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The thermal‐hydraulic performance of printed circuit heat exchanger (PCHE) through an experimental vaporization process of supercritical nitrogen was investigated. The inlet temperature of supercritical nitrogen was controlled between 113 K and 129 K, while its pressure was controlled between 4.5 MPa and 6 MPa. The mass of supercritical nitrogen corresponds to the turbulent state on the cold side of PCHE, which was maintained at 299.94 kg/h. A numerical processing of the same supercritical nitrogen flow through a single channel of PCHE cold side was presented. The numerical results were validated by comparison with the experimental data. Both experimental and numerical results showed that the increased inlet supercritical nitrogen pressure improved the heat transfer performance and pressure drop decreased with increasing the pressure at the PCHE cold side. Furthermore, the Fanning friction coefficient (f) and the Nusselt number (Nu) of supercritical nitrogen flow obtained by numerical simulation and empirical correlation were compared.

Although direct application of anhydrous ammonia (NH₃) is a common practice for Midwestern corn (Zea mays L.) production in the USA, field studies utilizing ¹⁵N to quantify nitrogen (N) uptake efficiency have long been impeded by the difficulties and safety hazards inherent to a liquified gas that must be handled and applied under pressure. A manifold system is described for transferring known quantities of NH₃ from labeled and unlabeled sources to obtain a desired ¹⁵N enrichment, and for collecting the mixture cryogenically in a tank specifically configured for knifed applications using a tractor-mounted tool bar. Enrichments of 1.2 to 1.5 atom% ¹⁵N were obtained for 3 kg of NH₃ prepared within a normal working day by a 15-fold dilution with 10 atom% ¹⁵N as the starting label. A collection capacity of such magnitude represents a 3000% upscaling over systems previously described for this purpose, providing an essential prerequisite for field plot research to realistically assess the fate and fertilizer value of anhydrous NH₃.

Author(s): Oldenburg, C; Pan, L; Zhou, Q; Dobeck, L; Spangler, L | Abstract: Carbon dioxide (CO 2 ) extraction from deep reservoirs is currently important in CO 2 enhanced oil recovery (EOR) and may become more important in the future if interim CO 2 storage becomes common. In late 2014, we were involved in a production test of liquid CO 2 from the Middle Duperow dolostone at Kevin Dome, Montana. The test resulted in lowering the temperature at the well bottom to ∼2 °C, and showed that the well and reservoir had very low CO 2 productivity. We have used the CO 2 modeling capabilities of the TOUGH codes to simulate the test and to show that liquid CO 2 in the reservoir changes to gas phase as the pressure is lowered in the well during production testing. The associated phase change and decompression combine to drastically lower the bottom-hole temperature, creating the potential for water ice or CO 2 hydrate to form. By hypothesizing a relatively high-permeability damage zone near the well surrounded by lower permeability reservoir rock, we can match the observed pressure, temperature, and production rate. Moving from the Kevin Dome test to the question of CO 2 extraction from deep reservoirs in general, we carried out a parametric study to investigate the effects of reservoir depth and transmissivity on CO 2 production rate for a prototypical reservoir. Simulations show that depth and high transmissivity favor productivity. Complex phase changes within the ranges of P-T encountered in typical CO 2 production wells affect production rates. The results of our parametric study may be useful for the preliminary feasibility assessment of CO 2 extraction from deep reservoirs. © 2019 Society of Chemical Industry and John Wiley a Sons, Ltd.

