DEVELOPMENT OF A METHOD FOR THE DETERMINATION OF VISCOSITY OF DIFFERENT SUBSTANCES IN THE SYSTEMS WITH SUPERCRITICAL FLUIDS

Uporaba superkritičnih fluidov vse bolj narašča. V literaturi najdemo veliko podatkov o obnašanju sistema pri določenih pogojih. Zelo malo pa je podatkov za dvofazne sisteme, ki so zelo pomembni za načrtovanje novih industrijskih postopkov. Tako smo v diplomskem delu preizkusili do sedaj neuporabljeno metodo določanja viskoznosti sistema polietilen glikol/CO2 pri različnih tlakih in z različnimi molskimi masami polietilen glikola ter ugotovili, kako oba dejavnika vplivata na viskoznost sistema. Omenjen sistem PEG/CO2 smo preučevali v tlačnem območju od 10 MPa do 35 MPa, pri konstantni temperaturi 333 K. Ugotovili smo, da se gostota sistema PEG/CO2 obnaša kot funkcija tlaka. Vpliv molske mase je precej manjši. Iz diagramov viskoznost/tlak za različne molske mase polietilen glikola je razvidno, da je zmanjšanje viskoznosti bolj izrazito pri nižjih tlakih.Applications supercritical fluids are growing rapidly. In the literature a lot of information about the behavior of the system under certain conditions can be found. On the other hand, there is lack of data for two-phase systems, which are very important for design of new industrial processes. A new method for determining viscosity of system multi-compound systems at elevated pressures has been developed. Viscosity of different molar weight polyethylene glycols has been evaluated after addition of CO2. System of PEG/CO2 was studied in the pressure range of 10 MPa to 35 MPa at a constant temperature of 333 K. The method requires previos knowledge of system density. Density of the system PEG/CO2 behaves as a function of pressure. Influence of the molar weight is much smaller. Diagrams presenting viscosity as a fanction of pressure clearly demonstrate that reduction in viscosity is more pronounced at lower pressures