Condensation Characteristics Research Articles

Characteristics of 2-chloropyridine and thiourea condensation. Structure of the as-formed products and their effect on coating properties during electrochemical nickel plating

The synthesis and spectral characterisation of 2-pyridylisothiuronium chloride were performed by regulating the rate of feeding 2-chloropyridine into a thiourea solution in ethyl alcohol for ensuring its low concentration in the reaction zone. According to the data of NMR spectroscopy (1H,13С,15N), the obtained compound represents an approximately equimolar mixture of two tautomers: the expected isothiuronium salt and pyridinium chloride with an isothiocarbamide substituting group in the 2nd position. The ability of isothiuronium salt to transit tautomerically to pyridinium salt is determined by the presence of two main centres, including nitrogen atoms of the isothiourea unit and a nitrogen atom of the pyridine ring. A quantum chemical analysis performed using the DFT method showed that the free energy values of the tautomers were similar, with the tautomer protonated on the nitrogen imido-atom being 2.9 (in the gas phase) and 4.7 kcal/mole (taking into account the dimethyl sulphoxide solvent DMSO at the PCM level) more advantageous as compared to the pyridinium salt. A small difference in the tautomer energies determines their formation in an approximately equimolar quantity. A rapid addition (5–10 mL/min) of 2-chloropyridine to the thiourea solution in the reaction zone creates the surplus of the reagent, acting as a base and causing splitting of the isotiuronium salt. This leads to an additional formation of bis(2-pyridyl)sulphide in the reaction medium, representing a valuable ligand for obtaining coordination compounds. The synthesised mixture of tautomers was examined as an additive to the standard nickel-plating electrolyte. In the concentration of 0.3–0.5 g/L, this additive ensured the production of bright low-porous nickel coatings at a sufficiently high current density of 5–10 A/dm2 and a current yield of 98–99 %.

Microfluidics for multiscale studies of biomolecular condensates.

Membraneless organelles formed through condensation of biomolecules in living cells have become the focus of sustained efforts to elucidate their mechanisms of formation and function. These condensates perform a range of vital functions in cells and are closely connected to key processes in functional and aberrant biology. Since these systems occupy a size scale intermediate between single proteins and conventional protein complexes on the one hand, and cellular length scales on the other hand, they have proved challenging to probe using conventional approaches from either protein science or cell biology. Additionally, condensate can form, solidify and perform functions on various time-scales. From a physical point of view, biomolecular condensates are colloidal soft matter systems, and microfluidic approaches, which originated in soft condensed matter research, have successfully been used to study biomolecular condensates. This review explores how microfluidics have aided condensate research into the thermodynamics, kinetics and other properties of condensates, by offering high-throughput and novel experimental setups.

Title Supersonic Condensation and Separation Characteristics of CO2-Rich Natural Gas under Different Pressures

Supersonic separation technology is a new natural gas sweetening method for the treatment of natural gas with high CO2 (carbon dioxide) content. The structures of the Laval nozzle and the supersonic separator were designed, and the mathematical models of supersonic condensation and swirling separation for CO2-CH4 mixture gas were established. The supersonic condensation characteristics of CO2 in natural gas and the separation characteristics of condensed droplets under different inlet pressures were studied. The results show that higher inlet pressure results in a larger droplet radius and higher liquid phase mass fraction; additionally, the influence of centrifugal force is more pronounced, and the separation efficiency and removal efficiency of CO2 are higher. When the inlet pressure is 6 and 9 MPa, the liquefaction efficiency at the Laval nozzle outlet increases from 56.90% to 79.97%, and the outlet droplet radius increases from 0.39 to 0.72 μm, and the removal efficiency is 31.25% and 54.52%, respectively. The effects of inlet pressures on the removal efficiency of the supersonic separator are complicated and are controlled by the combined effects of liquefaction capacity of the nozzle and centrifugal separation capacity of the swirl vane.

Fault indicator based on stator current under early stage SISC in synchronous condensers

In this study, the stator current characteristics of synchronous condensers for stator interturn short-circuit (SISC) fault in the early stage are investigated using theoretical derivation, finite-element analysis (FEA) and experimental research. In contrast to previous studies, this study considers the real operation characteristics of synchronous condensers that need to change the exciting current to meet the reactive power demand of the power grid. Thus, a new SISC fault indicator (FI) based on the stator current is proposed in this study. The new FI can identify incipient SISC and suppress the interference of the exciting current variation. A customized synchronous machine and TTS-300-2 synchronous condenser are simulated using FEA to demonstrate the effectiveness of the FI. Furthermore, experimental tests are conducted in a customized synchronous machine to prove the practical significance of the studies.