Choline chloride + phenylacetic acid-based deep eutectic solvents are studied. Their most relevant experimental physicochemical properties at different mixing ratios together with the CO2 solubility data obtained in wide pressure and temperature ranges are reported. The presented materials exhibit a significant CO2 capture performance with low corrosion effect when compared with the most common amine-based CO2 capture agents. Detailed rheological measurements are carried out and various models are applied to describe the dynamic flow behavior of the solvents. The CO2 absorption mechanism is evaluated by studying the behavior of the liquid gas and interface. Due to the advantages of low cost, nontoxicity, and favorable physical properties, these solvents are an environmentally promising alternative for effective CO2 capture technological applications. This work was funded by the NPRP grant No. 6-330-2-140 from the Qatar National Research Fund, being a member of Qatar Foundation, and by the Ministerio de Economa y Competitividad (Spain, project CTQ2013-40476-R). The authors have declared no conflict of interest. Scopus

An electrical resistance tomography (ERT) linear probe was used to measure gas hold-up in a two-phase (gas–liquid) and three phase (gas–solid–liquid) stirred-tank system equipped with a Rushton turbine. The ERT linear probe was chosen rather than the more commonly used ring cage geometry to achieve higher resolution in the axial direction as well as its potential for use on manufacturing plant. Gas-phase distribution was measured as a function of flow regime by varying both impeller speed and gas flow rate. Global and local gas hold-up values were calculated using ERT data by applying Maxwell's equation for conduction through heterogeneous media. The results were compared with correlations, hard-field tomography data, and computational fluid dynamic simulations available in the literature, showing good agreement. This study thus demonstrates the capability of ERT using a linear probe to offer, besides qualitative tomographic images, reliable quantitative data regarding phase distribution in gas–liquid systems.

The thermal lens technique is applied to vibrational overtone spectroscopy of cryogenic solutions of benzene. The pump and probe thermal lens technique has been found to be very sensitive for detecting samples of low concentration in transparent liquefied gas solvents at low temperatures. The C–H fifth vibrational (Δυ = 6) overtone of benzene in liquefied ethane, krypton, and argon have been recorded at concentrations between 10 and 58 p.p.m. in a range of temperatures between 87 and 150 K. Experiments with one-color laser excitation are sensitive enough to detect benzene at parts per million mole fraction. The dependence of the signal on the physical properties of the solvent and the excitation wavelength are shown. Finally, a thermal lens experiment with two-color laser excitation is presented showing an increase in the magnitude of the peak absorption that will result in an increase of the limit of detection. A three-level model to explain signal enhancement with respect to one-color laser excitation under the same experimental conditions is presented. Copyright © 2015 John Wiley & Sons, Ltd.

Numerical solvers based on population balance equations (PBE) coupled with flow equations are a promising approach to simulate liquid/gas-liquid dispersed flows, which are very commonly observed in nature and in industrial processes. The challenges for the numerical solution of the coupled equation systems are discussed and detailed numerical recipes are presented whose main ingredients are the method of classes, positivity-preserving linearization and the high-order FEM-AFC schemes, additional to the FeatFlow in-house flow solver package. Liquid-liquid flows through static mixers and dispersed phase systems in a flat bubble column are studied with the accordingly developed computational tool. The suggested recipes were validated by comparing the numerical results against experimental data.

This article shows that spray nozzles pulsations can greatly improve the distribution of the sprayed liquid on fluidised bed particles, as characterised by a Nozzle Performance Index (NPI). Appropriate pulsations increased the NPI by nearly 100% under several operating conditions. This article compares four pulsating, gas atomised nozzles under various operating conditions. The performance of each nozzle was evaluated by measuring the electric conductance of a bed of silica sand particles fluidised by air, subsequent to liquid injection. Three sets of experiments were conducted to investigate the effect of operating conditions on the performance of the four gas atomised nozzles. The first set determined the effect of the liquid flowrate, the second set measured the effect of a restriction orifice on the atomisation gas line and the third set studied the effect of the atomisation air to liquid ratio. Artificial nozzle spray pulsations were found to have similar beneficial effects with the different types of gas-atomised nozzles. © 2011 Canadian Society for Chemical Engineering

