene-based diamines, 2,6-diaminotriptycene and 2,6-diaminotriptycene- 14-carboxylic acid, were synthesized and reacted with 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to form three polyimides, denoted as 6FDA-DAT, 6FDA-DAT/DATCA (9:1) and 6FDA-DAT/DATCA (8:2). The last two carboxylic acid containing polyimides were further heated at a temperature range of 200–450 °C to induce decarboxylation crosslinking. Properties including solubility, thermal stabilities, glass transition temperature (Tg), d-spacing, physical aging and gas permeation were measured. Since Tg of 6FDA-DAT/DATCA (9:1) and 6FDA-DAT/DATCA (8:2) were not observable at temperature up to 450 °C, all decarboxylation crosslinking reactions were carried out below their Tgs. Gas permeabilities of 6FDA-DAT/DATCA (9:1) and 6FDA-DAT/DATCA (8:2) increased with decreased selectivities after crosslinking. No plasticization were observed for crosslinked 6FDA-DAT/DATCA (9:1) and 6FDA-DAT/DATCA (8:2) at a CO2 pressure up to 30 atm for pure gas and a partial CO2 pressure up to 20 atm for (CO2:CH4 1:1) mixed gases. In addition, crosslinked polymers exhibited significantly reduced physical aging rate. Therefore, the sub-Tg decarboxylation crosslinked polyimides had great potential for natural gas separation.

Mapping UV properties throughout the Cosmic Horseshoe: lessons from VLT-MUSE

We present the first spatially-resolved rest-frame UV study of the gravitationally lensed galaxy, the 'Cosmic Horseshoe' (J1148+1930) at z=2.38. Our gravitational lens model shows that the system is made up of four star-forming regions, each ~4-8 kpc^2 in size, from which we extract four spatially exclusive regional spectra. We study the interstellar and wind absorption lines, along with CIII] doublet emission lines, in each region to investigate any variation in emission/absorption line properties. The mapped CIII] emission shows distinct kinematical structure, with velocity offsets of ~+/-50 km/s between regions suggestive of a merging system, and a variation in equivalent width that indicates a change in ionisation parameter and/or metallicity between the regions. Absorption line velocities reveal a range of outflow strengths, with gas outflowing between -200<v(km/s)<-50 relative to the systemic velocity of that region. Interestingly, the strongest gas outflow appears to emanate from the most diffuse star-forming region. The star-formation rates remain relatively constant (~8-16 M_sol/yr), mostly due to large uncertainties in reddening estimates. As such, the outflows appear to be 'global' rather than 'locally' sourced. We measure electron densities with a range of log(Ne)=3.92-4.36 cm^-3, and point out that such high densities may be common when measured using the CIII] doublet due to its large critical density. Overall, our observations demonstrate that while it is possible to trace variations in large scale gas kinematics, detecting inhomogeneities in physical gas properties and their effects on the outflowing gas may be more difficult. This study provides important lessons for the spatially-resolved rest-frame UV studies expected with future observatories, such as JWST.

Адаптация степени черноты продуктов сгорания топлив к интервалу температур 1000…2000 К

The accuracy of calculations of heat transfer caused by the emission from a high-temperature gas flow during the combustion of natural fuels significantly depends on the accuracy and representation of data on thermal and physical properties of gases, as well as the value of a radiant heat flux. Th reliable experimental data helped to generate the dependencies that allow performing calculations of emissivity factor for combustion products. The accuracy of the calculable approximation of experimental data in the two-factor function – optical density of the gas and its temperature - has been determined. The adaptation of parameters in a ratio for calculating the attenuation ratio and the Buger number has been carried out based on the updated experimental data. The range of application of the obtained results for the intense combustion zone as well as for the main combustion chamber volume of a boiler unit has been considered. This gives the possibility to determine boundary conditions for these zones of the boiler unit. Previously developed mathematical model with a triple-component pattern, which allows dividing the influence of flare continuum and combustion gases, is applicable for the intense combustion zone. The heat transfer in the main combustion chamber volume is described within the heat transfer paradigm, which allows accounting for the configuration of the combustion chamber as well as the efficiency of heat emission to the waterwall surfaces.