Numerical simulation study on the structure optimization of liquid separation device in supersonic separator

ABSTRACT The effect of the supersonic separator on the condensation characteristics and fluid separation efficiency is not clear, and the structure of the liquid separation device still has room for optimization. Therefore, based on the rear-swirl type supersonic separator, three kinds of drainage ports and three kinds of liquid collection tank structures were proposed. The supersonic flow and separation process was studied numerically under nine different combination structures. The influence of the drainage port’s length and width and the inclination of the liquid collection tank on the liquefaction and separation process were analyzed. The separation trajectory of condensation droplets and the influence of particle size on the separation efficiency were clarified. The results show that the liquid separation device structure of the Em-Attached wall type can take condensation and separation efficiency into account, and its separation effect is the best. The optimal size of the key components was obtained: the length of the drainage port is 150 mm, the width of the drainage port is 3 mm, and the inclination of the liquid collection tank is 14 °. The particle size of the condensation droplets is in the range of 2 μm to 6 μm.

Research on condensation characteristics of supercritical carbon dioxide in Laval nozzle considering working condition of power cycles

The supercritical carbon dioxide (sCO2) thermal power cycle is a solution for generation IV nuclear energy systems. The potential condensation in the key equipment of the power system poses a serious threat to the safe operation of the system. Aiming at the condensation that may occur inside the sCO2 compressor, this paper numerically simulates the condensation that occurs in a convergent-divergent nozzle. The wet steam model and the homogeneous equilibrium model (HEM) are present and compared with the experimental data. The HEM is used to calculate the influence of the inlet conditions of the fluid into the nozzle and the different expansion rates corresponding to different nozzle shapes on the condensation phenomenon. The results show that the HEM can represent the two-phase flow of carbon dioxide in the nozzle. The nozzle inlet boundary conditions and nozzle expansion rate have an important influence on the condensation characteristics, the former influences the condensation position, while the expansion rate has an influence on the outlet humidity and pressure drop.

A novel strategy to improve steam heat utilization and reduce carbon emissions during heavy oil development

In recent years, the green transformation of the traditional energy industry and the reduction of carbon emissions have attracted widespread societal attention. In the thermal recovery process of heavy oil, the low heat utilization rate has always been the bottleneck restricting its production. In addition, the associated flue gas emissions also pose a considerable challenge to environmental protection. In this paper, flue gas and SiO2 aerogel were jointly applied to reduce steam heat loss while achieving exhaust gas sequestration. Condensation heat transfer experiments were carried out to explore the mechanism of the two affecting the heat dissipation process of steam liquefaction. A series of displacement experiments with different injection methods in a one-dimensional sandpack were performed to select combinations of developing heavy oil with high efficiency and low carbon. By detecting the temperature changes of the model and calculating the final storage volume, the effects of promoting steam chamber expansion and flue gas sequestration were evaluated. The results showed that the aerogel adsorption layer could change the wettability of the condensing surface, thereby showing the characteristics of film condensation. Flue gas molecules could be captured by aerogel nanofluids, further exerting a synergistic thermal insulation effect, and the temperature of the deep reservoir increased by 7.7 °C. Simultaneously, the crude oil recovery increased by 8.8% compared with pure steam flooding. Moreover, the numerous nanoparticle-stabilized foams generated via this method were noted as an essential way to sequester carbon in a high water-cut formation, and the final sequestration rate reached 77.4%.

Experimental research on the volatilization and condensation of ammonium bisulfate as SCR byproduct

Abstract In this paper, the research progress of ammonium bisulfate (ABS) volatilization in coal-fired power plants the SCR denitrification process was reviewed. Combination with self-made experiments, SEM, flue gas analyzer and TG-DTG curves of ABS and ion chromatography. The volatilization and condensation characteristics of ABS were investigated carefully. Results show that as the temperature increased by 50 oC, the ABS/AS volatilization rate increased by an order of magnitude. The decomposition process of ABS should have a two-step reaction. The reaction in the initial volatiliza-tion stage is ABS dehydration turned into (NH4)2S2O7. The reaction in the rapid volat-ilization stage is (NH4)2S2O7 decomposed into NH3, N2, SO2 and H2O. There is an inter-section in the reaction temperature range (especially 300 oC) between the two-step re-action. This research provides an experimental basis for temperature control of ABS to avoid air pre-heater fouling.

