The Viscosity of n-Decane to High Temperatures of 573 K and High Pressures of 300 Mpa

The dynamic viscosity of liquid n-decane has been measured with the “Oscillating Disk Method” from 293 K to 573 K and from 0.1 MPa to 300 MPa. A high pressure autoclave of 50 mm internal diameter contained between two rigid disks an oscillating stainless steel disk of 44 mm diameter suspended on a platinum-tungsten wire. Pressure was generated with a spindle press filled with a suitable hydraulic fluid separated from the n-decane. Thus heating and pressure variation could be performed at selected constant volumes. The density dependence of the viscosity could be determined.

The viscosity increases at 373 K from 375 to 1602 μPa s in the pressure range from 0.1 to 200 MPa, at 473 K from 200 to 1114 μPa s in the pressure range from 10 to 300 MPa, and at 573 K from 223 to 675 μPa s in the pressure range from 60 to 300 MPa. The mean accuracy of the viscosity measurements is about 1.3 %. A polynomial function describing the viscosity variation with pressure and temperature is given. The maximum average deviation is 0.46 %, the mean average deviation between measured and calculated data is 0.11 %. The viscosity as a function of density is also shown. With Arrhenius plots, the energies of activation are obtained.