GASP. VIII. Capturing the Birth of a Tidal Dwarf Galaxy in a Merging System at z ∼ 0.05

Abstract Within the GAs Stripping Phenomena in galaxies with MUSE (GASP) sample, we identified an ongoing 1:1 merger between 2 galaxies and the consequent formation of a tidal dwarf galaxy (TDG). The system is observed at z = 0.05043 and is part of a poor group. Exploiting the exquisite quality of the Multi Unit Spectroscopic Explorer (MUSE)/Very Large Telescope data, we present the spatially resolved kinematics and physical properties of gas and stars of this object and describe its evolutionary history. An old (luminosity weighted age ∼2 × 109 yr), gas-poor, early-type-like galaxy is merging with a younger (luminosity weighted age ∼2.5 × 108 yr), gas-rich, late-type galaxy. The system has a quite strong metallicity gradient, which is indicative of an early-stage phase. Comparing the spatial extension of the star formation at different epochs, we date the beginning of the merger between 2 × 107 yr &lt; t &lt; 5.7 × 108 yr ago. The gas kinematic pattern reflects that of the late-type object and is distorted in correspondence to the location of the impact. The stellar kinematic instead is more chaotic, as expected for mergers. The gas redistribution in the system induces high levels of star formation between the two components, where we indeed detect the birth of the TDG. This stellar structure has a mass of ∼6 × 109 M ⊙, a radius of ∼2 kpc, and even though it has already accreted large quantities of gas and stars, it is still located within the disk of the progenitor, is characterized by a high velocity dispersion, indicating that it is still forming, is dusty, and has high levels of star formation (star formation rate ∼ 0.3 M ⊙ yr−1). This TDG is originated in an early-stage merger, while these structures usually form in more evolved systems.

The effect of cross-linkers with multi-armed structures on gas transport properties in star-like poly (ethylene oxide) polymers

ABSTRACTFour series of star-like poly (ethylene oxide) have been prepared by incorporating the cross-linkers with tri-reactive cores, tetra-reactive cores, penta-reactive cores, and hexa-reactive cores, respectively. Chemical characterization was performed by Fourier transform infrared spectroscopy. The thermal properties were evaluated by differential scanning calorimetry. The average chain-to-chain distance in polymers was investigated by wide-angle X-ray diffraction. The effect of incorporating the cross-linkers with various reactive cores and multi-arms on the gas transport properties was reported. The relationship between the gas transport properties and physical properties was also discussed. Some of these polymers exhibit outstanding permeation–separation performance for CO2/N2, exceeding the CO2/N2 Robeson upper-bound line.

REMOVED: Simulation of steady flow of natural gas in a subsea flexible riser with heat exchange

Abstract Flexible riser technology is widely used in today's offshore industry. Evaluating pressure, temperature and velocity profiles in a subsea riser or a flexible pipe is essential in the design of a gas transfer system. Conventional pipeline correlations fail to give an acceptable accuracy for sizing, design and flow assurance applications of flexibles. Hence, availability of a rather simple computational model, which can give results with acceptable accuracy is highly advantageous. The aim of this article is to present a simple numerical method which can be used efficiently to accomplish this goal. A one dimensional finite difference method is used where the riser length is discretized into small segments. Natural gas physical and transport properties are calculated in each segment and flow equations in addition to a state equation are solved simultaneously to find the velocity, pressure and temperature profiles in the flexible riser. The Lee-Kesler corresponding states EOS has been used as the state equation. Mathcad™ has been applied for solving equations. The ability of the model to predict thermodynamic properties of natural gas has been compared with experimental data. Furthermore, friction and heat transfer models for a smooth and rough bore riser have been analyzed. For a rough bore riser with carcass corrugations, selecting a reasonable value for the equivalent sand grain roughness has been found to be crucial. The authors have also found the Joule-Thomson effect to be decisive in temperature change for a high pressure rough bore flexible gas riser subject to high pressure drop.

2D profiles of CO2, CH4, N2O and gas diffusivity in a well aerated soil: measurement and Finite Element Modeling

