We developed a mathematical model for determining the parameters of mass transfer in the compressor chambers during the processes of compression and discharge. The mass flow rates through the end and radial gaps were determined. Also we analyzed the processes of mass transfer in a clamped volume. We investigated the influence of the number of vanes on the compressor efficiency, taking into account changes in the compressor geometric parameters. We established that overflows through the end surfaces of rotor mainly affect the compressor performance. In order to reduce overflows during the period of discharge, it was proposed to increase the angle of closure of the discharge window at a fixed angle of its opening. The mathematical model allows one to make recommendations on the choice of the optimal number of vanes for a particular design.

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A promising line for upgrading compressors and expansion machines is the use of unlubricated cylinder-piston units, and sometimes other parts of the moving mechanism. This raises a problem over efficient and long-lived seals, which are made of nonmetallic materials having low elastic moduli E.Calculations and test results show that the maximum pressure differences across a single sealing ring are Ap < 3 MPa in the various stages, which means that the low elastic modulus implies that the rings may be deformed.When the rings deform, there are changes in the parameters of the slots between the surfaces through which compressed gas flows: piston ring-cylinder or piston-ring-end surface of piston groove.In general, gas leaks through the seal on three channels (Fig. 1, in which Pl and P2 are the pressures at the inlet and outlet from the slot):-through the ring section fr = ff'Dc~n between the cylinder 3 and the sealing ring 2 with a nominal gap in the slot ~n = ~r; -through the end diffuser channel fe = ~Z(Dc -bg)Sn between the ring and the groove in the piston I with nominal gap in the slot 5 n = ~e; and -through the rectangular section in the sealing ring joint fj [1]. Calculations on the flow rate through the shot usually involve replacing these channels by a single section subject to the condmon f = fr + fe +fj =/r'Dc~n" The nominal equivalent gap 5 n is determined by experiment. To simplify the calculations, one usually assumes a linear variation in the pressure along this channel, which has a constant area of cross section f. The condition f = constant essentially establishes that the gap 5 n is independent of the pressure pattern in the gas flow region. That assumption is correct for metal rings 9 From [2], the effects of the ring height h and gap 5 n on the vertical distribution over the ring are negligible, but when one uses nonmetallic rings, one has to assume that ~n = f(A'), and consequently that the area of the annular slot f* varies over the height of the ring, which may have a substantial effect on the pressure distribution over the height of the ring [2], and also on the actual gas flow rate through the slot and the type of wear on the sealing rings. In the installed state (Fig. 2a), the cross section of the sealing ring is a rectangle of dimensions b x h; with a uniform pressure p on all the faces of the ring, which has previously been pressed on to the cylinder by the expander, the equivalent radial gap ~n may be taken as constant over the height h of the ring. When a compressor or expansion machine operates, there is a gas leak through f*, and the load distribution on the ring corresponds to that shown in Fig. 2b, which we assume for determining the deformation of nonmetallic sealing rings.In the elastic strain range [1, 3], the forces act independently, and the strain in the piston ring from the various factors is equal to the sum of the strains from each of them separately. We estimate the dependence of the sealing ring strain on the gas pressure difference Ap. The ring is firmly pressed on to the...

Studies conducted by the OAO Kompressor on the development of the AGNKS BK-75 in a modular containerized-unit design calculated for the refueling of 75 vehicles per day were reported at international scientific-technical symposiums and conferences on compressor equipment in 1995 and 1996.A prototype AGNKS BK-75 was fabricated in 1996 in cooperation with the OAO Borkhimmash (Borisoglebsk, Voronezh Oblast) in accordance with building instructions developed by OAO Kompressor. Testing of the station began in January 1997 on a test bench developed by OAO Union Borkhimmash. Previously, the station had been adjusted.initially on air, and it has operated on natural gas since August 1997, providing for the refueling of vehicles equipped with gas cylinders.Preliminary testing of the station was completed in November 1997, and it has undergone acceptance testing. The OAO Kompressor and Borkhimmash set about tooling up for the production of experimental-commercial consignments of the AGNKS BK-75 station simultaneously with the acceptance testing. Delivery of the first series of stations is scheduled for the end of 1998 and beginning of 1999.The station can be connected to trunk gas lines and gas-supply networks, wells of small gas fields, sources of mine gas, etc., and is intended for a dense urban setting, small cities, sites at large establishments, and major highways (Fig. I). The area occupied by the containerized-block station is 50 m 2 with allowance for contiguous zones of -450 m 2 in accordance with the PI~U (without the approach ramps and the zones where gas-filling heads are located).The station consists of separate containerized units: inlet cocks, containerized production units (CPU), containerized accumulator units (CAU), and containerized operator units (COU), and an informational-management system with gas-refueling heads. Inlet filters and a moisture separator, a piston compressor driven off an internal-combustion gas engine (ICGE) with gas-cooling systems, a gas-cleaning and -drying unit, pipelines, and pipeline fittings, an automated control system for the station, a universal-exchange ventilation system, and an automated fire-fighting system are located in the CPU.The modular containerized-unit design and total plant readiness of the station ensures its rapid assembly and the possibility of operation at open sites in climatic zones where the temperature ranges from --45~ to +45~ and also in regions with a six-point seismicity as measured on the Richter scale. Use of the ICGE for the compressor drive makes it possible to lower operating expenditures for energy by a factor of two to three and reduce the consumption of electric power from external power grids to 20 kW.A small gas-piston crosshead compressor with a gas-filled casing (Fig. 2), a unit for the drying and cleaning of compressed gas (Fig. 3), and an automated control system for the stati.on were developed during the course of work conducted by OAO Kompressor on the building of a station based on series-produced high-pressure air compressors.In conn...