Rotary Vacuum Pump Research Articles

The Study Design of a Double-Action Plate Vacuum Pump

Rotary plate vacuum pumps have become widely used as a source of vacuum for milking systems. The main features of a plate vacuum pump include design simplicity, high efficiency, low cost and adaptability to climatic conditions. A plate vacuum pump requires the improvement of specific performance indicators. This refers to the indicator of specific productivity and specific energy intensity. It is possible to improve the vacuum pump by optimizing the design parameters and technological models of operation. The known studies allow the establishment of rational geometric parameters, the number of plates, the ratio of the main dimensions and eccentricity. However, the problem of reducing the degree of uneven air pumping from the vacuum system needs a scientific solution. The use of a vacuum cylinder in a vacuum line of an increased diameter partially solves the problem of vacuum pressure fluctuations. But such a decision requires additional material costs. In addition, the power of a vacuum pump increases to compensate for the pressure losses. In this study, the authors proposed the design of a double-action plate vacuum pump. It was proven that the simultaneous operation of combined rotors with plates shifted by 45° decreased the degree of air pumping by 7.8%. The research results indicated that the productivity of the developed vacuum pump increased by 13.6%. The drive power increased by 12%, and the specific energy intensity was 20% lower than that of vacuum pumps with similar geometric parameters. The relationship between rational kinematic and design parameters of a double-action vacuum pump was established.

Аналіз конструкцій глушників вакуумних насосів

The substantiation of the structural and functional scheme of the muffler filter of the rotary vane vacuum pump, which has the ability to separate oil from air and collect it for further processing, has been completed. The proposed design, due to its design feature, provides sound suppression, reduces noise and has minimal resistance to the movement of the air flow in the middle of the muffler filter. The muffler filter is based on the fact that air, together with the oil that lubricates the vacuum pump nodes, enters the muffler filter through the inlet pipe at a speed of 11...16 m/s, which allows the most complete separation of oil from air. The trajectory of the movement of air in the muffler is described by a helical winding, and therefore, centrifugal force acts on the oil particles in a suspended state, as a result of which the oil particles are thrown to the sieve catcher, the oil is separated from the air and enters the interwall space of the housing and the sieve catcher, and flows down into the oil sump, from where it is drained using a tap. After that, it can be sent for processing, or, after cleaning, enter the pump lubrication system. The oil-free air continues to move over the surface of the screw winding, and due to the change in the pitch of the screw winding, the air decreases its speed, as a result of which the noise level decreases and oil content is cleaned more efficiently. Air passes to the top cover and enters the environment through the outlet pipe. The work establishes a relationship between the pump performance and the design parameters of the muffler filter. In production conditions, it was investigated that the separation of oil from air in the proposed muffler is 93-95%, and the amount of noise reduction is 15-22 dB. The use of a muffler filter implies a decrease in the productivity of the vacuum pump, which is about 1 m3/h, compared to the serial one - 1.28 m3/h. To introduce the muffler filter into production, it is advisable to use the relationship between the performance of the vacuum pump and the structural parameters of the muffler filter and to develop a division into standard sizes.

Impact of Supersonic Flow in Scintillator Detector Apertures on the Resulting Pumping Effect of the Vacuum Chambers

The article describes the combination of experimental measurements with mathematical–physics analyses in flow investigation in the chambers of the scintillator detector, which is a part of the environmental scanning electron microscope. The chambers are divided with apertures by small openings that keep the desirable pressure differences between three chambers: The specimen chamber, the differentially pumped intermediate chamber, and the scintillator chamber. There are conflicting demands on these apertures. On the one hand, the diameter of the apertures must be as big as possible so that they incur minimal losses of the passing secondary electrons. On the other hand, it is possible to magnify the apertures only to a certain extent so the rotary and turbomolecular vacuum pump can maintain the required operating pressures in separate chambers. The article describes the combination of experimental measurement using an absolute pressure sensor and mathematical physics analysis to map all the specifics of the emerging critical supersonic flow in apertures between the chambers. Based on the experiments and their tuned analyses, the most effective variant of combining the sizes of each aperture concerning different operating pressures in the detector is determined. The situation is made more difficult by the described fact that each aperture separates a different pressure gradient, so the gas flow through each aperture has its own characteristics with a different type of critical flow, and they influence each other, thereby influencing the final passage of secondary electrons detected by the scintillator and thus affecting the resulting displayed image.