Soil gas fluxes depend on soil gas concentrations and physical properties of a soil. Taking soil samples for physical analysis into the laboratory strongly modifies soil gas concentrations and also cuts roots that sustain the activity in the rhizosphere. Since microbial processes interact with gas concentrations in soil, we need to study gas transport and production in situ.We developed a method to monitor the transport and production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in soils in situ in a two dimensional (2D) profile using tetrafluoromethane (CF4) and sulfur hexafluoride (SF6) as tracer gases and Finite Element Modeling of soil gas transport. Continuous injection of the inert tracer gases and 2D gas sampling in a soil profile allowed for inverse modeling of the 2D profile of soil gas diffusivity. In a second step, the 2D profiles of the production and consumption of CO2, CH4, and N2O were inversely determined.Soil gas concentrations were monitored in a Scots pine stand in South-West Germany during a rain-free week in the fall. The 2D relative (so as to be independent of gas species) soil gas diffusivity profile showed large horizontal variability. Relative soil gas diffusivity was found to be anisotropic with the vertical direction greater by a factor of 1.26. Topsoil moisture decreased slowly over time resulting in an increase in relative soil gas diffusivity. The soil was found to be a source of CO2, and a net sink of CH4 and N2O, with the highest production (CO2) and consumption (CH4, N2O) occurring in the topsoil. The gas concentration and production profiles of CO2 were nearly horizontally homogenous, while those for CH4 showed larger horizontal differences. Net consumption of CH4 and net production of CO2 both increased as the soil dried. This occurred despite reverse trends for these variables in the topsoil (0–8cm depth) which were more than offset by the underlying soil becoming more active. Sensitivity tests showed that the determination of 2D profiles of soil gas diffusivity and production and consumption of CO2 and CH4 were more reliable than the estimates for N2O because the magnitudes of these for N2O were very low. Our method represents a useful tool for the analyses of soil gas flux heterogeneities and associated microbial processes within soil profiles.

Studying the operation of a VVER steam generator in the condensing mode at different parameters of emergency processes

The article presents the results of the experimental study of heat and mass transfer processes in an NPP steam generator during the operation of passive safety systems of new-generation VVER reactor installations. At the GE2M-PG test rig in the Leypunsky Institute for Physics and Power Engineering, two series of experiments corresponding to different stages of the accident were completed. In these experiments, the performance of VVER steam generator in the condensing mode with and without the removal of gas-vapor mixture from the “cold” header has been studied. As a result of the first series of experiments, it was found that, for any of the parameters of the emergency process, the steam generator’s power does not drop below 80% of the original value. Furthermore, we revealed that the composition and physical properties of gases in the investigated concentration range did not notably affect the processes in the steam generator. In the second series of experiments without removal of noncondensable gases, the influence of parameters of the emergency process on the efficiency of heat transfer in the steam generator operating in the condensing mode was investigated. In order to study the heat transfer processes, we studied the change of the temperature difference between the media of the first and second circuits in our experiments. We found that the value of the temperature difference depends on both the mass of noncondensable gases accumulated in the tube bundle and their accumulation rate. The accumulation rate is determined by the power of the steam generator and the concentration of gases entering the steam generator. As a result of the analysis of experimental data, we obtained the analytical dependence reflecting change in the power of the steam generator operating in the emergency condensing mode.

充气硬盘磁头滑块飞行特性影响因素研究

为了减小磁盘高速旋转所承受的气体阻力、降低硬盘内部结构所承受的气流冲击和振动、以及提高硬盘存储密度和工作稳定性，人们正考虑向硬盘内部填充低密度气体。充气硬盘还具有存储容量大、节能、散热性能好等优点。硬盘工作过程中，磁头滑块飞行特性(承载力W、压力中心Xc和Yc)对硬盘工作稳定性有着重要影响。本文研究了充气气体物理特性、表面粗糙度、磁盘转速、飞行高度和俯仰角对硬盘磁头滑块飞行特性的影响，研究结果发现：磁盘转速的增加、飞行高度的降低、俯仰角的减小和氦气在氦气–空气混合气体中的比重(不同气体物理特性)下降，都会导致磁头滑块承载力的增加；磁盘转速的增加、飞行高度的增加、俯仰角的减小，都会导致压力中心Xc的减小；对于不同的磁盘转速、飞行高度、俯仰角、氦气在氦气–空气混合气体中的比重，压力中心Yc都几乎保持不变；粗糙度高度(σ)对承载力、压力中心Xc和Yc的影响，在不同粗糙度方向(γ)时，呈现出不同的影响规律。 In order to reduce the gas resistance of the high speed rotating disk and the impact and vibration of internal structure in a hard disk drive (HDD), and improve the storage density and working stability of a HDD, some kinds of gases with a low density are considered to fill inside a sealed HDD. The filled-gas HDD has some advantages of a large capacity, energy saving and heat dissipation performance. In an operating HDD, the flying characteristics of the slider, including the bearing capacity W, the pressure center Xc and Yc, have an important effect on the working stability of the HDD. In present paper, the effects of the gas physical properties filled inside the HDD, surface roughness, disk rotational speed, flying height and pitch angle, on flying characteristics of the slider, are studied. The results show that the W of the slider increases with the increase of the disk rotational speed, the decrease of the flying height, the decrease of the pitch angle and the decrease of proportion of helium gas in a mixed gas. The Xc decreases with the increase of the disk rotational speed, the increase of flying height, the decrease of the pitch angle. For different disk rotational speed, flying height, pitch angle, and proportion of helium gas in a mixed gas, the Yc keeps almost unchanged. For different direction of roughness (γ), the roughness height (σ) has different effect on W, Xc and Yc.

