Gas compression in a cylinder to high pressure: Analysis of key problems and solutions for overcoming them

Along with an increase in the angular velocity of the crankshaft rotation, one of the most effective ways to improve the mass-dimensional characteristics of piston compressors is to increase the ratio of discharge pressure to suction pressure. It allows reducing the number of stages up to a transition to single-stage (single-cylinder) gas compression. The aim of the research is to identify and systematize the thermodynamic and strength limitations that determine the achievable ultimate parameters of single-stage gas compression to high pressure and to justify technical solutions for their compensation. The article examines methods for overcoming negative phenomena in single-stage compression, which primarily consists in improving the cooling of the compressed gas, using a liquid piston to prevent leakage and eliminate clearance volume, as well as applying new non-flammable lubricants. The elimination of clearance volume and compressed gas leakage ensures an increase in the indicated isothermal efficiency and volumetric efficiency when compressing gas in a single stage to high pressure. On the other hand, overcoming strength-related problems consists in developing designs with minimal forces acting on the piston crown and employing new high-strength structural materials. Therefore, the feasibility of compressing gas to high pressure (10 MPa and above) in a single compressor stage has been established, which allows replacing multi-stage compression with a single-stage process. The most efficient approach to cool the cylinder-and-piston assembly components is to integrate the compressor and the pump into a unified piston-type hybrid positive-displacement power machine.