Home About us Contact
|
Home About us Contact | ||
|
|
||
Pure Fluids (pure + fluid)
Selected AbstractsConsiderations about evaporator thermal design in a vapour compression liquid chiller.INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2004Experimental analysis with HFC fluids (R134a, R407C) Abstract In this paper, the predicted performance of a shell-and-tube (1-2) evaporator installed in a vapour compression liquid chiller is analysed. The classical thermal design methods are applied to the evaporator performance with two HFC refrigerants, a pure fluid (R134a) and a zeotropic blend with an appreciable glide (R407C). From the experimental results obtained it is possible to discuss the validation of the simplificatory assumptions usually taken, evaluating the resulting error introduced due to the no consideration of pressure drops and temperature glide (in the case of zeotropic blends) at the evaporator. Concluding that is not possible to consider the behaviour of a zeotropic refrigerant as a pure refrigerant, rejecting the glide. Whereas the assumption of no pressure drops in evaporator, leads to an error of about 5% in cooling capacity calculation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Determination of cubic equation of state parameters for pure fluids from first principle solvation calculationsAICHE JOURNAL, Issue 8 2008Chieh-Ming Hsieh Abstract A new method for estimation of parameters in cubic equations of state from ab initio solvation calculations is presented. In this method, the temperature-dependent interaction parameter a(T) is determined from the attractive component of solvation free energy, whereas the volume parameter b is assumed to be that of solvation cavity. This method requires only element-specific parameters, i.e., atomic radius and dispersion coefficient, and nine universal parameters for electrostatic and hydrogen-bonding interactions. The equations of state (EOS) parameters so determined allow the description of the complete fluid phase diagram, including the critical point. We have examined this method using the Peng,Robinson EOS for 392 compounds and achieved an accuracy of 43% in vapor pressure, 17% in liquid density, 5.4% in critical temperature, 11% in critical pressure, and 4% in critical volume. This method is, in principle, applicable to any chemical species and is especially useful for those whose experimental data are not available. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Prediction of global VLE for mixtures with improved renormalization group theoryAICHE JOURNAL, Issue 1 2006Jianguo Mi Abstract The recently proposed renormalization group (RG) theory is reformulated within the context of density functional theory and applied to predicting global vapor,liquid equilibria (VLE) of Lennard,Jones chain pure fluids and fluid mixtures. An accurate equation based on the solution of the first-order mean-sphere approximation (FMSA) is adopted outside the critical region. Inside the critical region, the direct correlation function of FMSA is incorporated into the new RG transformation to describe the long-range fluctuation, which is conformal to general inhomogeneous studies. The new RG theory is applied to correcting real mixture phase envelopes, as well as corresponding phase diagrams of pure compounds for the critical region. The calculated results are in substantial agreement with those from experiment and molecular simulation both inside and outside the critical region. The new method is highly predictive because no adjustable parameters and no mixing rule are needed for both model and real fluid mixtures. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Density Measurements of Fluids and Their Mixtures at High PressureCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2007A. M. F. Palavra Abstract The principles of the isochoric method are described, as well as the different variants of this method that can be considered according to the technique used to determine the amount of fluid inside the high pressure cell. An automated isochoric apparatus to measure the density of binary mixtures is presented. Accurate isochoric measurements of density of pure fluids, involving molecules like methanol, and mixtures, such as nitrogen plus methane and a multicomponent system with a composition representative of the U.S.A. commercial Gulf Coast natural gas, are analyzed. Moreover, the effect of the thermal degradation of fluids at high temperatures on the accuracy of the density measurements is also discussed. [source] | ||||||||||