High-temperature Liquid Water Research Articles

Investigation of the Effect of Hot Fluid on Deformation in T-Shaped Pipes by FSI Method Using Different Material

In this study, the high-temperature liquid water flow through the cross-section of a T pipe and the effect of the temperature of the liquid on the pipe material has been investigated. Pipe deformation caused by fluid temperature has been analyzed by the Fluid-structure interaction method. The effect of temperature distribution inside the pipe has been considered as thermal load in the structural analysis of the pipe body. The finite volume method has been used in the study with numerical methods. While k-ε is preferred as the turbulence model, the mesh file created to be used in the analysis contains 200,000 grid cells. For all calculations, the Reynolds number has been set to 3900 and kept constant. The geometry of the T pipe, the fluid passing through the pipe and used the boundary have been constant for the numerical analysis made in the study. The pipe material has been determined as the only parameter that changed. As different pipe materials magnesium, aluminum, copper, steel, concrete, cast iron, and titanium have been used. As a result of the study, thermal strain, total deformation, and directional deformation values have been determined. As a result, it has been determined that the greatest deformation under thermal load is in magnesium pipes, and the smallest deformation is in titanium pipes. It has been observed that the total amount of deformation of the pipe made of magnesium is three times higher than that of the titanium pipe.

Experimental and numerical study of heat and mass transfer between high temperature supersonic gas flow and liquid water in a cylindrical duct

The mixing process of a high temperature combustion gas and liquid water conveying large amounts of heat and mass transfer in a very short period of time is investigated experimentally and numerically. A solid propellant produces hot gas into a cylindrical duct where water is supplied through water injectors, facilitating instantaneous mixing accompanied by evaporation and condensation along the duct. Gas generator fire tests are carried out to confirm performance. A cylindrical duct is subsequently connected to the rear end of the gas generator with the liquid water supply system, and experiments are performed for three different amounts of water being injected into the supersonic hot gas. A numerical scheme for a homogenous mixture model with Lee's mass transfer model is applied, and comparisons are made with the experiments. Next, both the experimental and numerical results are fairly compared. The empirical coefficients of evaporation rate for the Hertz-Knudsen-Scharage (HKS) and wall film model (WFM) equations are proposed.

Preparing lignin-rich microcrystalline cellulose from spruce chemithermomechanical pulp fiber by Fe3+ enhanced high temperature liquid water treatment

Preparing lignin-rich microcrystalline cellulose from spruce chemithermomechanical pulp fiber by Fe3+ enhanced high temperature liquid water treatment

Novel Green Method for the Synthesis of Monoacetin over Bifunctional Cu-Cr Phosphates under the CO2 Atmosphere.

Monoacetin was synthesized using a novel green method in which acetonitrile was hydrolyzed and then esterified with glycerol over Cu-Cr phosphates under the CO2 atmosphere. Monoacetin was synthesized with high yield (87.6% glycerol conversion and 86.3% monoacetin selectivity) through this one-pot cascade method. In this process, acetonitrile can react with water to form acetamide and further undergo esterification with glycerol. There are two main reasons for obtaining monoacetin in high yield: (1) the interaction of CO2 with high-temperature liquid water enhances the acid strength of the reaction system and then promotes the activation of acetonitrile; and (2) the introduction of Cr species causes a synergistic effect between Cu and Cr species to adjust the acidity and basicity of the catalyst. The introduction of Cr species converts eight-coordinated Cu2+ into four-coordinated Cu2+ to improve the acidity of the catalyst. The introduction of Cr species also causes the surface oxygen to be transformed into lattice oxygen to enhance the basicity of the catalyst. These bimetallic phosphate materials may provide a new pathway for the application of acid-base bifunctional catalytic reactions.

Kinetics Study of Acid Catalyzed Degradation of Glucose in High-Temperature Liquid Water