Exocometary gas structure, origin and physical properties around β Pictoris through ALMA CO multitransition observations

Recent ALMA observations unveiled the structure of CO gas in the 23 Myr old β Pictoris planetary system, a component that has been discovered in many similarly young debris discs. We here present ALMA CO J = 2−1 observations, at an improved spectro-spatial resolution and sensitivity compared to previous CO J = 3−2 observations. We find that (1) the CO clump is radially broad, favouring the resonant migration over the giant impact scenario for its dynamical origin, (2) the CO disc is vertically tilted compared to the main dust disc, at an angle consistent with the scattered light warp. We then use position-velocity diagrams to trace Keplerian radii in the orbital plane of the disc. Assuming a perfectly edge-on geometry, this shows a CO scaleheight increasing with radius as R0.75, and an electron density [derived from CO line ratios through non-local thermodynamic equilibrium (NLTE) analysis] in agreement with thermodynamical models. Furthermore, we show how observations of optically thin line ratios can solve the primordial versus secondary origin dichotomy in gas-bearing debris discs. As shown for β Pictoris, subthermal (NLTE) CO excitation is symptomatic of H2 densities that are insufficient to shield CO from photodissociation over the system's lifetime. This means that replenishment from exocometary volatiles must be taking place, proving the secondary origin of the disc. In this scenario, assuming steady state production/destruction of CO gas, we derive the CO+CO2 ice abundance by mass in β Pic's exocomets to be at most ∼6 per cent, consistent with comets in our own Solar system and in the coeval HD181327 system.

Natural gas sorption evaluation on microporous materials

In this work, detailed comparisons of the natural gas (NG) mixture adsorption capacity, cycling stability and physical properties of ten microporous samples were conducted. The BET specific surface area and micropore volume of the adsorbents are shown to correlate to their maximum excess NG adsorption capacity at 298 K and up to 70 bar, irrespective of the chemistry and functionalities of the materials. The cycling stability highly depends on the material's pore size and pore size distribution. A narrow pore size distribution with an optimum pore width of 8–11 Å is known to improve the maximum excess methane adsorption. However, when considering NG blends containing components with higher binding energies and slower diffusion rates than methane, we show that large micropores and even mesopores are necessary to provide easy diffusion paths for the adsorbate molecules to be desorbed from and diffuse out of the pore network. Pores which are too small, e.g. < 5 Å, are not desired since it's highly possible that the large species can be trapped in, resulting in a decrease in storage capacity with cycling. Adsorbent tailoring and development for NG storage applications appears to be sensibly different than for pure methane.

Instabilities due to turbulence through inlet jet in plunging jet bubble column

Bubble columns, where the liquid is in the continuous phase and the gas phase is on the form of dispersed bubbles, are widely utilised in many industrial applications. When designing these bubble columns it is important to be able to predict the conditions that mark the transition from homogeneous (bubbly) to heterogeneous (churn-turbulent) flow. The transition is a function of many variables, including: liquid and gas superficial velocities, bubble diameter, and liquid and gas physical properties. Linear stability analysis (LSA) has been successfully applied by many researchers to determine the gas volume fraction at which the instability takes place; and correspondingly a one dimensional stability factor, f1, has been proposed (see for example Joshi et al. (2001)). Briefly, the LSA analysis utilises the velocity fluctuations of both the dispersed and continuous phases associated with the specific energy dissipation rate of the two phase mixture. Typically, the specific energy dissipation rate is correlated with the density of the bed. The previous analysis, however, does not consider the energy input which associated with the turbulence intensity (velocity fluctuations) of the incoming liquid stream. Usually, this component can be ignored in sparged bubble columns because its magnitude is relatively small and it also decays in the axial direction. In plunging liquid jet bubble columns the liquid is introduced as a high speed jet that entrains gas which is then broken into fine bubbles in the Mixing Zone. The bubby mixture then passes into the Two Phase Flow Zone where instabilities can be generated. The Mixing Zone is a region of high energy dissipation resulting in relatively large liquid velocity fluctuations, which can directly influence the instability of the Two Phase Flow Zone.In this study the existing linear stability analysis is modified to include the influence of inlet liquid velocity fluctuations on the stability parameter, f1. The modified theory is applied to the previous work of Evans (1990) for a plunging liquid jet bubble column to determine the critical gas volume fraction at which transition takes place in the Two Phase Flow Zone. In order to apply the model, drift-flux analysis has been used to obtain bubble diameter as a function of gas and liquid superficial velocities, and computational fluid dynamics has been utilised to quantify the velocity fluctuations of the liquid exiting the Mixing Zone.

