• Title/Summary/Keyword: thermodynamic equations

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A Consideration of Analytical Thermodynamic Modeling of Bipropellant Propulsion System

  • Chae, Jong-Won
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.243-246
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    • 2008
  • This paper is to consider analytical thermodynamic modeling of bipropellant propulsion system. The objective of thermodynamic modeling is to predict thermodynamic conditions such as pressures, temperatures and densities in the pressurant tank and the propellant tank in which heat and mass transfer occur. In this paper also it shows analytic equations that calculate the evolution of ullage volume and interface areas. Since the ullage interface areas are time-varying,(the liquid propellant volume decreases as the rocket engine is firing; the change of ullage volume correspond to the change of liquid propellant volume) for a numerical convenience non-dimensionalized correlations are commonly used in most literatures with limitations; a few percentages of inherent error. The analytic equations are derived from analytic geometry, subsequently without inherent error. Those equations are important to calculate the heat transfer areas in the heat transfer equations. It presents the comparison result of both analytic equations and correlation method.

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Prediction of the Liquidus Temperature Curve for Hypoeutectic Al-Si-Cu-Mg Alloy (아공정 Al-Si-Cu-Mg 합금의 액상선 온도 곡선 예측)

  • Kim, Keunhak;Park, Dongsung;Oh, Seung-Jin;Jeon, Junhyub;Yoon, Sang-Il;Kim, Ki-Sun;Kim, Tae-Young;Lee, Seok-Jae
    • Journal of the Korean Society for Heat Treatment
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    • v.31 no.6
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    • pp.300-306
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    • 2018
  • In the present study we proposed new equations to predict the liquidus temperature curve for hypoeutectic Al-Si-Cu-Mg alloy. A thermodynamic simulation was carried out to calculate the liquidus temperature, eutectic temperature and eutectic Si concentration with different Si, Cu, and Mg contents in hypoeutectic Al-Si alloys. Regressed equations were derived using the thermodynamic simulation results by multiple regression analysis. The proposed equations were compared with the equations reported previously by other researchers and agreed better with the experimental data. The addition of Cu and Mg lowered the eutectic temperature. The eutectic Si concentration was decreased by adding Cu whereas that was increased by adding Mg. Al-Si binary phase diagram was successfully predicted with a consideration of the effect of Cu and Mg addition by using the proposed equations.

Cubic Equation of State Analysis for the Prediction of Supercritical Thermodynamic Properties of Hydrocarbon Fuels with High Critical Compressibility Factor (고 임계 압축인자를 갖는 탄화수소 연료의 초임계 열역학적 물성 예측을 위한 상태방정식 분석)

  • Jae Seung Kim;Jiwan, Seo;Kyu Hong Kim
    • Journal of the Korean Society of Propulsion Engineers
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    • v.26 no.5
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    • pp.24-34
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    • 2022
  • In order to predict the cooling performance of a regenerative cooling channel using hydrocarbon fuel operating in the supercritical region, it is essential to predict the thermodynamic properties. In this study, a comparative analysis was performed on two-parameter equations of state (SRK(Soave-Redlich-Kwong), PR(Peng-Robinson) equations of state) and three-parameter equations of state (RK-PR equations of state) to appropriately predict density and specific heat according to the critical compressibility factor of polymer hydrocarbons. Representatively, n-dodecane fuel with low critical compressibility factor and JP-10 fuel with high critical compressibility factor were selected, and an appropriate equation of state was presented when predicting the thermodynamic properties of the two fuels. Finally, the prediction results of density and specific heat were compared and verified with NIST REFPROP data.

Application of Procedures to Calculate Thermodynamic Properties of Carbon Dioxide, HFC-134a and HCFC-22

  • Park Hyoung Joon;Park Kyoung Kuhn
    • International Journal of Air-Conditioning and Refrigeration
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    • v.12 no.4
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    • pp.176-183
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    • 2004
  • Systematic methods to calculate thermodynamic properties of carbon dioxide, HFC-134a and HCFC-22 are presented. First, application of a basic method to identify the saturation state with given temperature or pressure is attempted and the feasibility of auxil­iary equations is tested. Next, detailed procedures are suggested to tell a phase when tem­perature/pressure and another property are specified. Finally the Newton-Raphson method is applied to calculate unknown thermodynamic properties fixing the state with the two inde­pendent properties specified. The procedures described here are utilized to develop a computer program, which is used to find the relation between temperature and pressure with maximum isobaric heat capacity for super-critical carbon dioxide.

Application of Procedures to Calculate Thermodynamic Properties of Carbon Dioxide, HFC-l34a and HCFC-22 (이산화탄소, HFC-l34a, HCFC-22의 열역학적 상태량 계산 절차의 응용)

  • 박형준;박경근
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.5
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    • pp.389-396
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    • 2003
  • Systematic methods to calculate thermodynamic properties of carbon dioxide, HFC-l34a and HCFC-22 are presented. First, application of a basic method to identify the saturation state with given temperature or pressure is attempted and the feasibility of auxiliary equations is tested. Next, detailed procedures are suggested to tell a phase when temperature/pressure and another property are specified. Finally Newton-Raphson method is applied to calculate unknown thermodynamic properties fixing the state with the two independent properties specified. The procedures described here are utilized to develop a computer program, which is used to find the relation between temperature and pressure with maximum isobaric heat capacity for super-critical carbon dioxide.

