Gas solubility test bench
The gas solubility test bench is used to estimate the Bunsen absorption coefficient of gases such as nitrogen in hydraulic fluids as well as other liquids, e.g., conventional and bio-hybrid fuels. With indirect measurements of pressure, temperature and volume, the amount of dissolved gas can be precisely determined.
Test bench setup
The test bench consists of a pressure chamber filled with the sample liquid and gas, and a piston to alter the gaseous and the liquid phase’s volume. To seal the piston and chamber against each other, a special sealing system is used, which is also suitable for aggressive media and solvents.
Measurement process
After filling the pressure chamber with the sample liquid, a vacuum pump is used to evacuate the air from the pressure chamber. The sample gas is then let in the pressure chamber. The gearbox and the threaded rod transforms the rotational movement of the hand wheel into linear movement. This reduces the chamber’s overall volume and pressurizes the sample liquid and the sample gas within the chamber. During the measurement, a variety of sensors allow to record all quantities, which are necessary for the calculation of the Bunsen absorption coefficient.
Results for fuels
With help of the previously described measurement setup, the deduced equations and density data from the literature, the Bunsen absorption coefficient of Diesel, 1,3-Dioxolane and Dimethoxymethane was determined. The individual measuring points are highlighted with circular markers. The solid lines are representative for the exponential fit based on the Krichevsky-Kasarnovsky equation. According to this equation, a maximum for the dissolved chemical amount exists. This results in a decrease of dissolved gas content beyond a certain pressure threshold. The following figure shows this pressure for diesel, dimethoxymethane and 1,3-dioxolane at 293.15 K.