Vacuum Valve Research Articles

An Experimental Investigation of the Material Properties of the A356 Aluminum Alloy Power Fittings in the Vacuum Die-Casting Process.

To enhance the performance of ultra-high voltage power fittings in severe weather conditions without altering their current structure, the high-strength and toughness aluminum alloys were rationally selected to study the optimization of the die-casting process. This approach aims to improve the overall longevity and function of the power fittings in extreme climates. First of all, the propose of this study is to use the material's strength-toughness product (STP) concept to evaluate the material stability of the power fitting impact resistance and fatigue toughness in order to determine the appropriate material selection. Secondly, the location of the mold's sprue and gate was optimized through finite element simulation to prevent gas volume and flow defects during the casting process. This improves the material's toughness and anti-fatigue failure characteristics of the product. Then, vacuum equipment and a vacuum valve auxiliary system were added based on the existing die-casting machine, and the mold structure was optimized to enable the vacuum die-casting process. Finally, a water-based boron nitride environmentally friendly mold release agent was used to solve demolding difficulties with an A356 aluminum alloy and improve mold lubrication and surface quality. The production of quad-bundled spacers using A356 and vacuum die casting has resulted in parts with a tensile strength of at least 250 MPa and an elongation of no less than 7%. This improvement has laid a foundation for enhancing the operational reliability of existing overhead transmission line fittings.

Cryogenic vacuum valve with actuation times down to 50 ms.

We have conceived, built, and operated a cryogenic vacuum valve with opening and closing times as short as 50ms that can be used in strong magnetic fields and across a broad range of duty cycles. It is used to seal a cryogenic Penning trap at liquid-helium temperature for long-term storage of highly charged ions in a vacuum better than 10-15 hPa from a room-temperature ion beamline at vacuum conditions around 10-9 hPa. It will significantly improve any experiment where a volume at the most extreme vacuum conditions must be temporarily connected to a less demanding vacuum during repeated experimental cycles. We describe the design of this valve and show measurements that characterize its main features.

Vacuum Valve as a Hydrodynamic Object

Vacuum Valve as a Hydrodynamic Object

Two states of liquid water with a qualitative difference in behavior of saturated vapor pressure

A new analysis method of the liquid water state based on testing of saturated water vapor extracted from the surface of the liquid phase is proposed. The method uses transport properties of water vapor flow when water vapor passes through a vacuum valve. The method allows you to divide the states of liquid water samples into rest or restless ones. Restless water is obtained from rest water by mechanical influence on it, for example, vibration or mixing. The return time of restless water to a rest state was estimated based on experimental data.

The Application of Vacuum Valve Technology as AFR Settings in 3500 Watt Electric Generator Operated by Methane Gas

The scarcity of fuel oil, especially the gasoline type, is now a national problem that needs to be solved. This is caused by the rapid growth of industry and transportation. On the other hand, the problem of handling wet garbage has not been maximal, causing pollution that can disrupt health. The impact of this problem is felt also in the use of household-scale generators that operate using gasoline fuel. This study aims to convert gasoline to methane gas in the operation of a 3500 Watt Generator (Electric Generator Set). Methane gas (CH4) is obtained from the gasification process of wet waste. The method used for the AFR (Air-Fuel Ratio) regulator is the use of vacuum valve components. The use of this method cannot be separated from the easy aspects of the maintenance/repair, easy to make and cheap price. The target to be achieved in this research is to get performance data of generators operated with Methane gas fuel. The generator which is used as a research object is a generator household scale with a maximum power of 3500 Watt. Results variables to be observed among other: engine efficiency as well as optimum engine AFR generator. Furthermore, the data is compared with the data generated generator that uses gasoline fuel. This research is an experimental study, starting with the design of the vacuum valve component, followed by the installation of the component on the generator machine and ending with a machine test. The experimental data on the generator with the nominal power of 3500 Watt is: Operated by Gasoline, the optimum power, Popt is 3750 Watt, Max. efficiency, ηmax is 62.2%; AFRopt is 6.7, then operated by methane gas, optimum. power, Popt is 3270 Watt, Max efficiency, ηmax is 66,1%, AFRopt is 7,2. So, gas methane can be used to replace gasoline to operate 3500 Watt generator.