Validation of inhomogeneous chamber states in rotary positive displacement vacuum pumps

Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are inhomogeneous for rarefied gases due to the movement of the rotors which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. These inhomogeneous chamber states are assumed to be quasi-static in case that the chamber volume is constant with time. Therefore the chamber must not have a connection to the suction or discharge port. This can be modelled with a one-dimensional approach for geometrically abstracted chambers. In order to validate the one-dimensional characteristics in circumferential direction three-dimensional steady state simulations of a working chamber are performed using a Computational Fluid Dynamics (CFD) solver. To improve the accuracy for rarefied gases Maxwell velocity slip boundary conditions are applied. It is shown, that the inhomogeneous chamber states can be approximated by a regression analysis of a dimensionless number. Furthermore the housing clearance and the radial clearance mass flow rates for given boundary conditions are geometrically abstracted and calculated using a one-dimensional model. The new clearance models and the inhomogeneous chamber states are implemented in a chamber model simulation software and results of a test machine are compared to measurements and to previous simulations.

Transient chamber filling in rotary positive displacement vacuum pumps

Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are inhomogeneous for rarefied gases due to the movement of the rotors which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. It is shown that inhomogeneous chamber states cause a non-complete chamber filling. As a result the mass-averaged pressure within the suction chamber is lower than the pressure in the suction port. Due to the non-constant chamber volume over time three-dimensional transient simulations with a Computational Fluid Dynamics (CFD) solver are performed in order to investigate the mass within a geometrically abstracted suction chamber. Based on a dimensionless number, a regression analysis is done to provide a quantitative estimation of this effect by means of analytical calculations. This is implemented in a chamber model simulation software and results of a test machine are compared to measurements and to previous simulations.

Justifying parameters for the automatic servo control system of a rotary plate vacuum pump in the milking machine

The scientific task to improve energy efficiency and ensure the process of vacuum regime stabilization in the operation of milking machines has been solved. A mathematical model of the process of functioning of the servo control system of a rotary plate vacuum pump was built; the numerical modeling of its workflow was carried out. This paper reports the results of experimental studies on the influence of the regime parameters of the rotary plate vacuum pump on the efficiency of its operation, as well as the results of experimental research on the servo control system for the rotary plate vacuum pump. The operational process of the rotary plate vacuum pump HB-1200 for a milking machine was investigated. The influence of mode parameters (rotor speed n and vacuum pressure P) on the performance of the vacuum pump, Qa, vacuum pressure fluctuation, ΔP, and the power consumption of the vacuum pump drive, Np, has been determined. The servo control system of the rotary plate vacuum pump was experimentally investigated based on the developed algorithms of its operation. In a generally accepted algorithm, vacuum fluctuation increases with increasing an airflow rate: at ΔQa=45 l/min – ΔP=2.3 kPa; at ΔQa=90 l/min – ΔP=4.6 kPa; at ΔQa=135 l/min – ΔP=6.4 kPa. Unlike the generally accepted one, the developed algorithm enables a stable vacuum mode with the largest vacuum fluctuation being ΔP=2.4 kPa. For the first time, the functional dependence of the influence of the regime parameters of the rotary plate vacuum pump with its automatic servo control system on the stability of the vacuum regime of a milk-vacuum system in the milking machine was established. The results can be applied when improving milking machines in terms of ensuring the stabilization process of the vacuum regime.

Development of a vacuum pump with a double-circuit lubrication system for milking machines

The efficiency of milking dairy farm animals depends on the reliability of the milking equipment. Domestic milking machines are equipped with UVU 45/60 with a rotary vacuum pump that has an extremely limited service life, which is mainly due to imperfection of the lubrication system for its working bodies. In addition, oil loss along with the exhaust air leads to high lubricant consumption and environmental pollution. Analysis of modern designs of foreign rotary vacuum pumps shows that their operational reliability and service life are increased at the expense of maximum reduction of friction in the working body due to the improvement of the lubrication system, increased productivity, and elimination of oil loss and environmental pollution. One of the technical solutions to solve these problems is to equip the vacuum installation with a device that provides circulating lubrication of the pump working bodies without emitting oil into the atmosphere. The team of authors substantiated the design of the oil trap for the pump lubrication system with the efficiency of separating oil from the exhaust air up to 95 %. Experimental vacuum installations with single-circuit and double-circuit lubrication systems have been developed. Production tests of vacuum installations performed at a number of farms in Stavropol Territory confirmed high efficiency of the proposed engineering solution. The operational reliability of the pump due to the circulating lubrication of its working bodies in terms of the prolonged overhaul period increased by 65-70 %. Irrecoverable oil losses and environmental pollution are almost excluded. The payback period for additional capital investments in the vacuum installation design does not exceed 1.2-1.5 years.