An accurate finite-volume-based numerical method for the simulation of an isothermal two-phase flow, consisting of a liquid slug translating in a non-reacting gas in a circular pipe is presented. This method is built on a sharp interface concept and developed on an Eulerian Cartesian fixed-grid with a cut-cell scheme and marker points to track the moving interface. The unsteady, axisymmetric Navier–Stokes equations in both liquid and gas phases are solved separately. The mass continuity and momentum flux conditions are explicitly matched at the true surface phase boundary to determine the interface shape and movement. A quadratic curve fitting algorithm with marker points is used to yield smooth and accurate information of the interface curvatures. It is uniquely demonstrated for the first time with the current method that conservation of mass is strictly enforced for continuous infusion of flow into the domain of computation. The method has been used to compute the velocity and pressure fields and the deformation of the liquid core. It is also shown that the current method is capable of producing accurate results for a wide range of Reynolds number, Re, Weber number, We, and large property jumps at the interface. Copyright © 2010 John Wiley & Sons, Ltd.

Compared with inorganic chemical heat pumps (CHPs), organic liquid-gas CHPs are more amenable to be run as a continuous process because the reactants and products can be fed or removed continuously. Therefore, increasing attention has been paid to investigations of CHPs using the organic liquid-gas reaction system. Relevant research topics involved reaction catalyst, chemical reaction kinetics, reactive distillation, energy efficiency evaluation, economic analysis, etc. Nevertheless, the research on an organic liquid-gas CHP system is still in the elementary stage. A detailed review on the current research status of catalyst-assisted CHPs employing an organic liquid-gas reaction system has been performed. Existing problems are identified and future research directions are proposed.

The application of wet biomass in energy conversion systems is challenging, since in most conventional systems the biomass has to be dried. Drying can be very energy intensive especially when the biomass has a moisture content above 50 wt.% on a wet basis. The combination of hydrothermal biomass gasification and a solid oxide fuel cell (SOFC) gas turbine (GT) hybrid system could be an efficient way to convert very wet biomass into electricity. Therefore, thermodynamic evaluation of combined systems with hydrothermal gasification units and SOFC–GT hybrid units has been performed. Three hydrothermal gasification cases have been evaluated; one producing mainly methane, a second one producing a mixture of hydrogen and methane and the last one producing mainly hydrogen. These three gasification systems have been coupled to the same SOFC–GT hybrid system. All the integrated systems have electrical exergy efficiencies around 50%, therefore, the combination of supercritical water gasification and SOFC–GT hybrid systems seems promising. The overall system performance depends for a large part on the liquid gas separation. Further research is required for finding out the optimal separation conditions.

Gas-liquid/gas-liquid-solid systems are widely used in the chemical process industry for a variety of applications. In the present work, we have characterized the dynamics of gas-liquid/gas-liquid-solid flows in cylindrical bubble columns using experiments and CFD simulations. The low frequency oscillations corresponding to the local re-circulatory flow were characterized using wall pressure fluctuation measurements. Eulerian-Eulerian two-/three-phase simulations were carried out with a focus on characterizing the dynamic properties of gas-liquid/gas-liquid-solid flows. The effects of superficial gas velocity, H/D ratio and solid loading on the dynamic and time-averaged flow behavior were studied experimentally and computationally. The simulated results were compared with the experimental measurements. The results presented are useful for understanding the dynamics of gas-liquid/gas-liquid-solid flows in bubble columns and provide a basis for further development of CFD models for three-phase systems.

The effects of air-flow pulsation and water and air flowrates on the hydrodynamics of liquid—gas and three-phase fluidized beds containing 3-mm glass beads have been studied in a 90-mm i.d. column. Under steady-flow conditions, both types of bed contained a relatively large number of small bubbles. With a pulsing air flow, however, a smaller number of much larger bubbles or slugs were formed. This was attributed to different mechanisms of bubble formation at the distributor. Variations in phase holdup were explained in terms of the effects of the operating parameters on the bubble characteristics. On a etudie dans une colonne de 90 mm de diametre interieur les effets de la pulsation air-ecoulement et des debits d'eau et d'air sur l' hydrodynamique de lits fluidises gaz—liquide et triphasiques contenant des billes de verre de 3 mm. Dans des conditions d'ecoulement en regime permanent, les deux types de lit contenaient un nombre relativement important de petites bulles. Toutefois, avec un ecoulement a air pulse, il s 'est forme un moins grand nombre de bulles de tres grande dimension ou de bouchons. Ceci est imputable aux differents mecanismes de formation des bulles au niveau du distributeur. Les variations dans la retention des phases sont expliquees par les effets des parametres operatoires sur les caracteristiques des bulles.

