Component Condensation Research Articles

Finite Time Blow Up in Kaniadakis–Quarati Model of Bose–Einstein Particles

We study a Fokker–Planck equation with linear diffusion and super-linear drift introduced by Kaniadakis and Quarati [12, 13] to describe the evolution of a gas of Bose–Einstein particles. For kinetic equation of this type it is well-known that, in the physical space ℝ3, the structure of the equilibrium Bose–Einstein distribution depends upon a parameter m*, the critical mass. We are able to describe the time-evolution of the solution in two different situations, which correspond to m ≪ m* and m ≫ m* respectively. In the former case, it is shown that the solution remains regular, while in the latter we prove that the solution starts to blow up at some finite time t c , for which we give an upper bound in terms of the initial mass. The results are in favor of the validation of the model, which, in the supercritical regime, could produce in finite time a transition from a normal fluid to one with a condensate component.

Droplet behaviour in a Ranque-Hilsch vortex tube

The vortex tube is an apparatus by which compressed gas is separated into cold and warm streams. Although the apparatus is mostly used for cooling, the possibility to use the vortex tube as a device for removing non-desired condensable components from gas mixtures is investigated. To give first insight on how droplets behave in the vortex tube, a MATLAB model is written. The model tracks Lagrangian droplets in time and space according to the forces acting on the droplets. Phase interactions, i.e. evaporation or condensation, are modeled according to the kinetic approach for phase interactions. Liquid (water) concentrations are shown for two cases where the humidity at the inlet of the vortex tube is varied from 0% to 50%. It is clearly observed from the results that the concentration of liquid increases with increasing humidity. The higher this concentration is, the higher the probability that droplets collide with each other and form larger droplets which are swirled towards the wall to form an easy-to-separate liquid film.

Thermodynamic evaluation of heat recovery through a Canopus heat exchanger for vapor compression refrigeration (VCR) system

Abstract This communication deals with the waste heat recovery from the industrial refrigeration and air-conditioning system by introducing Canopus heat exchanger. There is a considerable amount of low-grade heat available in large-capacity systems. To recover this low-grade heat, a Canopus heat exchanger is introduced between compressor and condenser components. The system feasibility is studied with various operating parameters and its effect on heat recovery factor and overall COP of the system. The parametric results obtained for different eco-friendly working fluids, such as R-134a and R-507a, have been presented. It is found that, in general, overall COP of the system is improved without affecting the actual performance of the system. The potential of low-grade heat availability is increased with increasing cooling capacity.

Efficient synthesis of mono- and disubstituted 2,3-dihydroquinazolin-4(1H)-ones using aluminum methanesulfonate as a reusable catalyst

A wide range of mono- and disubstituted 2,3-dihydroquinazolin-4(1H)-ones were synthesized via a one-pot three components condensation of isatoic anhydride, aldehydes, and ammonium salts or primary amines in the presence of aluminum methanesulfonate in EtOH/H2O solution. The catalyst is reusable and could be recycled for several runs without any distinct decrease in its efficiency. A plausible mechanism for this one-pot three components reaction was proposed.

An efficient, catalyst free synthesis of 3-(2′'-benzothiazolyl)-2,3-dihydroquinazolin-4(1H)-ones in aqueous medium

An efficient and environmentally benign protocol for the synthesis of 3-(2′-benzothiazolyl)-2,3-dihydroquinazolin-4(1H)-ones has been developed. The synthesis of these pharmacologically important compounds can be achieved by the three component condensation of isatoic/5-chloroisatoic anhydride, aldehyde, and 2-aminobenzothiazole in water: ethanol (1:1, v/v) without the aid of any catalyst.

A green synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature

Heterogeneous Tin (IV) hydrogen phosphate nanodisks [Sn(HPO4)2.H2O] efficiently catalyzed the one-pot three component condensation of aromatic aldehydes, β-ketoesters and urea to produce 3,4–dihydropyrimidin-2-ones under solvent-free conditions at room temperature. Also, the catalyst is equally applicable for the preparation of 1,5–benzodiazepines under the same reaction conditions. The optimum load of the catalyst required is 10 mole% and reusable. Hence, the process is green.

Fast and efficient solvent-free Passerini reaction

A Passerini three component condensation between a carboxylic acid, an aldehyde, and an isocyanide at high temperature under solvent-free conditions was developed. This methodology allows the formation of a broad range of α-acyloxyamides in excellent yields in short reaction times.

Synthesis of Hydrogen Polyoxides H2O4 and H2O3 and Their Characterization by Raman Spectroscopy

AbstractHydrogen tetroxide (H2O4) and hydrogen trioxide (H2O3) have been prepared in relatively large quantities as components of peroxy radical condensates. The polyoxides were characterized by the Raman spectra of the oxygen framework. Lines at 500, 756, and 878 cm–1 correspond to skeletal oscillations of H2O3 in the condensate (OOO bend, asymmetric OO stretch, symmetric OO stretch). Lines at 449, 589, 624, 827, and 865 cm–1 match the skeletal vibrations of H2O4 (OOO bend 1, OOO bend 2, center OO stretch, asymmetric OO stretch, symmetric OO stretch). The line of the O4 torsion vibration of hydrogen tetroxide was not observed experimentally. The assignment was confirmed by B3LYP/6‐31+G(d,p) calculations of the vibrational spectra. According to the information available in the literature, this work is the only report of the preparation of H2O4 in significant concentrations and its Raman spectrum. For the first time convincing evidence is provided for the existence of hydrogen tetroxide (in low‐temperature solids).