Modelling of inhomogeneous chamber states in rotary positive displacement vacuum pumps

Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are normally considered to be homogeneous. In this work it is shown, that the chamber state is inhomogeneous for rarefied gases due to the movement of the pistons which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. An efficient way to model these inhomogeneous states with a one-dimensional approach for geometrically abstracted chambers is shown. The approach is applied to chamber model simulations of a screw spindle vacuum pump (SSVP) and the results are compared to simulations with homogeneous chamber states and to measurements.

JUSTIFICATION OF CHANGE IN CASE OF VACUUM PUMPS

Milk production is closely related to the milking process. The operations that are involved in this process require high responsibility and are quite laborious. The economic efficiency of the milking process depends not only on the qualifications of the operators, but to a large extent is determined by the technical perfection of the means of mechanization that are used. After all, the vacuum pump, which is part of any milking installation, has a significant impact on the productivity of the latter. The operation of the executive elements of the milking machines, as well as the transportation of milked milk, depends on the amount of air taken. The perfect design of the vacuum pump affects the energy consumption of the milking process. The analysis of vacuum pumps used in the technological process of machine milking is made. Research and literary sources indicate that mechanical rotary vacuum pumps are most widely used, this is explained by a number of technical and economic indicators. The specific energy consumption of a rotary vane vacuum pump depends on the value of the set working vacuum and the rotor speed. In most rotary vane vacuum pumps, the housing design provides for the movement of air through the inlet pipe to the inlet port and does not fill the space between the two blades as much as possible. If the air is escaping, it cannot be quickly emitted through the outlet window. These disadvantages are eliminated by the fact that a transverse groove is located at the end (in the direction of movement of the rotor) of the inlet window. To effectively remove air from the pump, the outlet window, at the beginning (in the direction of the rotor movement), has a transverse groove, the dimensions of the grooves are 4/5 of the width of the vacuum pump housing and less than 1/2 of the width of the corresponding window. The proposed design of the body of the vacuum pump makes it possible to increase the productivity by 7-12% and reduce the power consumption for the drive by 8-10%, in addition, there is a decrease in the heating of the body to 67-74 °С.

Effect of Volume Fraction and Resin System on Tensile, Compression and Flexural Strength of Electrical Glass Fiber Reinforced Plastic Laminate

This work deals with the experimental studies on effect of changing volume fraction and also various resin systems like Epoxy LY556, AW106 & CY230 on ultimate tensile, compression and flexural strength of a polymer matrix composite. The specimens were prepared through vacuum assisted resin transfer molding technique. The vacuum pump is a double stage rotary vacuum pump of specifications 300 lpm, 1 hp &3ph. Reinforcements of different thickness/layer of bidirectional e-glass fibers were used and the epoxy resins of varying viscosities were used. The machining of the fabricated specimens was carried out using abrasive water jet cutting facility. The test coupons were tested as per ASTM standards. Tensile, compression and flexural tests were carried out for each experiment and three trials were made for each experiment in order to arrive at the average value of tensile, compressive and flexural strength. The inferences are drawn for each type of resin system and volume fraction of the matrix and reinforcement used which helps in understanding the enhancement in ultimate strength of the test coupon under study.

A study on the development of a numerical model for a rotary vane vacuum pump for brake boosters

A negative pressure is formed inside the brake booster in a running diesel vehicle by using a rotary vane vacuum pump. In vacuum pump design, it is important to reduce the time required to induce the minimum negative pressure required for immediate consecutive braking and to reduce the torque used to drive the pump. In this study, a numerical simulation model to predict the performance of a vacuum pump was developed and experimentally validated by comparing the pump’s drive torque and the time required by a 4 L chamber to reach the target pressure. The housing profile was obtained via 3D scanning, while the check valve, bypass hole, and groove, which significantly affect the pump performance, were mathematically described. The model was validated by comparing the vacuum chamber pressure variation and the average torque. Similarly, the pump performance with respect to changes in major design factors, such as check valve and bypass hole shapes, were compared against the experimental data. In addition, the pump performance was predicted as a function of the housing profile shape, which is difficult to evaluate experimentally, and a new profile shape to improve the performance was proposed.