This paper describes a microvalve to control liquefied gas in a micro fuel reforming system. To realize both high pressure leak tolerance and low pressure loss, a main valve is pneumatically actuated by the pressure of the liquefied gas itself, and its pneumatic actuation is controlled by two electrostatic sub-valves. The fabricated microvalve was tested in terms of pressure loss in the open state, leakage in the closed state, driving voltage, and response time. The pressure loss was close to the theoretical value, which was sufficiently low for the application. The apparent leakage was not detected until the input pressure reached 150 kPa (gage). The driving voltage of the sub-valve was 30-40 V. The response time from the closed to the open state is expected to be less than 200 ms. The experimental results suggest that all the required functions such as low pressure loss, electrostatic actuation and leak proof operation can be realized. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

BACKGROUND: Ejectors have excellent mass transfer characteristics with energy efficiency and can be used in place of conventional countercurrent systems, namely, packed bed contactors as well as venturi scrubbers, cyclones and airlift pumps. Although a number of papers have been published in the recent past, none of them provides a theoretical basis for the prediction of gas phase holdup. In this work an attempt has been made to develop a theoretical basis for predicting gas phase holdup based on first principles using Nguyen and Spedding's distribution function (Co) and initial value parameter (B). RESULTS: In the present work, measurements and correlations are reported for the gas holdup and energy dissipation in a liquid-gas ejector. The holdup data have been correlated using the theoretical models proposed by Nguyen and Spedding,26 with an estimated initial value parameter B and the distribution function Co. The throat and diffuser loss coefficients were found to be constant up to a gas/liquid flow ratio of 1.6 and then it was found to be a function of area ratio, physical properties and gas holdup. CONCLUSIONS: The present proposed correlations for gas phase holdup and energy dissipation, Emix, should be useful for the efficient design of co-current ejectors for gas-liquid contacting, in particular for the removal of CO2 from natural gas, since the viscosity and surface tension ranges covered in the present study are essentially those encountered in amine–carbon dioxide systems. Copyright © 2008 Society of Chemical Industry

The 2006 edition of NFPA 52 Vehicular Fuel Systems Code addresses natural gas and hydrogen storage and refueling safety. Specifically, this document addresses the issues of: Gas and liquefied gas storage Vehicle-dispensing operations Gas piping System siting System maintenance This article describes the hazards associated with the operations listed and how the code sets requirements to mitigate these hazards. This document, which was initially issued in 1984, is the first edition of NFPA 52 that addresses hydrogen systems. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2007

This article describes what is probably the largest application of a moire technique. Real time video systems and a remotely controlled, high quality still camera were used to monitor the buckling in the walls of a liquid gas storage tank, in a section more than 30 m across.

The extraction of 15 aroma compounds from a highly diluted aqueous feed with hollow fiber membrane contactors was investigated. Membrane-Based Solvent Extraction (MBSE) and Membrane Air-Stripping (MAS) were tested with the aqueous feed crossflowing on the shell side and the stripping phase flowing in the lumen of the hollow fiber. Experimental results showed that globally, MBSE offered higher overall mass transfer coefficients than MAS. This difference was mainly explained by the gap in partition coefficients. Hexane-water partition coefficients were about 10,000 times higher than air-water partition coefficients. The contribution of each local resistance to mass transfer was identified by a resistance-in-series model. Mass transfer in the aqueous feed boundary layer is the limiting step in MBSE, while mass transfer in the stripping gas boundary layer is the limiting step in MAS. A diagnostic tool based on partition coefficients was developed in order to help choose the adequate process for the extraction of an aroma compound.