Characterization of a Newly Designed Vacuum Valve Having a Variable Conductance Function

A valve has a function of controlling the flow of a fluid by opening or closing a passage. A valve can thus be used to create different pressures for the two areas on either side of the valve. However, the conventional vacuum valve has a problem that the flow rate of the gas cannot be controlled. In this light, it is necessary to develop a vacuum valve that is capable of precisely controlling the flow rate of the gas without leakage of the gas. Recently, we developed a variable conductance vacuum valve to control the inlet pressure for the vacuum chamber. The variable conductance valve developed in this study uses a similar iris structure to that of conventional control valves employed in normal water and sewage pipes, but the valve has no outer mounting hole or fastening holes for coupling the driving parts because the iris structure is changed in a non-contact manner by a magnetic field. Therefore, the valve in this study has the advantage that the fluid leakage of the valve can be completely blocked without a separate device such as packing or sealing components or an O-ring, and therefore, the internal vacuum state can be maintained. The fabricated valve showed a relative repeatability error within 0.5% and a relative reproducibility error within 5%. These results demonstrate that the conductance variable valve developed in this study is suitable for easily changing the pressure inside a vacuum chamber by adjusting the conductance.

Dynamic Modeling and Simulation of the Fuel Delivery Process Under Time-Varying Tokamak Fuel Demand

This paper presents a dynamic model and simulation of the fuel delivery process between the separation system and the fueling system in the fusion fuel cycle considering the time-varying tokamak fuel demand. The fuel delivery process consists of vacuum pumps, valves, pressure vessels, and pipelines. Experimental data are applied to model the performance curves of the vacuum pumps. The delivery pressure is needed to be controlled to satisfy the pressure requirement of the fueling system. The developed dynamic model can be used to investigate delivery pressure fluctuation under various demand scenarios including a certain peak demand. The model is applied to the tritium delivery line during the inductive operation of the tokamak. Several rules for vessel switching are analyzed to examine the change of delivery pressure. The results show that the fluctuation can be reduced by switching vessels just before peak demand. The pressure fluctuation must be avoided by improving the flow coefficient of the control valve.

Experimental study of an Adsorption Refrigeration Test Unit

Adsorption refrigeration has been considered as an important way to utilize low-grade thermal energy efficiently. To overcome the drawbacks of low coefficient of performance (COP) and specific cooling power (SCP), a novel adsorption refrigeration test unit is proposed. The experimental research has been carried out from the view of heat and mass performance enhancement of adsorber and modification of the system structure. The AQSOA coated heat exchanger supplied by Mitsubishi Plastics Inc. is employed as adsorber and the test unit is designed without vacuum valve and with a double-layers evaporator. It is indicated that the COP, SCP and volume cooling power density (SCPv) can reach 0.37, 410.625 W/kg and 43 kW/kg, respectively, under the conditions of 90°C hot water temperature, 35°C cooling water temperature, 11°C chilled water temperature and 480 s optimal half cycle time. What is more, the effects of operating parameters, such as hot water temperature, cooling water temperature, chilled water temperature and structural form of the evaporator, on the adsorption performance are investigated in detail. It is demonstrated that it is feasible to utilize various low grade heat thermal energy.

A zeolite 13X/magnesium sulfate–water sorption thermal energy storage device for domestic heating

A sorption thermal energy storage (TES) device for domestic heating is presented in this article. The TES device adopts the new design scenario with valve-less adsorber and separate reservoir to eliminate the large-diameter vacuum valve for vapor flow, which decreases the cost, reduces the vapor flow resistance, and improves the system reliability. The device is charged by electric heater, which can add much flexibility to the building energy system as well as contribute to the valley filling and peak shaving from the demand side management. The newly developed composite sorbent of zeolite 13X/MgSO4/ENG-TSA (expanded natural graphite treated with sulfuric acid) with the salt mass fraction of 15% in the zeolite 13X/MgSO4 mixture is tested and used in the TES device (denoted as XM15/ENG-TSA). Experimental results show that the TES device with XM15/ENG-TSA has the energy storage density of 120.3 kWh m−3 at 250 °C charging temperature and 25–90 °C discharging temperature. The temperature lift is as high as 65–69 °C under the adsorption and evaporating temperatures of 25 °C. The impregnated MgSO4 dramatically improves the temperature rising rate during the adsorption heat recovery process, but the specific energy storage capacity of XM15/ENG-TSA is similar to that of zeolite 13X/ENG-TSA. The effect of the impregnated MgSO4 suggests that MgSO4 can be used for low-temperature TES to relieve the self-hindrance of the hydration reaction.

