• Title, Summary, Keyword: Thermodynamic parameters

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A Study on Performance Diagnostics of Turbo-Shaft Engine Using Thermodynamic Sensitivity (열역학적 민감도를 이용한 터보축 엔진의 성능진단 연구)

  • Lee Dae-Won;Roh Tae-Seong;Choi Doeg-Whan
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.289-292
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    • 2005
  • Because of accumulation of operation time, the performance of main components(compressor, combustor, turbine, etc.) come to be deteriorated in gas-turbine engine. So, high reliability and minimun of expense are important problem for engine manufacturer and user in operation of gas-turbine engine. In this study, the diagnostic code of the engine performance using the thermodynamic sensitivity between the sensed parameters and the health parameters has been developed without an application of the commercial program. The single performance deterioration of the turbo-shaft engine has been estimated with this code.

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Acid green-25 removal from wastewater by anion exchange membrane: Adsorption kinetic and thermodynamic studies

  • Khan, Muhammad Imran;Ansari, Tariq Mahmood;Zafar, Shagufta;Buzdar, Abdul Rehman;Khan, Muhammad Ali;Mumtaz, Fatima;Prapamonthon, Prasert;Akhtar, Mehwish
    • Membrane Water Treatment
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    • v.9 no.2
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    • pp.79-85
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    • 2018
  • In this work, batch adsorption of anionic dye acid green-25 (AG-25) from aqueous solution has been carried out at room temperature using anion exchange membrane (DF-120B) as a noval adsorbent. The effect of various experimental parameters such as contact time, membrane dosage, ionic strength and temperature on the adsorption of dye were investigated. Kinetic models namely pseudo-first-order, pseudo-second-order, Elovich, liquid film diffusion, Bangham and modified freundlich models were employed to evaluate the experimental data. Parameters like adsorption capacities, rate constant and related correlation coefficients for every model are calculated and discussed. It showed that adsorption of AG-25 onto DF-120B followed pseudo-first-order rate expression. Thermodynamic study indicates that adsorption of AG-25 onto DF-120B is an exothermic and spontaneous process.

Kinetics and Thermodynamic Studies on the Reaction of Cysteine with Cinnamaldehyde

  • Kim, Tae-Rin;Yun, Se-Joon;Park, Byung-Bin
    • Bulletin of the Korean Chemical Society
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    • v.7 no.1
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    • pp.25-29
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    • 1986
  • The reaction of cysteine with cinnamaldehyde have been studied kinetically and thermodynamically. It was found that the reaction proceeds in two steps; formation of the monoadduct by a Michael type addition followed by the nucleophilic attack of the second cysteine to the carbonyl carbon of the monoadduct to afford the thiazolidine derivative. A reaction profile for the reaction of cysteine with cinnamaldehyde was constructed based on the thermodynamic parameters analyzed for the forward and the reverse reactions. It was assumed that the second step of this reaction accompanies an intermediate, a Schiff base.

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On Stability of the Steady State, Thermodynamic Stabililty and Corresponding States in Rheology of Dense Simple Fluids$^\dag$

  • Ohr, Young-Gie;Eu, Byung-Chan
    • Bulletin of the Korean Chemical Society
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    • v.7 no.3
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    • pp.204-210
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    • 1986
  • It is shown that the linear stability coincides with the thermodynamic stability in the case of stress tensor evolution for simple dense fluids even if the constitutive (evolution) equation for the stress tensor is nolinear. The domain of coincidence can be defined in the space of parameters appearing in the constitutive equation and we find the domain is confined in an elliptical cone in a three-dimensional parameter space. The corresponding state theory in rheology of simple dense fluids is also further examined. The validity of the idea is strengthened by the examination.

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Thermodynamic model of one of the super heaters and the related spray in the Nekka power plant and Presenting SCO method to control boiler temperature

  • Zalloi, Mehdi;Barghandan, Saeed;Badamchizadeh, M.A.
    • 제어로봇시스템학회:학술대회논문집
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    • pp.129-133
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    • 2005
  • In this paper, first the thermodynamic model is presented to one of the super heaters and sprays of the Nekka power plant and then its unknown parameters are identified according to the registered data of the power plant. SCO control method is introduced to control the external steam temperature of super heater. Finally the conventional method in power plant for controlling external steam temperature of super heater is compared with new method and their performances are presented..

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Influence of Sulfate on Thermodynamic Modeling of Hydration of Alkali Activated Slag (알칼리 활성 슬래그의 열역학적 수화모델링에 대한 황산염의 영향)

  • Lee, Hyo Kyoung;Park, Sol-Moi;Kim, Hyeong-Ki
    • Journal of the Korean Institute of Resources Recycling
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    • v.28 no.1
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    • pp.32-39
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    • 2019
  • The present study investigated hydration of alkali activated slag incorporating sulfate as a form of anhydrite by employing thermodynamic modeling using the Gibbs free energy minimization approach. Various parameters were evaluated in the thermodynamic calculations, such as presence of sulfide, precipitation/dissolution of AFt/AFm phase, and the effect of oxic condition on the predicted reaction. The calculations suggested no significant difference in the void volume and chemical shrinkage, which might influence the performance of the mixtures, in spite of various changes of the parameters. Although the types of hydration products and their amount varied according to the input conditions, their variations were smaller range than that induced by water-to-binder ratio. Moreover, it did not affect the amount of C-(N-)A-S-H which was the most important hydration product.