This paper presents the extension of a high-resolution conservative scheme to the one-dimensional one-pressure six-equation two-fluid flow model. Only mixtures of water and air have been considered in this study, both fluids have been characterized using simple equations of state, namely stiffened gas for the liquid phase and perfect gas for the gas phase. The resulting scheme is explicit and first-order accurate in space and time. A second-order version of the scheme has also been derived using the MUSCL strategy and slope limiters. Some numerical results show the good capabilities of this type of schemes in the solution of discontinuities in two-fluid flow problems, all of them are based on water/air numerical benchmarks widely used in the two-phase flow literature. Copyright © 2005 John Wiley & Sons, Ltd.

This study deals with the consequence analysis of an accidental release of chlorine from a storage tank in a chlor-alkali plant. Chlorine is a liquefied gas and is stored in tanks for various uses like the production of textiles, paper products, and so forth. Chlorine is highly toxic and if released accidentally has the potential to kill or injure people in the vicinity of the storage tank. Calculations are used to determine the discharge rate of chlorine in liquid phase, liquid–gas phase, and gas phase. Subsequently, dispersion calculations are used to determine the downwind concentrations in the vicinity of the tank. The probit equation is used to estimate fatalities for the various accident scenarios. These results are used to develop improvement needs and an emergency response plan. © 2012 American Institute of Chemical Engineers Process Saf Prog, 2012

Experimental liquid densities and compressibility factors of natural gas and liquefied natural gas mixtures were reproduced using an analytical equation of state, based on the statistical-mechanical perturbation theory of Weeks, Chandler and Andersen. The temperature-dependent parameters of the equation of state were calculated using our previous corresponding-states correlation, based on the normal boiling point parameters. This article shows that the equation of state for multicomponent natural gas and liquefied natural gas mixtures would be predictable with minimal input information, namely the normal boiling temperature and the liquid density at the normal boiling point. The calculated results agreed well with the experiment. From a total of 590 data points for natural gases and 203 data points for liquefied natural gases examined in this work, the average absolute deviations were 0.33% and 2.48%, respectively, and the maximum deviations were 2.63% and 4.61%, respectively.

An accident involving a two-phase release can result in serious consequences for people as well as the environment. Consequently, tools are needed to give accurate predictions of the discharge rate, physical state, composition of released material, and chocked pressure in order to improve process safety efficiency. This paper discusses possible approaches to the examination of two-phase critical releases and presents a slip equilibrium model which provides critical flow rate, critical pressure, and phase fraction of the two phases emerging from an accidentally broken pipe containing a liquefied gas mixture under pressure. Comparisons between experimental critical flow rates and model predictions are favorable in both monocomponent and multicomponent mixtures.

The C.E.A. (the French Atomic Energy Agency) has developed the A.T.C. plasma spray process (Atmosphere-and Temperature-Controlled process): a classical inert plasma spraying system is coupled with a cryogenic cooling of the substrate by liquefied gas atomization. This process alternately supplies positive and negative heat fluxes to the substrate. In order to quantify these fluxes, and to better control the process, a heat flux measurement system has been developed: under industrial conditions, several multi-layer sensors measure the flux received by the substrate. This paper presents the diagnostic apparatus and the first results measured in A.T.C. plasma spraying conditions. These results were obtained in dynamic operating conditions.