Glucose is the most abundant monosaccharide in nature, glucose obtained from cellulose and starch, it is many used to degradation process, and for the production of several organic compounds, one of the degradation products of glucose is an HMF (5-hydroxymethylfurfural). HMF is a platform chemical, which can be converted into several chemical and liquid fuels through hydrogenation, oxidation, and esterification. The objective of this researches has studied the kinetics of glucose degradation using acid-catalyzed (H2SO4) in high-temperature liquid water and observe the effect of acid concentration and temperature on degradation of glucose to HMF. In this research was used reactor with pressure 10 atm, with variation time of reaction, sulfuric acid concentration, and temperature of the reaction. From this research found kinetics of glucose degradation was followed by the first-order reaction in each variable. Activation Energy (Ea) values were 7306,593 J/mol; 6341,59 J/mol; 3988,14 J/mol and 3988,14 J/mol on the concentration sulfuric acid 0,05M; 0,1 M; 0,05M, from that result indicated that reaction rate was increase when activation energy was decrease this was related to Arrhenius equation. The effect of acid concentration on degradation glucose was the higher acid concentration used, the more glucose was degraded, and more HMF was formed. Meanwhile, the effect of temperature of reaction on degradation glucose was the higher temperature of the reaction, more glucose was degraded, and more HMF was formed. The highest value of HMF was in operation condition of concentration H2SO4 0,5 M at 175°C, with a time of reaction 120 minutes. However, the reduction rate of glucose was not equal to the rate of formation of HMF (5-hydroxymethylfurfural), it can be indicated that HMF (5-hydroxymethylfurfural) was not the only product of degradation of glucose, but the others product might be formed from this operating condition. The other product that might be formed was humin and levulinic acid.

A novel method for preparing microcrystalline cellulose from bleached chemical pulp using transition metal ions enhanced high temperature liquid water process

A novel method for preparing microcrystalline cellulose (MCC) from bleached chemical pulp based on the transition metal ion-enhanced high temperature liquid water (HTLW) process was established in this study. Transition metal ions (Fe3+, Cu2+ or Cr3+) were used to enhance the depolymerization effect of HTLW treatment on fibers. Hemicelluloses are selectively removed, resulting in an increase in the α-cellulose content; cellulose undergoes hydrolytic degradation, causing a significant decrease in the average degree of polymerization (DP). SEM images indicated that the as-prepared MCC had granular or rod-like shape. The repose angle results showed a desirable fluidity of obtained MCC. The copper number results showed an increase in the reducing end groups of the obtained MCC. The XRD analysis indicated that the cellulose crystallite exhibited negligible changes, and the crystallization index (CI) increased. However, a very high concentration of transition metal ions lowered the CI. The transition metal ion-enhanced HTLW treatment provides an acid free method for preparing MCC.

A novel acid catalyst based on super/subcritical CO 2 -enriched water for the efficient esterification of rosin

Rosin esters are widely applied as masticatory substances and beverage stabilizers, while classical acid-catalysed processes will lead to metal residue or environmental issues. Super/subcritical CO2–enriched high temperature liquid water (HTLW) as a green acid catalyst in the esterification reaction of rosin with glycerol was investigated. The pH of CO2–H2O binary system, as calculated based on gas–liquid equilibrium, charge balance and chemical equilibrium equations, ranged from 3.49 to 3.70 depending on the reaction conditions, indicating effective acid catalysis. Response surface methodology experiments showed the optimum conditions were 3.5 h, 3.9 MPa CO2 pressure, a rosin-to-glycerol molar ratio of 1.32 and 269°C, and an enhanced esterification yield of 94.74% was achieved, which was superior to that obtained using a ZnO catalyst. It was found that the esterification kinetics was a pseudo first-order reaction, and the enthalpy and entropy of activation were calculated using the Arrhenius–Polanyi equation. The presence of super/subcritical CO2-enriched HTLW catalyst can decrease the activation energy and significantly accelerate the reaction rate.

Thermally and Chemically Stable Candle Soot Superhydrophobic Surface with Excellent Self-Cleaning Properties in Air and Oil

In this report, a people-considered waste-candle soot generated from incomplete combustion of the middle zone of candle was used to coat the glass slide for fabricating the superhydrophobic surface. The candle soot coating surface followed by deposition of methyltrichlorosilane (MTCS) was characterized through field emission scanning electron microscope, contact angle measurement in air and oil, self-cleaning test, high temperature, and corrosive liquid resistance test and water drop impact experiment, respectively. Interestingly, the candle soot layer after deposition of MTCS presented a coral-like structure and exhibited high water contact angle of 161° and a low sliding angle of 3° in air, which demonstrated that it had excellent superhydrophobicity in air. Of course, the coating also exhibited high water contact angle and low sliding angle in oil. Apart from that, results of high temperature and corrosive liquid resistance tests implied that the superhydrophobic coating can keep stability after treatm...

