• Title, Summary, Keyword: Thermodynamic parameters

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Performance Characteristics of a Combined Regenerative Ammonia-Water Based Power Generation Cycle Using LNG Cold Energy (LNG 냉열을 이용하는 암모니아-물 복합 재생 동력 사이클의 성능 특성)

  • Kim, Kyounghoon;Oh, Jaehyeong;Jeong, Youngguan
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.6
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    • pp.510-517
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    • 2013
  • The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

The Theory of Significant Structure of Liquids : A New Method of Fixing Parameters (액체의 구조에 관하여 -새로운 Parameter 결정법-)

  • Hyungsuk Park;Seihun Chang
    • Journal of the Korean Chemical Society
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    • v.7 no.2
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    • pp.174-178
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    • 1963
  • The new method to determine the parameters in the liquid partition function of H. Eyring and co-workers is proposed, in which method the equilibrium condition of the three phases and the boundary condition of the liquid partition function at the triple point are used. The calculated thermodynamic properties using the new determined parameters are agreed well with the observed values.

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Pridiction of Adsorption Equilibrium for Binary Gas Mixtures on Cation Exchanged Forms of ZSM-5

  • Going Yim;Chai Suck Yim
    • The Journal of Engineering Research
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    • v.6 no.2
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    • pp.85-98
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    • 2004
  • The adsorption equilibrium data for the binary gas mixture system from the pure gas adsorption data of carbon dioxide and ethylene on ZSM-5 prepared were predicted. The binary gas mixture adsorption data have been examined against predicted values by two models-the vacancy solution model(VSM) and the statistical thermodynamic model(STM), using parameters obtained from the single component isotherm. The binary gas mixture data for the carbon dioxide-ethylene system were obtained for cation exchanged forms of ZSM-5 for the gas phase carbon dioxide mole fraction of 0.752 at $37^{\circ}C$ and 1 atm. The experimental adsorption phase diagrams were obtained for carbon dioxide-ethylene on sodium form ZSM-5 synthesized. The single component adsorption isotherms for carbon dioxide and ethylene were also obtained for this zeolite. The single component data were used to obtain parameters derived in two models. These parameters were, in turn, used to predict the binary mixture isotherms for this zeolite. Both the vacancy solution and the statistical thermodynamic models give satisfactory predictions of adsorption phase diagrams for the binary gas mixtures of carbon dioxide and ethylene on sodium exchanged ZSM-5. Also the correlation between the experimental data and the predicted values is generally in good agreement. The system appears to show ideal behavior with a relatively constant separation factor. The slight increase in adsorption capacity with an increase in ionic radius is due, in part, to the higher polarizability associated with larger cations.

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Linear Relationships between Thermodynamic Parameters. Part 6 Solvent Effect on Chloride Exchanges in Benzyl Chloride (열역학함수간의 직선관계 (제6보) 염화벤질의 염소교환에 미치는 용매효과)

  • Lee, Ik-Choon;Park, Yong-Ja
    • Journal of the Korean Chemical Society
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    • v.12 no.4
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    • pp.160-162
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    • 1968
  • Rate constants and activation parameters have been petermined for the chloride exchanges of benzyl chloride in 60, 70, 80 and 90 vol.% ethanol-water solutions. Results showed a good linearity when appiled to our general equation. The significance of this linear fit has been discussed in conjunction with the Dewar's relation which was derived from the PMO method.

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Inhibition Effect of Nevirapine an Antiretroviral on the Corrosion of Mild Steel Under Acidic Condition

  • Bhat, J. Ishwara;Alva, Vijaya D.P.
    • Journal of the Korean Chemical Society
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    • v.55 no.5
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    • pp.835-841
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    • 2011
  • Corrosion inhibition of mild steel by nevirapine, an antiretroviral has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy technique and weight loss methods. The experimental results suggested, nevirapine is a good corrosion inhibitor for mild steel in 1M hydrochloric acid medium and the inhibition efficiency increased with increase in inhibitor concentration. The kinetic parameters for corrosion process and thermodynamic parameters for adsorption process were calculated and discussed. The adsorption of the inhibitor on the surface of mild steel followed Langmuir adsorption isotherm.

