Dissolution behavior of different lubricating oils in liquid and supercritical CO2.

In deep drilling, lubrication and cooling tremendously affect drill life and machining quality. In this work, we investigate on the cryogenic Minimum Quantity Lubrication (cMQL) with oil and liquid or supercritical CO 2. In the drilling process, both fluids are conducted through small flow channels inside the drill to the cutting edge. For a stable process, single-phase conditions are required. Systems of five different lubricants with carbon dioxide are investigated at 25 °C, 40 °C and 60 °C. Investigations are made optically in a view cell at pressures between 60 bar and 300 bar and quantitatively between 60 bar and 250 bar using the static-analytical method. For the application, information on the mixing kinetics of the oils and CO 2 is further required. To get an insight into the flow behavior under pressure, an optically accessible flow duct is presented that resembles the conditions in the real drilling process. [Display omitted] • Observation of phase behavior of ester base oils for MQL up to 300 bar. • Measurement of isotherms of mutual solubility of lubricant and CO 2 up to 250 bar. • Design of a transparent high-pressure flow cell for pressure up to 100 bar. • Observation of two-phase and single-phase flow behavior under variable conditions. • Evaluation of flow behavior and solubility with respect to drilling application. [ABSTRACT FROM AUTHOR]