Solubility of celecoxib in N-methyl-2-pyrrolidone + water mixtures at various temperatures: Experimental data and thermodynamic analysis

  • Nozohouri, Sarah;Shayanfar, Ali;Cardenas, Zaira Johanna;Martinez, Fleming;Jouyban, Abolghasem
    • The Korean Journal of Chemical Engineering
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    • v.34 no.5
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    • pp.1435-1443
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    • 2017
  • Solubility is one of the most significant physicochemical properties of drugs, and improving the solubility of drugs is still a challenging subject in pharmaceutical sciences due to requirements of enhancing their bioavailability. Celecoxib, according to the biopharmaceutics classification system (BCS), is a class 2 drug, possessing low water solubility (<$5{\mu}g{\cdot}mL^{-1}$) and high permeability. Increasing the solubility of this group can lead to improved bioavailability, dose reduction and subsequently, increased efficiency and reduced side effects. In this study, celecoxib solubility was determined in binary mixtures of N-methyl-2-pyrrolidone (NMP)+water at 293.2, 298.2, 303.2, 308.2 and 313.2 K. The solubility of celecoxib is increased with the addition of NMP to the aqueous solutions and reaches a maximum value in neat NMP. In addition, increased temperature leads to enhanced solubility of celecoxib in a given solvent composition. The solubility data of celecoxib in NMP+water at different temperatures were correlated using different mathematical models including, the Jouyban-Acree model and a combination of the Jouyban-Acree and van't Hoff models. Thermodynamic parameters, Gibbs energy, enthalpy and entropy of dissolution processes were performed based on Gibbs and van't Hoff equations. Thermodynamic analysis allowed observing two main entropy or enthalpy-driven dissolution mechanisms, varying according to the composition of aqueous mixtures. Moreover, preferential solvation of celecoxib by water is observed in water-rich mixtures but preferential solvation by NMP was seen in mixtures with similar composition and also in NMP-rich mixtures.

Kinetic and Thermodynamic Studies of Brilliant Green Adsorption onto Carbon/Iron Oxide Nanocomposite (탄소/산화철 나노복합재료의 Brilliant Green 흡착에 대한 반응속도론적, 열역학적 연구)

  • Ahmad, Rais;Kumar, Rajeev
    • Journal of the Korean Chemical Society
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    • v.54 no.1
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    • pp.125-130
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    • 2010
  • In the present work, we have investigated the adsorption efficiency of carbon/iron oxide nanocomposite towards removal of hazardous brilliant green (BG) from aqueous solutions. Carbon/iron oxide nanocomposite was prepared by chemical precipitation and thermal treatment of carbon with ferric nitrate at $750^{\circ}C$. The resulting material was thoroughly characterized by TEM, XRD and TGA. The adsorption studies of BG onto nanocomposite were performed using kinetic and thermodynamic parameters. The adsorption kinetics shows that pseudo-second-order rate equation was fitted better than pseudo-first-order rate equation. The experimental data were analyzed by the Langmuir and Freundlich adsorption isotherms. Equilibrium data was fitted well to the Langmuir model with maximum monolayer adsorption capacity of 64.1 mg/g. The thermodynamic parameters were also deduced for the adsorption of BG onto nanocomposite and the adsorption was found to be spontaneous and endothermic.

Application of thermodynamics to chemical vapor deposition

  • Latifa Gueroudji;Hwang, Nong-Moon
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • pp.1-20
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    • 1998
  • Processing of thin films by chemical vapor deposition (CVD) is accompanied by chemical reactions, in which the rigorous kinetic analysis is difficult to achieve. In these conditions, thermodynamic calculation leads to better understanding of the CVD process and helps to optimise the experimental parameters to obtain a desired product. A CVD phase diagram has been used as guide lines for the process. By determining the effect of each process variable on the driving force for deposition, the thermodynamic limit for the substrate temperature that diamond can deposit is calculated in the C-H system by assuming that the limit is defined by the CVD diamond phase diagram. The addition of iso-supersaturation ratio lines to the CVD phase diagram in the Si-Cl-H system provides additional information about the effects of CVD process variables.

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Finite Element Analysis of Elasto-Plastic Large Deformation considering the Isotropic Damage (the 1st Report) -Development of Elasto-Plastic Damage Constitutive Model- (등방성 손상을 고려한 탄소성 대변형 문제의 유한요소해석(제1보) -탄소성 손상 구성방정식 개발-)

  • 노인식
    • Journal of Ocean Engineering and Technology
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    • v.14 no.2
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    • pp.70-75
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    • 2000
  • In this paper a new constitutive model for ductile materials was proposed. This model can describe the material degradation due to the evolution of isotropic damage during elasto-platic deformation. The plastic flow rule was derived under the framework of thermodynamic approach of continuum damage mechanics(CDM) in which plastic strain hardening parameters and isotropic damage were taken as thermodynamic state variables. And the process to determine material constants for constitutive model using an experimental data was presented.

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