Effect of non-condensable gas on submerged steam jet condensation in a narrow pipe

A visualization study was performed to investigate the effect of non-condensable gas on stable submerged steam jet condensation in water flow in a narrow pipe. The direct contact condensation (DCC) characteristics including jet plume shapes, dimensionless penetration length and average heat transfer coefficient were analyzed in a wide range of water flow subcooling, Reynolds number of water flow and steam–air mixture flow rates. As four different steam plume shapes for pure steam jet in subcooled water flow in a pipe were reported in the previous research, the effect of non-condensable gas on the four steam plume shapes was investigated by introducing a certain amount of air into steam. In the current study, the submerged steam–air mixture jet behavior was investigated through direct visualization techniques. The effect of non-condensable gas on jet plume shapes was recorded by using a high speed camera. The gas–liquid interface and the dimensionless penetration length was obtained by digital image processing method implemented by a MATLAB subroutine. Then the average heat transfer coefficient was calculated based on thermal equilibrium of gas–liquid interface. In the experiment, the gas mass flux at nozzle exit was within 320–780 kg/m2/s, with no more than 1 % non-condensable gas. The results indicated that the non-condensable gas plays an important role on the gas–liquid interface, jet penetration length and heat transfer coefficient. It was found that when 1 % non-condensable gas was mixed with steam jet, the dimensionless penetration length was extended by 16–70 %, and the average heat transfer coefficient decreased by 12–50 %. Based on the force-balance of jet plume, a new quantitative correlation for the steam–air mixture jet penetration length was proposed. The predicted jet penetration length agrees well with the experimental measured values.

Experimental study of condensation characteristics and operation strategies of induction radiant air-conditioning system

To study the operation and condensation characteristics of an induction radiant air-conditioning system as a novel system that combines induction ventilation and radiant air conditioning, the characteristics of convection and condensation of an indoor terminal device radiant induction unit were studied. The mass transfer coefficient, condensation temperature, and condensation rate were analyzed experimentally. The time required to achieve a steady state indoor thermal environment was collected. The results indicated that the primary airflow rate and temperature mainly affected the mass transfer coefficient, condensation temperature, and condensation rate. When the indoor thermal environment reached a steady state, the heat transfer performance of the radiant induction unit was mainly affected by the primary air temperature. When condensation occurred, the primary airflow rate had a greater influence on the condensation rate. The start-up and response performances of the system were better than those of a traditional radiant air-conditioning system. In the condensation condition, reasonable control strategies maintain the primary air temperature and adjust the primary air flow rate, which can ensure sufficient heat transfer and stabilize the indoor thermal environment faster.

Modeling and simulation of synchronous condenser based on digital twin

With the continuous development of UHV DC transmission technology, the synchronous condenser has become an important supporting equipment in the DC transmission project, and its mechanism modeling and simulation have important practical significance. Based on the digital twin technology, this paper establishes a hybrid symbolic numerical model of synchronous condenser, which can realize model reuse and rapid deployment. First, it analyzes the basic characteristics of the synchronous condenser, and then proposes the digital twin model framework of this article. The digital twin model of the synchronous condenser is developed based on the Andes power system simulation tool. Finally, a simulation case is used to verify the digital twin model of the synchronous condenser. The experimental results show that the digital twin model can realize simulation operation and fault characteristic response simulation.