A Review of Surface Energy of Solid Electrodes with Emphasis on Its Controversial Issues in Interfacial Electrochemistry

  • Go Joo-Young;Pyun Su-Il
    • Journal of the Korean Electrochemical Society
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    • v.7 no.4
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    • pp.211-219
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    • 2004
  • A classical Lippmann equation valid for liquid electrodes can not describe the interfacial properties of solid electrodes due to the elastic surface strain on solid electrodes. Although there have been many attempts to derive the thermodynamic equations for solid electrodes Outing the past few decades, their validity has been still questioned by many researchers. In practice, although there are various experimental techniques to measure surface energy of solid electrodes, the results obtained by each technique are rather inconsistent due to the complexity of the surface strain on solid electrodes. This article covers these controversial issues in surface energy of solid electrodes. After giving brief summaries of the definition of the important thermodynamic parameters and the derivation of the thermodynamic equations for solid electrodes, the several experimental methods were introduced for the measurement of surface energy of solid electrodes. And then we discussed in detail the inconsistent results in the measurement of the potential of zero charge (pac) and the potential of electrocapillary maximum (ecm).

Design of Heat Dissipation System for 400kW IGBT Inverter (400kw급 IGTB 인버터용 방열 시스템 설계)

  • Lee Jin-Woo
    • Proceedings of the KIPE Conference
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    • 2003.07a
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    • pp.10-14
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    • 2003
  • This paper deals with the design of heat dissipation system using the forced air cooling method. It suggests the method of appropriately dividing the whole thermodynamic system into analytical subsystems and also presents the correspondent analytic or experimental equations to subsystems. The experimental results on the designed thermodynamic system for 400kw 1GBT inverter show the validity of the proposed design method in the steady state.

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Linear Relationships between Thermodynamic Parameters (Part I) Theoretical (熱力學 函數間의 直線關係 (第1報) 理論)

  • Ikchoon Lee
    • Journal of the Korean Chemical Society
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    • v.7 no.3
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    • pp.211-215
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    • 1963
  • Inter-relationship between the Hammett equation and the linear enthalpy-entropy effect has been discussed by deriving a new set of equations; ${\Delta}{\Delata}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^{\neq}$ and ${\Delta}{\Delta}F^{\neq}=a{sigma}+(b-T){\Delta}{\Delta}S^{\neq}$ where a = -1.36p. Theoretical analysis show that the Hammett, Leffler and Brown equations are special limited forms of these general equations. A necessary and sufficient test of substituent effect can thus be provided by the plot of $({\Delta}{\Delta}H^{\neq}-a{\sigma)$ versus ${\Delta}{\Delta}S^{\neq}$.

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Dynamics of multilayered viscoelastic beams

  • Roy, H.;Dutt, J.K.;Datta, P.K.
    • Structural Engineering and Mechanics
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    • v.33 no.4
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    • pp.391-406
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    • 2009
  • Viscoelastic materials store as well as dissipate energy to the thermal domain under deformation. Two efficient modelling techniques reported in literature use coupled (thermo-mechanical) ATF (Augmenting Thermodynamic Fields) displacements and ADF (Anelastic Displacement Fields) displacements, to represent the constitutive relationship in time domain by using certain viscoelastic parameters. Viscoelastic parameters are first extracted from the storage modulus and loss factor normally reported in hand books with the help of Genetic Algorithm and then constitutive relationships are used to obtain the equations of motion of the continuum after discretizing it with finite beam elements. The equations of motion are solved to get the frequency response function and modal damping ratio. The process may be applied to study the dynamic behaviour of composite beams and rotors comprising of several viscoelastic layers. Dynamic behaviour of a composite beam, formed by concentric layers of steel and aluminium is studied as an example.

Thermodynamic Properties of the Polymer Solutions

  • Lee, Woong-Ki;Pak, Hyung- Suk
    • Bulletin of the Korean Chemical Society
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    • v.6 no.6
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    • pp.337-343
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    • 1985
  • A statistical mechanical approach to elucidate the solvent effects on the high polymer solutions has been carried out on the basis of the simple model of liquids improved by Pak. In our works, the partition function of the polymer solutions is formulated by the lattice model and our simple treatment of liquid structures. For the ideal polymer solutions proposed by Flory, thermodynamic functions of the polymer solutions are obtained and equations of mixing properties and partial molar quantities are derived from the presented partition function of the polymer solutions. Partial molar quantities are calculated for the rubber solutions in carbon disulfide, benzene and carbon tetrachloride. Comparisons have been made between our equations and those of Flory's original paper for partial molar properties of the rubber-benzene system. Comparing the experimental data of the osmotic pressure of polystyrene-cyclohexane system with our calculated values and those of Flory's, our values fit to the agreeable degrees better than those of Flory's.