An experimental study was conducted to propose an adequate mathematical model for liquid-gas equilibrium in acetic acid fermentations. Three operation scales (laboratory, pilot plant, and industrial plant) were employed to obtain the sets of experimental data. The proposed model, based in the UNIFAC method for the estimation of activity coefficients of a solution consisting of several components, takes into account the effect of temperature. However, in the set of equations, it has been necessary to put in the degree of equilibrium (epsilon). This coefficient adequately reflects the physical conditions of fermentation equipment. The experimental and numerical results help to define the fundamental mechanisms for liquid-gas equilibrium in these systems and demonstrate the model validity in the three tested scales. It was also found that in an industrial setting, closed systems are those with lowest evaporation losses. Copyright 1998 John Wiley & Sons, Inc.

The storage of natural gas in other light hydrocarbons is one procedure for automotive natural gas usage that reduces the requirement of high-pressure or cryogenic storage. Model solutions of methane in n-butane, propane, and a liquefied-bottled-gas mixture were simulated using the Benedict-Webb-Rubin-Starling equation of state to determine the pressures necessary to maintain a liquid phase with perturbations in both temperature ({minus}1 C to 38 C) and mole fraction (50 to 80 mol% methane). Methane storage in these liquid solutions is between 45 and 93% of an equal tank volume of compressed natural gas (CNG) at 21 MPa and 15 C. The simulation results indicate that solutions of this type contain 40 to 67% of the energy of gasoline at pressures that range from 60 to 40% that of CNG at 21 MPa and 15 C.

Carbon dioxide or ethane was used as an antisolvent medium from which organic solids dissolved in a liquid carrier solvent are precipated and collected as finely divided solids. Solid compounds of pharmaceutical interest, which are virtually insolute in the supercritical fluids per se, are efficiently obtained by injecting a solution of the solid into a volume of stirred supercritical fluid or compressed liquefied gas. A free-flowing powder comprising very small particles ( > 5 μm) is obtained. Both continuous-flow and batch operations were developed although he continuous-flow operation is preffered. Process variable including temperature, pressure, stirring rate, injection concentration, and the rate and temperature of the carrier solution injection were studied to see how they affect the physical properties of the resultant product. Recovery (yield), particle size and uniformity, bulk powder density, microscopic apperance, and surface area were measured. Carbon dioxide and ethane antisolvents, several liquid-phase injection solvents, and different solid compunds were studied. A simple unsteady-state mathematical model of this CSTR precipitator is also presented.

The paper contains the results of new experimental measurements of the isochoric heat capacity and the liquid-gas coexistence curve of carbon dioxide in the one-phase region near the critical point. The measurements were performed in a high temperature adiabatic calorimeter used earlier for the determination of the isochoric heat capacity of several liquids and liquid mixtures near the critical points [1, 2]. The experiments have been performed at seven isochores, namely: 461.2, 464.5, 467.5, 470.1, 477.7, 499.0, and 509.8 kg·m−3 in the neighbourhood of the critical point and the coexistence curve. The measurements were made with samples of constant mass contained in a calorimeter vessel of nearly constant volume. Uncertainties of the heat-capacity measurements are estimated to be less than 2 percent far from Tc and 3 percent in the immediate vicinity of the critical point. The uncertainty in temperature was less than ±10 mK.

The loss of containment (LOC) for Pressure Liquefied Gas (PLG) vessels under accidential fire engulfment is shown to be very complex. The LOC depends upon: (i) the extent and intesity of external heating, (ii) the pressure relief device (PRD) operation and flare (if contents flammable), (iii) the fluid and fill level, (iv) the construction of the vessel, and (v) the thermohydraulic history of the commodity prior to failure. The Simple experiments described here shows that there exists a new type of more powerful failure than the BLEVE. This even we call a BLCBE, a Boiling Liquid Compressed Bubble Explosion. A hypothesis is advanced to explain this mode of failure which is supported by an initial series of small scale experiments involving Argon, water, R11, and R123. A comprehensive test program to determine the details of the BLCBE and BLEVE failure modes is indicated along with work to determine methods of protection.

