Search

The effect of liquid compressibility in the two-stage piston hybrid positive-displacement machine with a liquid piston was considered. Based on the volume conservation equation, we developed a calculus methodology for the liquid compressibility during gas compression in the second stage of the compressor section. A numerical experiment made it possible to establish that some parameters have the greatest effect on the relative decrease in the height and velocity of the liquid layer. These parameters are the degree of pressure ratio; pipeline length; the polytropic index of the compression; the number of crankshaft revolutions. We found that the relative decrease in the liquid layer height is within 1 %, and the relative decrease in the liquid piston velocity is within 5 %. The paper analyses the liquid piston compressibility influence on the thermodynamic efficiency of the compression process and compressor performance.

A generalized approach to the analysis of feed unevenness in positive displacement pumps is considered. A procedure for calculating the working processes in chambers of constant or variable volume in a discharge line as well as a nonstationary one-dimensional gas flow in a discharge pipe is developed. Boundary conditions are defined. Nonstationary one-dimensional flow is calculated by the method of “characteristics.” By means of a numerical experiment, variations in the pressure in the working chambers and along the length of the pipe as a function of the turning angle of the shaft are established. On the basis of pressure fluctuation in a discharge pipe, it is proved that the feed unevenness significantly exceeds the magnitude of the feed unevenness determined when the pressure fluctuation is not taken into account. [ABSTRACT FROM AUTHOR]

A mathematical model of the working processes in positive-displacement machines designed to compress two-phase, two-component working fluids is developed on the basis of the general laws of conservation of energy, mass, volume and motion. A mathematical model of the working processes of a hybrid piston power machine where there is a layer of liquid above the piston in the compressor section is given. Two open thermodynamic systems (gas and droplet liquid) in the presence of deformation and thermal interactions are considered. [ABSTRACT FROM AUTHOR]