Benzyl methyl ether production from benzyl alcohol and methanol in carbonic water

Synthesis of benzyl methyl ether from benzyl alcohol and methanol in high-temperature carbonic water was studied in a batch reactor. Benzyl methyl ether formation was not observed by reacting benzyl alcohol with only methanol under supercritical conditions at 573K. On the other hand, benzyl methyl ether was formed by the treatment of benzyl alcohol in an aqueous methanol solution at 573K. 12% of benzyl methyl ether yield was obtained in aqueous methanol solution (methanol to water molar ratio of 0.025mol/0.11mol) at 573K in 60min and the yield enhanced to 33% by the addition of 18MPa of carbon dioxide to the aqueous solution. As the etherification is an acid catalyzed reaction, the protons derived from the dissociation of water molecules could be responsible for the etherification of benzyl alcohol in an aqueous methanol solution at 573K. The enhancement of benzyl methyl ether yield by the addition of carbon dioxide in aqueous methanol solution is caused by the increase of the number of protons derived from carbonic acid, which is formed in high-temperature liquid water under high-pressured carbon dioxide.

Purification of cellulose from bleached pulp by Lewis Base-enhanced high-temperature liquid water treatment

Applications of cellulose-based materials that require high-purity cellulose as a feedstock are becoming increasingly common. However, reported methods for hemicellulose removal are comparatively complicated. In this study, a Lewis base-enhanced high-temperature liquid water (HTLW) treatment was used to purify cellulose. The variation of carbohydrate content, average degree of polymerization (DP), and the crystalline index of specimens of the purified cellulose were investigated. After primary HTLW treatment, the alpha-cellulose content of specimens increased distinctly; also, the alkali solubility decreased. The DP of the specimens decreased dramatically after HLTW treatment. The incorporation of a Lewis base was beneficial for maintaining DP and for removing hemicellulose selectively. Simultaneously, the results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that the chemical and crystal structure of the specimens were unchanged. Based on the experimental results, Lewis base-enhanced HTLW is a promising method to prepare high-purity cellulose.

Study on the Effect of water Injection Momentum on the Cooling Effect of Rocket Engine Exhaust Plume

For the study of water injection momentum factors impact on flow field of the rocket engine tail flame, the numerical computation model of gas-liquid two phase flow in the coupling of high temperature and high speed gas flow and low temperature liquid water is established. The accuracy and reliability of the numerical model are verified by experiments. Based on the numerical model, the relationship between the flow rate and the cooling effect is analyzed by changing the water injection momentum of the water spray pipes. And the effective mathematical expression is obtained. What’s more, by changing the number of the water spray and using small flow water injection, the cooling effect is analyzed to check the application range of the mathematical expressions. The results show that: the impact and erosion of the gas flow field could be reduced greatly by water injection, and there are two parts in the gas flow field, which are the slow cooling area and the fast cooling area. In the fast cooling area, the influence of the water flow momentum and nozzle quantity on the cooling effect can be expressed by mathematical functions without causing bifurcation flow for the mainstream gas. The conclusion provides a theoretical reference for the engineering application.

Copper-Catalyzed Decarboxylation of 2,4,5-Trifluorobenzoic Acid in NH3-Enriched High-Temperature Liquid Water

1,2,4-Trifluorobenzene, the decarboxylation product of 2,4,5-trifluorobenzoic acid, is an important raw material for synthesizing sitagliptin phosphate, the main medicinal treatment for diabetes. The traditional synthesis suffers from environmental concerns; therefore, in this work, a series of metal catalysts was employed to catalyze the decarboxylation of 2,4,5-trifluorbenzoic acid in NH3-enriched high-temperature liquid water (HTLW) to address these concerns. Copper catalysts exhibited excellent performance, and heterogeneous copper catalysts, such as Cu and Cu2O, led to a higher yield of 1,2,4-trifluorobenzene (89.1%) than homogeneous copper catalysts, such as CuCl2 and CuCl. The effects of catalyst loading and reactant loading on the decarboxylation of 2,4,5-trifluorbenzoic acid were also investigated. Increases in the catalyst and reactant loadings were favorable for the decarboxylation of 2,4,5-trifluorbenzoic acid; however, a high catalyst loading was not favorable. A reusability test with Cu2O re...

Decarboxylation of tetrafluorophthalic acid in NH3-enriched high temperature liquid water

2,3,4,5-Tetrafluorobenzoic acid is an important pharmaceutical intermediate. A green technology for the decarboxylation of tetrafluorophthalic acid to 2,3,4,5-tetrafluorobenzoic acid in NH3-enriched high temperature liquid water (HTLW) was developed. Tetrafluorophthalic acid could undergo the decarboxylation with the catalysis of NH3 to 2,3,4,5-tetrafluorobenzoic acid in HTLW. A conversion of 98.1% and selectivity of 96.5% were achieved at 453.15K for 1.5h with an ammonia concentration of 13.4mmol/L. The effects of ammonia concentration, initial concentration of reactant and reaction temperature were then investigated and correlated using a derivated equation. The results indicated that adequate addition of ammonia could adjust the pH of the reaction medium into 2.2–2.4, where the dominant form of the decarboxylation is the monovalent anion. Moreover, the kinetic data at different temperatures were fitted by a first-order equation, and the rate constants at each temperature and an activation energy of 190kJ/mol were obtained.

