Measurement and prediction method of compressibility factor at high temperature and high pressure

Abstract

In order to get the compressibility factor Z of working fluid under different conditions, experimental measurement method of Z under high pressure and high temperature and data mining method were studied in this paper. Experimental measurement method based on real gas state equation and prediction method based on Least Squares Support Vector Machine were proposed. First, an experimental method for measuring Z at high temperature and high pressure was designed; in this method the temperature, pressure, and density (mass and volume) of corresponding state were measured and substituted into the actual gas equation of state, and then Z can be calculated. Meanwhile, in order to obtain continuous value in T-p plane, Squares Support Vector Machines are introduced to establish the prediction model of Z. Take Hexamethyldisiloxane, for example; the experimental data of Z was obtained using the experimental method. Meanwhile the prediction model of Z, which can be used as calculation function of Z, was established based on those experimental data, and the Z (T: 500 K∼800 K, p:1.3MPa∼2.25 MPa) was calculated by using this calculation function. By comparison with this published data, it was found that the average relative error was 2.14%.