Variable-speed heat pump model for a wide range of cooling conditions and loads

A modular variable-speed heat pump model is developed from first principles. The system model consists of steady-state evaporator, compressor, and condenser component sub-models. The compressor model currently implemented accounts for re-expansion, valve pressure drop, and back leakage using empirical coefficients obtained from tests covering a wide range of pressure ratio and shaft speed. Variations in heat transfer coefficients with refrigerant and secondary fluid flow rates are modeled over a wide range of capacity. Pressure drops in piping and heat exchangers are also modeled. The resulting heat pump model is flexible and fast enough for use in finding optimal compressor, fan, and pump speeds and optimal subcooling for any specified capacity fraction and operating condition. To confirm the model's accuracy, simulation results are compared to experimental data with condenser inlet air temperatures ranging from 15°C to 45°C, evaporator inlet air (dry) from 14°C to 34°C, and cooling capacity from 1.1 kW to 3.9 kW. The refrigerant charge balance has not been modeled; instead, it is assumed that a liquid receiver maintains the necessary charge balance. Over this wide range of conditions, the coefficient of performance prediction errors are found to be ±10%. An example of configuring the HPM with a different evaporator demonstrates the benefits of a modular approach.

ChemInform Abstract: Ammonium Metavanadate as an Efficient Catalyst for the Synthesis of 2,4,5‐Triaryl‐1H‐imidazoles.

AbstractThe title compounds (III) and (V) are synthesized in an one‐pot three component condensation by using an inexpensive, mild, recoverable, and reusable catalyst.

Fe3O4 Nanoparticles as an Efficient and Magnetically Recoverable Catalyst for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones under Solvent-Free Conditions

The catalytic activity of Fe 3 O 4 nanoparticles (NPs) in a one-pot three component condensation reaction consisting of an aromatic aldehyde, urea or thiourea, and a β-dicarbonyl under solvent-free conditions was investigated. This reaction affords the corresponding dihydropyrimidinones (thiones) in high to excellent yields. Compared with the classical Biginelli reactions this method consistently gives a high yield, easy magnetic separation, a short reaction time, and catalyst reusability. The catalytic activity of Fe 3 O 4 nanoparticles (NPs) during the synthesis of dihydropyrimidinones under solvent-free conditions was investigated. The advantages of this method are a high yield, a short reaction time, easy magnetic separation, and catalyst reusability.

Quantum Kinetic Theory of Collisionless Superfluid Internal Convection

Superfluids can transport heat via simultaneous opposite flows of their spatially interpenetrating condensate and noncondensate components. While this internal convection is usually described within Landau's phenomenological two-fluid hydrodynamics, we apply quantum kinetic theory to a dilute Bose gas held between thermal reservoirs at different temperatures and show that the phenomenon also appears in collisionless kinetic regimes and should be directly observable in currently feasible experiments on trapped ultracold vapors.

ChemInform Abstract: Heterocyclization of N,N′‐Disubstituted p‐Phenylenediamines with Cyclic β‐Diketones and Formaldehyde. Synthesis of New Pyrido[2,3‐g]quinoline Derivatives.

AbstractDispiro derivatives of pyrido[2,3‐g]quinoline (IV) are selectively obtained in a three component condensation of diamines (I) with cyclic β‐diketones and formaldehyde under mild conditions.

A Three-Component Reaction between Azaarenes (Phenanthridine, Quinoline or Isoquinoline), Acetylenic Esters and Phenol Derivatives

Three component condensation reactions between azaarenes (phenanthridine, quinoline or isoquinoline) and acetylenic esters were undertaken in the presence of phenol derivatives (2,4-di-tert-butylphenol, 2,6-dimethylphenol, 4-methylphenol and 4-chloro-3,5-dimethylphenol) for generation of C-arylation in good yields. The reactions proceeded smoothly at room temperature without using any catalyst.

Three component condensation of 1H-pyrrol-2,3-dione with malononitrile and 4-hydroxycoumarin

Three component condensation of 1H-pyrrol-2,3-dione with malononitrile and 4-hydroxycoumarin

New three-component condensation reaction: synthesis of 1-[(alkylthio)(phenyl)methyl]-naphthalene-2-ol catalyzed by bromodimethylsulfonium bromide (BDMS)

Bromodimethylsulfonium bromide acts as an efficient catalyst for one pot three component condensation reactions of aldehydes, 2-naphthol, and thiols in acetonitrile at room temperature. Various aliphatic and aromatic thiols undergo conjugate addition with in situ generated enone in acetonitrile and provide good yields. The main features of this procedure are mild reaction conditions, good yields, and operational simplicity.

