Analysis of the Reverse Expansion Process in a Reciprocating Hybrid Power Machine with Two Suction Valves

The paper analyzes the existing design schemes of hybrid power machines with a coolant moving in the jacket space due to the vacuum at the suction and introduces a new design of a single-stage single-cylinder piston hybrid power machine with two suction valves, in which the forced movement of the coolant in the forward direction is provided due to the vacuum at the suction, and in the reverse direction due to the pressure drop of the compressed gas. The analysis of the reverse expansion process allowed us to determine the value of the reduced dead space, which directly affects the volumetric feed rate of the reciprocating compressor and the feed rate in general. The parametric analysis made it possible to determine the influence of the main design and operating parameters on the value of the reduced dead space and accordingly on the volumetric feed rate. The results obtained can be useful in the design and research of reciprocating hybrid power machines with the forced movement of the coolant.

Analysis of the influence of geometric parameters on working processes in a two!stage hybrid power machine of positive displacement without a gas cap with a profiled working chamber of the second stage

A principal scheme is considered and a mathematical model of work processes is developed in a two-stage hybrid power machine of positive displacement without a gas cap with a profiled working chamber of the second stage. The mathematical model is based on the basic laws of conservation of energy, volume and mass for a dropping liquid and a compressible gas in the second stage. The diameter of the supply pipeline and the initial radius of the profiled working chamber in the second stage are selected as the main geometric parameters that have the greatest influence on the work processes. The response functions are found that determine the dynamics of the fluid flow in the machine under study and its main integral characteristics. Keywords: work process, cooling, reciprocating compressor, hybrid power machine of positive displacement, profiled working chamber [email protected]

Development and Research of Crosshead-Free Piston Hybrid Power Machine

This article considers the development and research of a new design of crosshead-free piston hybrid power machine. After verification of a system of simplifying assumptions based on the fundamental laws of energy, mass, and motion conservation, as well as using the equation of state, mathematical models of the work processes of the compressor section, pump section, and liquid flow in a groove seal have been developed. In accordance with the patent for the invention, a prototype of a crosshead-free piston hybrid power machine (PHPM) was developed; it was equipped with the necessary measuring equipment and a stand for studying the prototype. Using the developed mathematical model, the physical picture of the ongoing work processes in the compressor and pump sections is considered, taking into account their interaction through a groove seal. Using the developed plan, a set of experimental studies was carried out with the main operational parameters of the crosshead-free PHPM: operating processes, temperature of the cylinder–piston group and integral parameters (supply coefficient of the compressor section, volumetric efficiency of the pump section, etc.). As a result of numerical and experimental studies, it was determined that this PHPM design has better cooling of the compressor section (decrease in temperature of the valve plate is from 10 to 15 K; decrease in temperature of intake air is from 6 to 8 K, as well as there is increase in compressor and pump section efficiency up to 5%).

An Analysis of Various Cooling Liquids in a Two-Cylinder Single-Stage Piston Hybrid Power Machine with Fluid Flow Due to Vacuum at Suction Based on Experimental Results

This paper examines the use of various types of cooling liquids in a two-cylinder single-stage piston hybrid power machine with fluid flow due to vacuum at suction. Liquids with various basic thermal properties were used as working fluids: distilled water, antifreeze, and transmission oil. Specific heat capacities and dynamic viscosities of these liquids differed from 2 to 10 times. The experimental studies showed that the greatest cooling effect on the cylinder-piston group was observed when using distilled water, and the least — when using transmission oil. The average surface temperature of the working chamber when cooled with water was minimal in the range of 330–340 K. The average surface temperature of the working chamber when cooled with transmission oil was maximum and ranged from 345 to 355 K, i. e. it was about 15 K higher than when cooled with water. The average surface temperature of the working chamber when cooled with antifreeze occupied an intermediate position between the average temperatures of the working chamber when cooled with water and that with transmission oil and was in the range of 335–345 K, i. e. about 5 K higher than when cooled with water.

An Analysis of the Cooling Intensity Effect of a Two-Cylinder Single-Stage Piston Hybrid Power Machine with Fluid Flow Due to Vacuum at Suction on the Working Processes and Indicative Efficiency

In this paper, a new promising scheme of a two-cylinder single-stage piston hybrid power machine with fluid flow due to vacuum at suction is examined. A prototype is developed, and an experimental stand is created. An analysis of the influence of the coolant flow on the working processes of the machine is carried out theoretically and experimentally. The results obtained show that an increase in the coolant consumption leads to a decrease in the input technical work in the process of compression, an increase in the output technical work in the process of decompression, a reduction of the work losses in the process of discharge and an increase of the work losses in the process of suction. Based on the conducted experimental studies it is established that the optimal indicative value of the efficiency for the experimental machine under study is in the range of 300 – 400 ml/min and the relative increase in the indicative efficiency is within 7 %.

An Experimental Study of a Crossheadless Piston Hybrid Power Positive Displacement Machine with Intensive Cooling of the Compressed Gas

Piston hybrid power machines combining the functions of a compressor and a pump in one unit have become widespread, with a new class of machines that do not have a crosshead currently under development. A prototype of such a machine was designed and manufactured based on the new concept of a crossheadless piston hybrid power machine. A plan for conducting a series of experimental studies was developed. The experimental studies confirmed the feasibility of the prototype in the entire range of independent operating parameters (discharge pressure in the compressor section, discharge pressure in the pump section, the number of revolutions of the crankshaft). The effect of operating parameters on the instantaneous and integral characteristics of the compressor and the pump sections of the crossheadless piston hybrid power machine was also assessed through the experimental studies.