Development Of A New Lee Kesler Reference Fluid Extended Corresponding States Principle Method for Volumetric Property
ABSTRACT The corresponding states principle (CSP) and the extended-CSP have proven to be valuable tools in the prediction of fluid and mixture properties. However, the accuracy of the application of these principles to property prediction is crucially dependent on the accuracy of the equation of state of the reference fluid or fluids involved. In this work, a new methodology of property prediction is developed and discussed. The revised extended corresponding states method, as developed by Marrucho and Ely [1] is combined with a reformulated (Teja-like) Lee-Kesler approach. The reformulated Lee-Kesler method is used to generate a pseudo-reference fluid, specific to each target fluid, which allows better mapping characteristics with any specified target fluid. This new methodology is tested for the prediction of bulk volumetric properties of non-polar as well as polar fluids (specifically, alternative refrigerants). The results with different pseudo-reference fluids are compared with that of the original Lee-Kesler model and those obtained with n-propane as a single reference fluid. In the case of polar fluids, the prediction of properties is improved if the Taylor series expansion of the compressibility factor in the Lee-Kesler approach is affected in terms of the dipole moment rather than the acentric factor. The details of the combined ．reformulated Lee-Kesler extended corresponding states・ methodology are elucidated. KEY WORDS: density, extended corresponding states, Lee-Kesler, alternative refrigerants 1. INTRODUCTION Accurate methods for calculating thermodynamic and volumetric properties of pure substances and their mixtures are essential in engineering; efficient design, testing and suitability of equipment and processes need to be adequately ascertained and the accurate knowledge of thermophysical properties becomes crucial. The scarcity of available experimental data, especially in regions ：difficult； to measure, has mandated the development of theoretically based estimation tools. The theoretically based estimation tools can broadly be categorized as: fluid specific correlation methods and generalized correlation methods. ... Of the many generalized correlation approaches that have been proposed, the three parameters corresponding states principle (CSP) has proved to be the most powerful method for predicting properties of fluids and mixtures. Generally this principle takes one of two forms: a one-fluid (single reference fluid) version that may incorporate extensions with shape factors or, a multifluid version that usually incorporates two reference fluids. The MFCSP was originally proposed by Pitzer et al [2-4] and later modified by Lee and Kesler [5] to explicitly include a heavy reference fluid and more recently by Teja et al [6,7] to eliminate the need for a simple fluid as one of the references. Extensive reviews of the corresponding states principle as well as the Lee-Kesler model are found in the literature [8,9]. It is noted, however, that irrespective of the sub-method in the CSP field, the reference fluid equations of state are crucial in the accurate prediction of the target fluid properties.