Gas conversion to liquefied gas (LNG) and transport by LNG tankers is one option for meeting expanding gas consumption and for gas traded internationally. This paper examines the impact of the traditional gas contract provisions of indefinite pricing, market out price ceilings, and take-or-pay requirements on the profitability of LNG projects in the context of markets characterized by price and quantity uncertainty. Simulation experiments are used to examine and calibrate the effects of those provisions. The results provide guidance to operators, host countries and purchasers in structuring such contracts. The paper also assesses prospects of future expansion of world LNG capacity.

Liquid gases (LG), i.e. low boiling compounds with vapor pressures below 5 bar at room temperature, are introduced as solvents for trace analyses. A system for preparin, diluting and handling LG solutions safely and conveniently in 5 to 500 μl amounts was developed as well as a syringe for direct injection of μl-LG samples into capillary GC. Even technical grade LG are of high purity. GC/FID of LG solutions (starting at −60°C) allows the separation of volatile traces from the solvent peak: e.g., dichloromethane can be measured in the picogram range.

The initial state of liquid atomization by a fast gas stream is considered by viscous linear spatial stability analysis for parallel two-fluid flow. The unbounded basic velocity profile is characterized by different asymptotic velocities and a velocity deficit near the interface. We examine the influence of the velocity deficit on the spatial growth rates of two competing modes originating from the Kelvin-Helmholtz and viscosity contrast mechanisms. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)

Processes consist of different steps. If for example an aerobic conversion takes place in a solid particle the oxygen has to be transferred from the gas phase to the liquid phase and from the liquid phase to the solid phase. The rate of the overall process will be determined by the slowest process. Optimization of the process can be achieved by optimization of the slowest process step. In that case, however, an overview has to be made of all possible process steps. A useful tool for such an inventory is regime analysis. A system with immobilized biocatalysts has a complex behaviour. A complete description of the process for a wide range of conditions is time consuming or even impossible. This argument is valid for most biotechnological processes and a consistent approach to simplify these processes is regime analysis (Moser 1988, Roels 1983). In the regime analysis presented by Schouten et al. (1986), with immobilized Clostridium spp. for isopropanol/ butanol production, the effectiveness factor for the immobilized cells was estimated to be 1. They conclude that the isopropanol/butanol production is not diffusion controlled and the immobilized cells behave as free cells. New for the regime analysis presented here is the addition of a solid third phase with immobilized cells growing in a diffusion-controlled situation.

Storage tanks with pressurized liquid gases such as propane or chlorine represent a substantial hazardous potential. The dynamics of the release, for example through an accidentally generated opening, are studied. The most important quantities are the time required to empty the reservoir and the cooling of the fluid. The temperature of the liquid phase influences the vapour pressure which represents a driving force of the outflow dynamics. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A new method and apparatus are described for hydroperoxidation of organic compounds at the liquid/gas interface which is formed in a spirally curved tube. The energy required for stirring is removed, although extra energy is required for the compressors to enable the gas to provide the necessary agitation. The reaction rate should be higher than that in methods used at present.

Explosion hazard analysis of inflammable gas released spontaneously into the atmosphere. The processes of flash evaporation, atmospheric vapour cloud formation ignition and explosion after the bursting of vessels containing liquefied gas have been studied by model experiments with propylene heated up to 70°C and pressurized to 60 bar. The experiments have shown that a blast wave with considerable peak pressure in the vicinity of the vessel is produced already by flash expansion of the propylene. The experimentally determined decrease of peak pressure with growing distance could be scaled up to vessels of arbitrary size and different propylene temperatures. Scaling laws could be established as well for the calculation of peak pressure and positive pressure duration of the deflagration wave as functions of released mass and distance. The experiments have not revealed any evidence of a detonation process even when the cloud was ignited by an explosive charge.

An experimental program is described and experimental results presented for the response of an externally heated horizontal cylindrical tank protected by a PRV and partially filled with a pressure liquefied gas. Measurements of tank pressure, temperatures, mass discharge and void development, along with photography of internal fluid behavior are used to demonstrate the complex thermo-hydraulic behavior as a function of heating and valve position. The results are used to compare some of these parameters with analyses of stratification and void development.