Determinationof Optimal Cutting Condition for High Quality Cutting Surface (표면품질 향상을 위한 레이저 절단조건)

  • 황경현
    • Proceedings of the Optical Society of Korea Conference
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    • pp.37-41
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    • 1990
  • The quality of cutting surface such as surface roughness, heat affected zone, serf width can be improved by controlling the parameters of cuting process. These parameters includes cutting velocity, laser beam power, material depth and assistant gas. Thermodynamic analysis and systematical experiments are attempted to pedict and determine the optimal cutting condition. There exists the optimal cutting condition to ensure high quality surface. Under this operation, the minimum surface roughness of the mild steel, the stainless steel and the titanium becomes 3.8${\mu}{\textrm}{m}$ 13${\mu}{\textrm}{m}$ and 10${\mu}{\textrm}{m}$ respectively.

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ICE GROSS HEAT RELEASE STRONGLY INFLUENCED BY SPECIFIC HEAT RATIO VALVES

  • Lanzafame, R.;Messina, M.
    • International Journal of Automotive Technology
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    • v.4 no.3
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    • pp.125-133
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    • 2003
  • Several models for the evaluation of Gross Heat Release from the internel combustion engine (ICE) are often used in literature. One of these is the First Law - Single Zone Model (FL-SZM), derived from the First Law of Thermodynamic. This model present a twice advantage: first it describes with accuracy the physic of the phenomenon (charge heat release during the combustion stroke and heat exchange between gas and cylinder wall); second it hat a great simplicity in the mathematical formulation. The evaluation of Heat Release with the FL-SZM is based on pressure experimental measurements inside the cylinder, and ell the assumption of several parameters as the specific heat ratio, wall temperature, polytropic exponent for the motored cycle evaluation, and many others. In this paper the influence of gases thermodynamic properties on Cross Heat Release has been esteemed. In particular the influence of an appropriate equation for k=k(T) (specific heat ratio vs. temperature) which describes the variations of gases thermodynamic properties with the mean temperature inside the cylinder has been evaluated. This equation has been calculated by new V order Logarithmic Polynomials (VoLP), fitting experimental gases properties through the least square methods.

Thermodynamic Interactions Among Carbon, Silicon and Iron in Carbon Saturated Manganese Melts (탄소 포화 Mn 합금 용액내 C, Si 및 Fe 사이의 열역학적 상호작용)

  • Paek, Min-Kyu;Lee, Won-Kyu;Jin, Jinan;Jang, Jung-Mock;Pak, Jong-Jin
    • Korean Journal of Metals and Materials
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    • v.50 no.1
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    • pp.45-51
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    • 2012
  • Thermodynamics of carbon in manganese alloy melts is important in manufacturing low carbon ferromanganese and silico-manganese alloys. In order to predict the carbon solubility in liquid $Mn-Si-Fe-C_{sat}$ alloys as a function of melt composition and temperature, thermodynamic interactions among carbon, silicon and iron in carbon saturated liquid manganese should be known. In the present study, the effects of silicon and iron on the carbon solubility in Mn-Si, Mn-Fe and Mn-Si-Fe melts were measured in the temperature range from 1673 to 1773 K. The carbon solubility decreases significantly as silicon and iron contents increase in liquid manganese alloy. The interaction parameters among carbon, silicon and iron in carbon saturated liquid manganese were determined from the carbon solubility data and the Lupis' relation for the interaction coefficient at constant activity.

Kinetic and Thermodynamic Analysis of AChE Inhibition of Solvent Extract Fractions from Inonotus obliquus (차가버섯 용매추출분획의 Acetylcholinesterase 저해활성에 대한 동역학 및 열역학적 해석)

  • Kim, Hak-Kyu;Hur, Won;Hong, Eok Kee;Lee, Shin-Young
    • Food Engineering Progress
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    • v.15 no.4
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    • pp.289-296
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    • 2011
  • Twenty four fractions by solvent extraction and/or acid precipitation from fruit body and culture broth of Inonotus obliquus were prepared, and their inhibitory effect against acetylcholinesterase (AChE) was investigated. Among these fractions, acid (1 M HCl) precipitates from cell-free culture broth and fruit body exhibited the highest inhibitory effect on AChE in vitro. Acid precipitates inhibited AChE activity in a concentration-dependant manner and $IC_{50}$ values of both acid precipitates were 0.53 mg/mL. The inhibition pattern was general non-competitive inhibition. The energetic parameters were also determined by dual substrate/temperature design. Both acid precipitates increased the values of Ea, ${\Delta}H,/;{\Delta}G$ and ${\Delta}H^{\ast}$ decreasing the value of ${\Delta}S$ for AChE. The results implied that the acid precipitates from I. obliquus increased the thermodynamic barrier, leading to the breakdown of ES complex and the formation of products as inhibitory mechanism.