Influence of shock wave/boundary layer interaction on condensation flow and energy recovery in supersonic nozzle

Shock train phenomenon occurs when the Mach number increases during the process of energy recovery in the nozzle. However, the reduction of wet natural gas purification efficiency and the increase in energy loss can be caused by shock wave in the supersonic separator. This study focused on the condensation characteristics and pressure energy recovery efficiency under the shock train in the Laval nozzle. A mathematical model was developed for the process of methane-water vapour supersonic condensation and verified by condensation experiments. The results demonstrate that the length of the boundary layer separation interval can be reduced by 0.142 m with a decrease of 0.909 upstream Mach number from 2.367 to 1.458. Multiple nucleation of vapour occurs under the effect of shock train. The droplet growth interval increases from 0 to 0.0859 m and the liquid mass fraction enhances from 0 to 0.12% as the pressure energy recovery efficiency decreasing from 80% to 30%. This indicates that the suitable pressure energy recovery efficiency from 40% to 60% can effectively control the location of the shock train and organize its structure in the nozzle to reduce the separation length of boundary layer and improve the nozzle liquefaction efficiency.

Development of Geothermal Equipment for and Construction of the Verkhne-Mutnovsk and Mutnovsk Geothermal Power Plants

Modern geothermal power generation systems have reached considerable commercial maturity and are successfully competing with other energy generation methods. Geothermal energy has a number of advantages: low cost of electricity, independence from climatic conditions, and high environmental friendliness. The geothermal power plant (GeoPP) capacity factor is well above the levels of this indicator for energy technologies that use other renewable energy sources. In Russia, there are prerequisites for effective use of geothermal energy for supplying power to remote and isolated regions that have huge reserves of geothermal resources. The article summarizes and analyzes the experience gained from development of domestic geothermal equipment and construction of modern geothermal power plants: the Verkhne-Mutnovsk GeoPP and Mutnovsk GeoPP. The geothermal fluid features influencing the design and process solutions applied in developing a GeoPP are considered. The principles of designing the block-modular Verkhne-Mutnovsk GeoPP are described, and the advantages and high efficiency of the steam treatment plant for ensuring reliable operation of the Verkhne-Mutnovsk GeoPP and Mutnovsk GeoPP turbine units are noted. The design features of the turbine flow paths at the Mutnovsk GeoPP with a capacity of 25 MW and Verkhne-Mutnovsk GeoPP with a capacity of 4 MW are given. The characteristics of unique air-cooled condensers for the Verkhne-Mutnovsk GeoPP and direct-contact condensers for the Mutnovsk GeoPP are presented. The further development lines of the Verkhne-Mutnovsk and Mutnovsk GeoPPs have been determined.

Experimental investigation on condensation characteristics of a novel radiant terminal based on sepiolite composite humidity-conditioning coating

The problem of condensation hinders the application and popularization of the radiant cooling system. According to the characteristics of temperature and humidity independent control of the radiant cooling system, a novel humidity-conditioning radiant terminal combined with solid humidity-conditioning material is proposed which can control temperature and humidity simultaneously, and a sepiolite composite humidity-conditioning coating (SCHCC) suitable for the radiant terminal with good humidity control ability in high relative humidity environment is prepared. The humidity-conditioning coating can adsorb water vapor in the air to reduce the risk of condensation that is different from the surface condensation of traditional radiant terminals. Then, the condensation and desorption characteristics of three humidity-conditioning boards are tested which is considered scaled-down humidity-conditioning radiant terminal. The results show that SCHCC has good humidity control ability in a high relative humidity environment, the moisture adsorption capacity of SCHCC between 85% RH and 95% RH is 0.208 g/g, which is 11.43 and 22.47 times that of gypsum and diatomite. The sepiolite based humidity-conditioning board (SHCB) with the best moisture adsorption characteristics has the longest condensation time, and the condensation time increases with the decrease of undercooling. SHCB also shows better humidity control ability even for the experimental condition without condensation within 300 min. In summary, SHCB can reduce the moisture content of indoor air through its excellent hygroscopic properties, and reduce the risk of condensation at the radiant terminal. • A novel humidity-conditioning radiant terminal is proposed. • The material has good humidity control ability under high relative humidity. • The condensation and desorption behavior of the novel radiant terminal is tested. • The novel radiant terminal can effectively prolong the surface condensation time.

