Positive Displacement Two-Stage Hybrid Power Machine without Gas Cap with Profiled Working Chamber in Second Compression Stage: Influence Analysis of Operating Parameters on Work Processes

A numerical simulation of influence of the discharge pressure of the second stage compressor section and the crankshaft speed of the first stage pump section is presented based on a previously developed mathematical model of the working processes of a positive displacement two-stage hybrid reciprocating power machine (PDHRPM) without a gas cap and having a second-stage profiled working chamber. The stability of working processes of the machine is confirmed in all changes in its operating parameters. The use of a profiled working chamber allows the heat exchange surface to be increased, which leads to an increase in the amount of heat withdrawn during compression and its approximation to isothermality. When considering the dynamics of the fluid in the machine, relative pressure loss along the length of the pipelines and working chambers is most significant (50 to 70 % of all pressure losses), while inertial head loss is about 30 % and the head loss due to local resistances is very small, comprising 2 to 3 %. In the structure of relative inertial losses, the leading position is occupied by inertial head losses in the connecting pipeline, comprising 98 to 99 %, while the comparable inertial head losses in the machine stages amount to ~1 %.