Measurement of Liquid–Liquid Equilibria for Condensate + Glycol and Condensate + Glycol + Water Systems

Today's oil and gas production requires the application of various chemicals in large amounts. To evaluate the effects of those chemicals on the environment, it is of crucial importance to know how much of the chemicals are discharged via produced water and how much is dissolved in the crude oil. The ultimate objective of this work is to develop a predictive thermodynamic model for the mutual solubility of oil, water, and polar chemicals. But for the development and validation of the model, experimental data are required. This work presents new experimental liquid–liquid equilibrium (LLE) data for 1,2-ethanediol (MEG) + condensate and MEG + water + condensate systems at temperatures from (275 to 323) K at atmospheric pressure. The condensate used in this work is a stabilized natural gas condensate from an offshore field in the North Sea. Compositional analysis of the natural gas condensate was carried out by gas chromatography, and detailed separation of individual condensate's components has been carried...

Polymeric Cracking of Waste Polyethylene Terephthalate to Chemicals and Energy

ABSTRACT Polyethylene terephthalate (PET) is a widely used thermo-plastic. PET residues represent on average 7.6 wt% of the different polymer wastes in Europe. Pyrolysis of these wastes is attracting increasing interest, and PET is a potential candidate for this thermal process. The paper measures and discusses the kinetics of the pyrolysis reaction in terms of the reaction rate constants as determined by dynamic thermogravimetric analysis, with special emphasis on the required heating rate to obtain relevant results. The product yields and compositions are also determined. Gaseous products represent 16–18 wt%. The amounts of condensables and carbonaceous residue are a function of the operating mode, with slow pyrolysis producing up to 24 wt% of carbonaceous residue. Major condensable components are benzoic acid, monovinyl terephthalate, divinyl terephthalate, vinyl benzoate, and benzene. The present paper complements previous literature findings by (1) the study of the influence of the heating rate on the reaction kinetics in dynamic pyrolysis tests, (2) the iso-thermal investigation in a fluidized bed reactor to pyrolyze PET, and (3) the assessment of upgrading and recovery of the products. The paper concludes with a proposed reactor recommendation for PET pyrolysis, in either the bubbling or circulating fluidized bed operating mode. IMPLICATIONS Plastic solid waste (PSW) represents up to 8% by wt and 20% by volume of household waste. Landfill disposal wastes valuable energy and chemical feedstock. Incineration for energetic valorization (waste-to-energy) is applied for ∼50% of PSW. To date, research focuses increasingly on pyrolysis, which has the advantage over incineration of producing value-added chemicals, even from commingled or mixed feedstock. The process gains in efficiency and yield if PSW fractions are collected separately or presegregated. The cost of separate collection is easily overcome by the value of the pyrolysis products. The pyrolysis of polyethylene terephthalate is developed as an example of the above.

1,4-Diazabicyclo[2.2.2]octane as an Efficient Catalyst for a Clean, One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives via Multicomponent Reaction in Aqueous Media

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as a mild and efficient catalyst for the synthesis of various tetrahydrobenzo[b]pyran derivatives via a one-pot, three component condensation of aromatic aldehydes, dimedone, and active methylene compounds. This method provides several advantages: a simple workup procedure, environmental friendliness, neutral conditions, and good yields. In addition, water or 50% aqueous ethanol was chosen as a green solvent.

Mechanisms for High Displacement Efficiency of Low-Temperature CO2 Floods

Summary CO2 floods at temperatures typically below 120°F can involve complex phase behavior, where a third CO2-rich liquid (L2) phase coexists with the oleic (L1) and gaseous (V) phases. Results of slimtube measurements in the literature show that an oil displacement by CO2 can achieve high displacement efficiency of more than 90% when three hydrocarbon phases coexist during the displacement. However, the mechanism for the high-displacement efficiency is uncertain because the complex interaction of phase behavior with flow during the displacement is not fully understood. In this paper, we present the first detailed study of three-phase behavior predictions and displacement efficiency for low-temperature CO2 floods. Four-component EOS models are initially used to investigate systematically the effects of pressure, temperature, and oil properties on development of three-phase regions and displacement efficiency. Multicomponent oil displacements by CO2 are then considered. We use a compositional reservoir simulator capable of robust three-phase equilibrium calculations. Results show that high displacement efficiency of low-temperature CO2 floods is a consequence of both condensing and vaporizing behavior. The L2 phase serves as a buffer between the immiscible V and L1 phases within the three-phase region. Components in the L1 phase first transfer efficiently to the L2 phase near a lower critical endpoint (LCEP). These oil components then transfer to the V phase near an upper critical endpoint (UCEP) at the trailing edge of the three-phase region. The CEPs are defined where two of the three coexisting phases merge in the presence of the other immiscible phase. Unlike two-phase displacements, condensation and vaporization of intermediate components occur simultaneously within the three-phase region. The simultaneous condensing/vaporizing behavior involving the CEPs is also confirmed for simulations of several west Texas oil displacements. Quaternary fluid models can predict qualitatively the complex displacements because four is the minimum number of components to develop CEP behavior in composition space at a fixed temperature and pressure.