Carbon capture in laval nozzles with different bicubic parametric curves and translation of witoszynski curves

This work investigates the influence of convergent curve of supersonic nozzle on the carbon separation process. The CFD model based on nucleation and growth theory, second-order upwind scheme and density-based solution method are employed to predict the CO2 supersonic separation process in the nozzle. The effects of bicubic parametric curve and translation of Witoszynski curve on flow characteristics and spontaneous condensation characteristics are illustrated. The results show that the mixed gas accelerates and deviates from the equilibrium state in the Laval nozzle, and nucleation occurs when the supersaturation is greater than 1.81. After nucleation, gas enters the droplet growth stage, during which mass and heat transfer are carried out between gas and liquid phase, and the droplet radius increases continuously. With the increase of the parameter xm in the bicubic parametric curve equation and the axis shift quantity yh in the translation of Witoszynski curve equation, the flow parameters in the nozzle change more violently, the nucleation location moves to the nozzle exit, and the interphase mass transfer rate and liquid fraction decrease in varying degrees.

Asymmetric Condensation Characteristics during Dropwise Condensation in the Presence of Non-condensable Gas: A Lattice Boltzmann Study.

In this work, the condensation characteristics of droplets considering the non-condensable gas with different interaction effects are numerically studied utilizing a multicomponent multiphase thermal lattice Boltzmann (LB) model, with a special focus on the asymmetric nature induced by the interaction effect. The results demonstrate that for isolated-like growth with negligible interactions, the condensation characteristics, that is, the concentration profile, the temperature distribution, and the flow pattern, are typically symmetric in nature. For the growth regime in a pattern, the droplet has to compete with its neighbors for catching vapor, which leads to an overlapping concentration profile (namely the interaction effect). The distribution of the condensation flux on the droplet surface is consequently modified, which contributes to the asymmetric flow pattern and temperature profile. The condensation characteristics for droplet growth in a pattern present an asymmetric nature. Significantly, the asymmetric condensation flux resulting from the interaction effect can induce droplet motion. The results further demonstrate that the interaction strongly depends on the droplet's spatial and size distribution, including two crucial parameters, namely the inter-distance and relative size of droplets. The asymmetric condensation characteristics are consequently dependent on the difference in the interaction intensities on both sides of the droplet. Finally, we demonstrate numerically and theoretically that the evolution of the droplet radius versus time can be suitably described by a power law; the corresponding exponent is kept at a constant of 0.50 for isolated-like growth and is strongly sensitive to the interaction effect for the growth in a pattern.

Effects of gradient and patterned wetting configuration on condensation over hybrid wetting surface from atomistic viewpoint

In this study, atomistic simulations have been conducted in order to illustrate the effects of gradient and patterned wetting configurations on nanoscale condensation over hybrid wetting surfaces. To pursue this objective, a three-phase argon-platinum atomistic system has been modeled, consisting of two solid surfaces and two different phases of argon atoms. Following the necessary equilibration of the atomistic system at 90 K, the temperatures of the upper and lower surfaces are maintained at 130 K and 90 K, respectively, to make them serve as evaporating and condensing surfaces. The wetting characteristic of the lower surface is kept unchanged in all of the cases to corroborate the uniform evaporating condition, while that of the condensing wall has been changed to follow two major classes, namely, gradient and patterned wetting profiles. Functionally gradient wetting (FGW) surfaces have been modeled utilizing the power-law function from the notion of functionally graded material (FGM), whereas patterned wetting surfaces are modeled by juxtaposing the regions of different wettability. The condensation characteristics of different surfaces are reported with important parameters such as nucleation rate, cluster growth and coalescence, thermal resistance at the solid–liquid interface, condensed fluid atoms, mass flux of the condensate, condensing wall heat flux, and surface tension profile. The simulation results have revealed that an increased proportion of hydrophilic atoms enhances the condensation heat transfer. In addition, FGW surfaces have been found to be better than patterned ones in terms of condensation heat transfer enhancement.

Experimental study on condensation heat transfer characteristics of steam in rectangular channels rotating about a parallel axis