Alumina reduction by laser ablation using a continuous-wave CO2 laser toward lunar resource utilization

Aiming at development of a new method of alumina reduction that is useful for ore mined from the moon, experiments of alumina reduction using CW laser ablation were conducted with a kW-class CW CO2 laser with 400–2000 W power. After a laser beam was focused on a sintered alumina rod, the surface was heated to a temperature necessary for ablation of alumina. Ambient pressure in the test chamber was controlled by supplying Ar gas at 0–0.30 atm, 0.50 atm and 1.0 atm initially, with gas evacuated using a rotary vacuum pump. Under those conditions, an ablation plume was ejected continuously from the sintered alumina rod surface, which was not observed in vacuum. Ambient pressure was increased to 0.40 atm, 0.65 atm, and 1.2 atm. Moreover, emission spectra from the ablation plume were measured; Al I line spectra were detected. Results show that alumina reduction occurred without reducing stores. The equilibrium temperature varied with ambient pressure and laser intensity: 3100–3700 K. Molar reduction of 9.7% and energy conversion efficiency of 0.64% were achieved. Further improvement of the molar reduction percentage can be achieved using increased laser intensity and ambient pressure.

Vakuumtechnologie für die chemische Verfahrenstechnik

SummaryVacuum technology for the chemical industry process engineering – New developments – established principlesVacuum technology in chemical process engineering has evolved constantly over the past decades. In the beginning, liquid ring vacuum pumps were used in almost all chemical processes. But this all changed in the 1960s with the introduction of the once‐through oil‐lubricated rotary vane vacuum pump. The development of the dry screw vacuum pump in the 1990s represented another milestone. These are the three main types of technology available to chemical engineers today. They therefore have the choice between the traditional but proven technology of the liquid ring vacuum pump, the once‐through oil‐lubricated rotary vane vacuum pump and the modern screw vacuum pump that requires no operating fluids whatsoever. The decision as to which type is the right choice should be left to a proven vacuum specialist. Each and every critical parameter – from the process conditions, process gases and integration into process control right through to assessing the economic efficiency, safety and reliability of the future vacuum generation – must be taken into consideration.

Study on the driving torque and target pressure time of a rotary vane pump for brake booster

Diesel cars use a rotary vane vacuum pump to create negative pressure inside the brake booster. In designing a vacuum pump, it is highly critical to reduce the time required to create enough negative pressure for applying brakes a second time and the torque required to drive the pump. Therefore, in this study, we set up test equipment to measure the driving torque and time to attain the target pressure of the rotary vane vacuum pump of a brake booster. In addition, the effects of the several design variables on these parameters were analyzed: The length and depth of grooves, thickness of an outlet check valve, and number of bypass holes. Optimal values of the design variables were proposed and verified to minimize the driving torque using the Taguchi method.

Carbon Thin Film on Silicon by Microwave Plasma

This work aims to develop a low pressure microwave plasma deposition system to coat carbon thin film on silicon substrate. The system use a commercial microwave oven as a microwave source to get plasma discharge. The vacuum pressure was achieved by two stage rotary vane vacuum pump which is capable to reach ultimate pressure at 2×10-1 Pa under borosilicate chamber glass. The carbon thin films was successfully deposited on silicon substrate by pure acetylene plasma with gas flow rate 30 ml/min at total operating pressure of -70 cmHg reading by analog dial vacuum gauge, using microwave power at 1,200 Watts and deposit time at 150 seconds. Raman analysis showed peak at around 1336.20 cm-1 (D-peak) and 1611.87 cm-1 (G-peak), by utilizing ID and IG can be determined that there are 43.22% of sp3 contained in deposited film. Energy Dispersive X-Ray analysis indicated that the deposited thin film compose of carbon atoms 82.00 at% and silicon atoms 18.00 at%. The morphology and the thickness of the film was investigated by scanning electron microscope and atomic force microscope, respectively.

