Density experimental measurement and prediction method oforganic working fluid at high temperature and high pressure

In order to solve the problem of the density measurement at high temperature and high pressure (HTHP), particularly in a supercritical state, a density measurement method at HTHP was designed and a density prediction method based on least square support vector machine (LSSVM) was proposed. This experimental method was used to measure the density at different (T,p) points firstly. Then, by learning from the experimental data, the density prediction model based on LSSVM (DP-LSSVM) could be established, and the continuous density values in T-p plane could be predicted by DP-LSSVM, especially in supercritical region where the density was difficult to measure by experimental means. Hexamethyldisiloxane was taken for example. By using the proposed method, the density function on T (600-850 K) and p (1.3-2.25 MPa) was obtained, and density in this area could be calculated. By comparing the calculation results with the published data, it is found that the relative error is only 2.4%, the effectiveness of the method is proved.