• Nu in rotating channel increases with Re but decreases with steam temperature. • Pressure drop in rotating channel increases with Re and steam temperature. • Propose a new heat transfer correlation for steam condensation in rotating channel. In the papermaking industry, a kind of new cylinder dryer with multiple small and rectangular channels are employed to enhance the drying efficiency of drying machine. In practical working conditions, the multi-channel cylinder dryer runs under rotating states that could affect the heat transfer characteristics of the inside two-phase flow. However, the fluid heat transfer characteristics in the multi-channel at rotating states have not been well explored. In this study, a set of rotating experimental system is established to investigate the condensation characteristics and pressure drop changes of steam in rotating rectangular channels. Firstly, the experimental apparatus and the data processing method are described in detail. Then the effects of rotation speed, mass flux and steam temperature on the heat transfer coefficients and pressure drop are studied through experiment. The results show that when Re is small, the heat transfer coefficient first increases and then decreases with the increased Re ω ; when Re is large, the heat transfer coefficient increases with the increased Re ω . Moreover, the heat transfer coefficient decreases as the steam temperature increases. In addition, the pressure drop decreases with the increased Re ω while increases with the increased Re and steam temperature. Finally, a heat transfer model of two-phase flow condensation under rotating states is developed to predict the heat transfer coefficient of steam in rotating multiple channels.

Capillary condensation and evaporation of n-butane and iso-butane in nanoporous media: Experimental study of the effects of pore size and temperature using an automated gravimetric apparatus

Understanding the confinement-induced phase behavior of fluids stored in nanometer-sized pores of solid materials is paramount in various science and engineering applications. Experimental findings describing fluid phase behavior in confinement are often used to develop the efficient and accurate equation of state models that can then provide a cost-effective approach to predict such information for different applications. However, there is a scarcity of experimental data in the literature that can offer insights into the confinement effects under varying conditions. The present work endeavors to provide new experimental data on the effects of pore size and temperature on the confined phase behavior of two chemical species (n-Butane and iso-Butane) and thereby improve the current understanding of the impact of these parameters on capillary condensation, evaporation, and hysteresis. We use a patented gravimetric apparatus that was upgraded in this study by the development and incorporation of advanced automated data acquisition modules. The automation module improved the data collection quality by fine-tuning the fluid injection and withdrawal processes which significantly enhanced the accuracy and precision of the measured isotherms. The capillary condensation and evaporation processes were then studied using a nanoporous material known as Mobil Composition of Matter No. 41 (MCM-41), a mesoporous medium with well-defined pore shape and sizes. The isotherms were obtained for a wide range of temperatures (−7, −3, 0, 7, 8.7, 17, and 27 °C) and using MCM-41 with various pore sizes (60, 80, 100, and 120 Å). The accuracy of the measurements was validated against the phase behavior data of bulk n-Butane and iso-Butane reported by the National Institute of Standards and Technology (NIST). The capillary condensation pressures obtained from the isotherms for different pore sizes agreed with the trends reported in the literature. The results show that the capillary condensation pressures of the fluids increase with the pore size and temperature. The measured isotherms and capillary condensation pressures provide new data sets on the condensation characteristics of n-Butane and iso-Butane. They are expected to contribute to the fundamental understanding of the confined phase behavior of hydrocarbons and thereby advance the development of improved equations of state models that can accurately describe the phase behavior of fluids in nanoporous media. PC-SAFT/Laplace EOS was used to model the phase behavior of the fluids under confinement. The predictions from the PC-SAFT model agree with previous data therefore the results from this study can be integrated into building more robust models.

Numerical study on the condensation characteristics of natural gas in the throttle valve

Due to the cooling effect of natural gas throttling, spontaneous condensation will occur in the throttle valve, which may affect pipeline system efficiency. However, the condensation characteristics (such as nucleation rate and condensation rate) remain unclear, and the traditional method based on the isenthalpic hypothesis can hardly solve this non-equilibrium issue. Based on the geometry differences between the throttle valve and the Laval nozzle, this paper explored the condensation parameters of the CH4–C2H6 binary mixture in the throttle valve and the Laval nozzle using CFD techniques (solving non-equilibrium condensation at a lower cost). This paper discussed the influence of the inlet pressure and inlet temperature on the spontaneous condensation process in the throttle valve as well. The findings are that the nucleation and droplet growth regions in the throttle valve are closer to the throat but narrower than that of the Laval nozzle, and the liquid mass fraction decreases after reaching the peak value. The onset of droplet nucleation and droplet growth is closer to the throat when increases inlet pressure or decreases inlet temperature. The condensation rate of ethane in the throttle valve is lower than that in the Laval nozzle, and the sensitivity of the nucleation rate and the Wilson point to the inlet parameters is higher and lower than that in the Laval nozzle, respectively.. The main innovation of the paper lies in revealing the differences in the condensation between the throttle valve and the Laval nozzle using the non-equilibrium method.