P-38 粉砕と高温高圧水を利用した木質リグニンからのフェノール化合物回収(CNF・リグニン,ポスター発表)

P-38 粉砕と高温高圧水を利用した木質リグニンからのフェノール化合物回収(CNF・リグニン,ポスター発表)

The reaction mechanism of polyalcohol dehydration in hot pressurized water.

The use of high-temperature liquid water (HTW) as a reaction medium is a very promising technology in the field of green chemistry. In order to fully exploit this technology, it is crucial to unravel the reaction mechanisms of the processes carried out in HTW. In this work, the reaction mechanism of 2,5-hexanediol dehydration in HTW has been studied by means of three different ab initio simulations: the string method, metadynamics and molecular dynamics in real time. It is found that the whole reaction involving protonation, bond exchange and deprotonation occurs in a single step without a stable intermediate. The hydrogen bonded network of the surrounding water has a vital role in assisting an efficient proton relay at the beginning and at the end of the reaction. It is confirmed that the reaction is energetically most favorable in the SN2 pathway with an estimated barrier of 36 kcal mol-1, which explains the high stereoselectivity and the reaction rate observed in experiment. The mechanistic insights provided by our study are relevant for a prominent class of reactions in the context of sustainable biomass processing, namely dehydration reactions of polyalcohol molecules.

Depolymerization of Poly(butylene terephthalate) into Terephthalic Acid and Tetrahydrofuran in High-temperature Liquid Water

Abstract Poly(butylene terephthalate) (PBT) was decomposed into terephthalic acid (TPA) and tetrahydrofuran (THF) in high-temperature liquid water above 498 K. THF was obtained by the dehydration of the monomer, 1,4-butanediol (1,4-BDO). The yields of TPA, THF, and 1,4-BDO were 98%, 80%, and 12%, respectively, at 523 K after 1 h of the PBT depolymerization in water. The depolymerization rate was enhanced by the additional TPA, which was one of the products.

Recent progress in catalytic selective dehydration of sorbitol

Recently, the use of renewable biomasses has attracted much attention from academics and industry. Sorbitol is a useful biomass- derived chemical that can be converted to high-added-value products; it can be conveniently obtained from cellulose via glucose. Isosorbide and 1,4-anhydrosorbitol, which can be produced by dehydration of sorbitol, are potentially important bio-based industrial chemicals. Sorbitol can be transformed into 1,4-anhydrosorbitol and isosorbide through acid-catalyzed selective dehydration. The catalyst acidity is the most important factor in acid-catalyzed dehydration reactions. It has been observed that strong acidity is favorable for producing isosorbide. Various homogeneous and heterogeneous catalysts have been developed for sorbitol dehydration, depending on the desired products. Mineral acids such as sulfuric acid and hydrochloric acid, and metal halides such as SnCl4 and AlCl3 are efficient catalysts for sorbitol dehydration. However, processes using homogeneous acids have drawbacks from environmental and safety perspectives. Moreover, homogenous catalyst separation from the reaction mixture is cumbersome, which may add extra costs to commercial synthesis. Various solid catalysts such as zeolites, metal(IV) phosphates, layered niobium- molybdate, tungstophosphoric acids supported on various metal oxides, metal oxides modified with phosphoric acid, a superhydrophobic mesoporous polymer-based acid catalyst, and resins (amberlyst-15) have recently been tested in the selective dehydration of sorbitol. In addition, high-temperature liquid water has attracted much attention as a promising reaction medium for sorbitol dehydration. Future prospects for catalytic dehydration of sorbitol are summarized.

Continuous dehydration of 1,4-butanediol in flowing liquid water with carbon dioxide

Dehydration of 1,4-butanediol to tetrahydrofuran in high-temperature liquid water with carbon dioxide using a flow reactor system was studied. Tetrahydrofuran was continuously obtained and the yield was increased by the addition of carbon dioxide into the flowing solution.

Biomass Valorization in High-temperature Liquid Water

Biomass Valorization in High-temperature Liquid Water

Intramolecular dehydration of mannitol in high-temperature liquid water without acid catalysts

Dehydration reactions in high-temperature liquid water.