Carbon Thin Film on Silicon by Acetylene DC Plasma Deposition System

This work aims to develop a low pressure DC plasma deposition system to coat carbon thin film on silicon substrate. The system use a parallel of grounding iron electrode and cathode copper electrode to ignite the plasma. The vacuum pressure was achieved by two stage rotary vane vacuum pump which is capable to reach ultimate pressure at 2×10-1 Pa under a glass chamber. The carbon thin films was deposited on silicon substrate by pure acetylene plasma with gas flow rate at 30 ml/min at total operating pressure of approximately at -70 cmHg reading by analog dial vacuum gauge. Energy Dispersive X-Ray spectroscopy was used to indicate the elements contained in the film. The morphology and the thickness of the film was investigated by scanning electron microscope. Raman analysis showed peak at around 1345 cm-1 (D-peak) and 1579 cm-1 (G-peak), by utilizing ID and IG can be evaluated that there are 46.45% of sp3 contained in deposited film.

Improved Isolation of Microbiologically Produced (2R,3S)-Isocitric Acid by Adsorption on Activated Carbon and Recovery with Methanol

A new, efficient method for the isolation of (2R,3S)-isocitric acid (ICA) from its fermentation solution was developed. It is noteworthy that this method is based on selective adsorption directly from the fermentation solution on activated carbon, followed by the release of both ICA and citric acid by means of elution with methanol and their final separation by known methods. Thereby, several disadvantages were overcome: Electrodialysis is no longer necessary to remove cations such as Na+ from the fermentation solution. Also, several hitherto accompanying dyestuffs were not observed with this method. Furthermore, removal of water by distillation is expendable. Eventually, the new crude product is of a quality that also avoids the use of a tedious slide vane rotary vacuum pump distillation of the trimethyl esters of both acids, which hitherto was the basis for the separation of ICA. In summary, the new method distinctly spares energy as well as time.

Measurement of outgassing rate for GTAW welded SS304 materials

Outgassing plays an important role to achieve Ultra High Vacuum (UHV) and to maintaining the required vacuum level of the vessel. For a large size machines like Tokamak, accelerators, space simulation chambers, outgassing from the structural materials and their welding sections need to be checked during the design. Hence studies were carried out for the measurement of outgassing rate for the Gas Tungsten Arc Welding (GTAW) welded SS304 materials at OutGassing Measurement System (OGMS) at IPR Extension Lab. The system consists of two chambers, pumping chamber and sample chamber, made up of 304 grades Stainless Steel pre-air baked at 400 °C. The pumping chamber connected to a turbo molecular pump having pumping speed 240 l/s, backed by a rotary vacuum pump having pumping speed 5m3/hour. Pumping chamber and sample chamber connected through a 100 CF flange having a circular aperture of 5.2 mm diameter. The conductance of aperture is 2.47 l/s. Bare SS304 sample & GTAW welded SS304 samples are prepared with 100mmX50mmX5mm and 95mmX55mmX5mm dimensions respectively. The base outgassing rate of the blank system is 2.34×10-11 mbar l/s-cm2. The calculated outgassing rate is 3.66×10-10 & 4.37×10-10 mbar l/s-cm2 for bare sample & welded sample. From the partial pressure analysis it has been found that hydrogen and nitrogen are in the partial level of 3.35×10-9 & 2.36×10-9 for bare sample and 3.14×10-9 mbar & 2.33×10-9 mbar for welded sample. It has been observed that, the GTAW doesn't have major effect on outgassing rate and one can use welded joint for designing a large vessel welding sections.

Vacuum Desiccator as a Simple, Robust, and Inexpensive NMR Tube Cleaner

A simple, robust, and inexpensive apparatus for cleaning several NMR tubes is easily fit up and used from readily available glassware, including a beaker, a desiccator, and a rotary evaporator vacuum pump.

揺動ピストン形油回転真空ポンプの省エネルギー化

A rotary plunger vacuum pump has high displacement efficiency and robust structure. The pumps are used in hard process of general industry. The demand of saving energy in industry is increasing these days. Rotary plunger vacuum pumps are required to suppress the energy as well. Therefore, the approach of the energy reduction for the pumps has begun. The pump's power consumption could be explained by two factors. One is the mechanical loss and the other is the compression work. We developed a rotary plunger vacuum pump which implement low frictional structure. The low frictional structure allowed low viscosity vacuum oil. With efficient driving by controlling rotation speed, this pump reduced energy by 30% compared to the conventional pump. Beyond that we introduced the way of energy saving by reduction of the compression work.