When a small bubble is driven through a liquid phase to a liquid-gas interface, a thin liquid film forms between them and drains until an instability forms and coalescence occurs. Following Lin and Slattery (1982b), Chen et al. (1984) and Hahn et al. (1985) analyzed this process, neglecting the effects of electrostatic forces and of the surface viscosities. Here we extend their theory to include the effects of the surface viscosities. We employ a modification of the development by Barber and Hartland (1976; Flumerfelt et al., 1982) for a draining film bounded by parallel planes. For a large intermediate range of the surface viscosities, the coalescence time is a strong function of these parameters. Inclusion of the surface viscosities acts to moderate or even reverse trends previously established for the dependence of the coalescence time on the bubble radius, the viscosity of the film liquid, the interfacial tension, the strength of the London-van der Waals forces, and the density difference between the two phases.

Liquid propane and similar coolants are used in the rapid freezing of biological specimens. These coolants form explosive gas mixtures with air with a 14,000-fold increase in volume over that of the liquid. The liquefied gases have high vapour pressures and, unless they are maintained below their flashpoint, the vapour above them will reach ignitable concentrations. The flashpoint of liquid propane is -104°C. Ethane has a higher vapour pressure, and vapour mixed with air above liquid ethane can be ignited at a coolant temperature of -130°C. The danger is minimized if the coolant is maintained near its freezing point and under a nitrogen atmosphere, in a fume cupboard. Liquid nitrogen evaporates to a 690-fold increase in volume at room temperature. It is important to ventilate the working area, especially when cryo-sectioning in a small room, otherwise there is a possibility of asphyxiation.

Chlorine, a greenish yellow gas, was discovered in 1774 by Scheele, a Swedish chemist. One volume of liquid chlorine is equivalent to 455 volumes of chlorine gas. Chlorine was formerly produced by chemical means, but, during the last few years, it has been manufactured by the electrolytic decomposition of salt brine. Until recently, chlorine was known principally through its use in the form of chloride of lime (bleaching powder, hypochlorite of lime or hypo). This is produced by the action of chlorine gas upon slaked lime in lead-lined chambers. Coincident with the development of the electrolytic method of producing chlorine, there came the development of the machinery for liquefying the gas. As a result, chlorine is now shipped in steel drums of various capacities, including tank cars containing 15 tons. As shipped, it is in liquid form, under a pressure of about 80 pounds, the liquefied gas is dry and is between 99.5 and 100 per cent pure chlorine. The variation in the degree of purity is slight. As long as the gas is dry it will not corrode most metals.

The principle of the new gas-phase method of polycondensation consists of carrying out the polycondensation reaction of two high reactive compounds at a liquid—gas interface. The gas-phase method permits the synthesis of polyamides with rapidly hydrolyzing diacid chlorides (e.g., oxalyl chloride), which cannot be used for liquid—liquid polycondensation. The gas-phase synthesis of polyhexamethyleneoxamide from hexamethylenediamine and oxalyl chloride has been investigated in detail. The common features of gas-phase and interfacial methods of polycondensation are due to the fact that in both cases the chemical reaction proceeds in the polymeric film. The gas-phase methods can be used for the synthesis of a series of polymers.

Experimental data, believed accurate within ±0.5%, are presented for pressures of 100 to 8,000 Ib./sq. in. abs. for nine temperatures from 77° to 280°F. One isotherm, within 1° of the critical, indicates the detail required in further investigation of the critical region. These data were combined with the available literature values to prepare a table of recommended viscosity values with maximum uncertainty of ±2% for temperatures from 70° to 460°F. Two generalized correlations and the Enskog viscosity theory for dense gases exhibit significant errors in predicting the data. Methods are suggested for extrapolation of the values to higher temperatures and pressures.