Comparative Evaluation of Methods for Calculating the Dynamics of Self-Acting Valves in Reciprocating Compressor Units
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COMPARATIVE EVALUATION OF METHODS FOR CALCULATING THE DYNAMICS OF SELF-ACTING VALVES IN RECIPROCATING COMPRESSOR UNITS I. S. Busarov, V. L. Yusha, S. S. Busarov, and R. E. Kobyl’skii
UDC 621.5–1
A comparative analysis of the influence of the law of motion of the plate of a self-acting valve on the calculation of efficiency indicators of the working process of a piston compressor stage, such as the temperature of the discharge gas, the flow rate and the indicated isothermal efficiency, is presented. Long-stroke, low-speed, and high-speed stages are considered. The conducted studies demonstrate the need to apply the methodology for calculating the dynamics of real valves having elastomeric elements in relation to the stages of low-speed long-stroke compressor units, as well as the relevance of additional studies to clarify the individual components of this method. Keywords: compressor stage, long-stroke piston unit, work processes, dynamics of a self-acting valve.
Various approaches to the description of the movement law for the shut-off element of a self-acting valve in a slow-speed long-stroke compressor unit are considered in theoretical studies of operational processes. The obtained results are then compared with those for high-speed stages of compressor units. The difference between a slow-speed long-stroke compressor unit and traditional reciprocating compressor units [1–3] lies in the stage operation mode and the ratio of the piston stroke to the cylinder diameter. The operating modes of the stages in traditional reciprocating compressor units are characterized by a crankshaft rotation velocity of more than 5 rpm [4]. For slow-speed stages, due to the use of linear drives, the concept of “revolution per second” is not applicable and replaced with the “cycle time”, equal to 2–4 s according to [1] and corresponding to a rotation frequency of 0.25–0.5 rps in terms of the adopted dimension. The ratio of the piston stroke to the cylinder diameter for the studied stages is 5–20; however, for the stages of conventional units, this value does not exceed 1 [4]. Such cylinder dimensions, in combination with a relatively long cycle time and intensive external cooling of the cylinder, contribute to an intensification of gas cooling in the working chamber, thereby ensuring a pressure increase in one stage of over 100 [3]. With regard to slow-speed stages, no information is provided about the influence of the accuracy of the mathematical description of the movement law governing the valve shut-off element on the calculation of the operational process [2, 3]. Therefore, the present study is aimed at carrying out numerical experiments on the working processes of slow-speed reciprocating units using various approaches for describing the dynamics of self-acting valves, as well as comparing the results obtained with the parameters of valves in high-speed compressor unit stages. The object of research comprises self-acting poppet valves of a stage reciprocating compressor unit operating without annulus lubrication [4]. Valve des
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