High performance post-modified polymers of intrinsic microporosity (PIM-1) membranes based on multivalent metal ions for gas separation

Novel post-modified polymers of intrinsic microporosity (PIM-1) membranes with cross-linkages formed through multivalent metal ions have been prepared. Structural characterization was performed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS). The cross-linking effect on gel content of the membrane was determined. The thermal property was evaluated by thermo-gravimetric analysis (TGA). The average chain-to-chain distance of the polymer was investigated by wide-angle X-ray diffraction (WAXD). The O2, N2, CH4 and CO2 gas transport properties of post-modified PIM-1 membranes were reported. The relationship between gas transport property and physical properties was also discussed. Compared with original PIM-1 membrane, the post-modified PIM-1 membranes display higher gas selectivity for O2/N2, CO2/N2 and CO2/CH4 with a corresponding decrease in gas permeability. The outstanding permeation-separation performance for CO2/CH4 exceeds the Robeson upper-bound line. The post-modified PIM-1 membranes display a potential application for industrial-scale CO2/CH4 separation. In addition, it is probably that the incorporation of multivalent metal ions can expand the applicable scope of PIM-1 membrane.

Novel models on fluid’s variable thermo-physical properties for extensive study on convection heat and mass transfer

Our novel models for fluid’s variable physical properties are improved and reported systematically in this work for enhancement of theoretical and practical value on study of convection heat and mass transfer. It consists of three models, namely (1) temperature parameter model, (2) polynomial model, and (3) weighted-sum model, respectively for treatment of temperature-dependent physical properties of gases, temperature-dependent physical properties of liquids, and concentration- and temperature-dependent physical properties of vapour-gas mixture. Two related components are proposed, and involved in each model for fluid’s variable physical properties. They are basic physic property equations and theoretical similarity equations on physical property factors. The former, as the foundation of the latter, is based on the typical experimental data and physical analysis. The latter is built up by similarity analysis and mathematical derivation based on the former basic physical properties equations. These models are available for smooth simulation and treatment of fluid’s variable physical properties for assurance of theoretical and practical value of study on convection of heat and mass transfer. Especially, so far, there has been lack of available study on heat and mass transfer of film condensation convection of vapour-gas mixture, and the wrong heat transfer results existed in widespread studies on the related research topics, due to ignorance of proper consideration of the concentration- and temperature-dependent physical properties of vapour-gas mixture. For resolving such difficult issues, the present novel physical property models have their special advantages.

Techniques for Natural Gas Physical Properties Definition for Flow Rate and Volume Metering Systems

Techniques for Natural Gas Physical Properties Definition for Flow Rate and Volume Metering Systems

A similarity transformation of velocity field and its application for an in-depth study on laminar free convection heat transfer of gases

An innovative similarity transformation of velocity field is reported for equivalent transformation of governing partial differential equations of laminar free convection. To demonstrate its rationality theoretically, its rigorous theoretical derivation is presented firstly in this work. On this basis, an example is presented with successful application for demonstration of its advantages in in-depth study on free convection heat transfer. The governing ordinary differential equations of laminar free convection equivalently transformed by the innovative similarity transformation are presented. It is seen that by the innovative similarity transformation the variable physical properties are transformed into the forms of the related physical property factors, which are organically coupled in the transformed governing ordinary differential equations. It proves that the innovative similarity transformation is very well suitable for consideration of variable physical properties. Then, a new algorithm is presented to calculate fluids flow and heat transfer of laminar free convection. It contains the theoretical and numerical models on laminar free convection, to consider the variable physical properties, to obtain the system of numerical solutions, and then, to create formalization equations for the convection heat transfer coefficient by means of an optimal curve-fitting approach based on the system of numerical solutions. A system of numerical calculations of the governing ordinary differential equations is presented for the gaseous laminar free convection. A temperature parameter model is induced for convenient and reliable treatment of variable physical properties of gases. The delivered formalization equations of heat transfer coefficient on gaseous free convection have strong theoretical and practical value for heat transfer applications because they are created based on the theoretically reasonable similarity transformation model combined with a better model of consideration of fluid's variable physical properties, accurate numerical solutions, and rigorous formalization equations combined with rigorous theoretical derivation. All these prove that the reported innovative similarity transformation is a better alternative applied for in-depth study on free convection heat transfer.