Study on the performance of compact adsorption chiller with vapor valves

Adsorption refrigeration is considered a green refrigeration technology that can be driven by a low-grade heat source to generate cooling power. However, the large bulk of adsorption chillers can limit its use especially automobiles. The size of the adsorption chiller is a very important consideration for applying in the automobile. The new type of compact adsorption chiller applied in the automobile was proposed corresponding with the specification of the automobile installation, and was about 40L by volume in this paper. A vacuum valve was used to increase the adsorption chiller size considerably. Thus, the new adsorption chiller has four pieces of vapor valves instead of vacuum valves, as well as two pieces of adsorbers, an evaporator, and a condenser. The vapor valve was controlled by the pressure difference at both sides. The prototype adsorption chiller was manufactured and evaluated for its cooling power and coefficient of performance by testing the inlet and outlet temperatures of the evaporator, flow rate of chilled water, and cycled time. The maximum cooling power was approximately 1.5kW at a driving temperature of 368K and a cycle time of 90s.

Comparison of permeation of atmospheric gases through Viton O-ring gaskets for different initial conditions

Viton O-ring gaskets are frequently used in high vacuum for demountable flange and vacuum valve seals. Atmospheric gases, particularly water vapor from humid air, permeate through Viton gaskets and thus limit the lowest attainable pressure level in vacuum systems. In this work, a comparison of a vacuum degassed Viton O-ring gasket and a gasket fully saturated with atmospheric gases was performed. A reference measurement with an alternative soft metal gasket for Klein Flange type flanges was also made. The permeation rate of each individual gas from the atmosphere (water vapor, N2, O2, Ar, and CO2) through the Viton O-ring was measured using quadrupole mass spectrometry. The partial gas flow curves Q(t) were also modeled using finite difference modeling (FDM). Using FDM, one can determine the diffusion constant, permeability, and solubility of the gas in the material.

Remote-Steering Antennas for 140 GHz Electron Cyclotron Heating of the Stellarator W7-X

For electron cyclotron resonance heating of the stellarator W7-X at IPP Greifswald, a 140 GHz/10 MW cw millimeter wave system has been built. Two out of 12 launchers will employ a remote-steering design. This paper describes the overall design of the two launchers, and design issues like input coupling structures, manufacturing of corrugated waveguides, optimization of the steering range, integration of vacuum windows, mitrebends and vacuum valves into the launchers, as well as low power tests of the finished waveguides.

Water Column Separation and Cavity Collapse for Pipelines Protected with Air Vacuum Valves: Understanding the Essential Wave Processes

AbstractElevated high points along a pipeline profile are the most common places where air vacuum valves (AVVs) are installed. This paper uses basic water hammer theory to semianalytically explore the effects of such AVVs. A simple frictionless reservoir-pipe-reservoir system with an exaggerated intermediate high point is considered with a sudden flow curtailment assumed upstream. Key design parameters such as the maximum air pocket volume, the duration of air pocket growth and collapse, and the maximum magnitude of the pressure spike resulting from water column rejoinder are semianalytically developed for various high point locations. The magnitude of the reduced pressure wave created by the refraction at the high point, and both its vertical and horizontal position, are demonstrated to crucially determine system performance. Numerical examples are compared with the semianalytical expressions to highlight the accuracy of the derived expressions. The effect of friction is later introduced to help reveal f...

Experimental Studies, Geometry Acquisition and Grid Generation Of Diesel Engine Inlet Port For Three Dimensional Calibrated Cfd Code For Futuristic Design

A typical diesel engine port is of complicated geometry . This paper addresses the experimental studies of intake port of a four cylinder diesel engine for different vacuum pressures and valve lift positions. In this study the cylinder head is experimented through a paddle wheel flow setup which gives the flow coefficient and swirl number as output. The main scope of the work is to understand the flow behaviour through the intake port and finally to determine mean flow coefficient and mean swirl number for different valve lift ratios L/D, where L is valve lift and D is bore diameter. This paper also addresses the geometry acquisition and grid generation for three dimensional Computational Fluid Analysis for flow filed computation and obtain a calibrated CFD code for future design once the code is validated with experimental results

Comparative evaluation of vacuum sewer and gravity sewer systems

Two most common types of sewer systems are gravity sewer system and pressure sewer system. In last 25 years, a relatively new wastewater collection system called vacuum system got acceptance and popularity in certain circumstances (e.g., hilly and rocky terrains, areas with high groundwater table, unstable soil condition). Due to lack of comprehensive understanding and design procedure, very limited studies on vacuum sewer have been reported in the literature. This study complied a complete design procedure for vacuum system and attempted to compare and evaluate capital and operating costs of the vacuum sewer system against gravity counterpart. From the detailed designs of two systems for same areas, the vacuum system found relatively cheaper in terms of total construction and operation costs. The excavation cost for vacuum system is around one-fourth of the excavation cost for the gravity system. However, total manhole cost in gravity system is relatively cheaper (33 %) than the total cost of the similar components in vacuum system (inspecting valves, vacuum valves, division valves and connections). Other costs, like trench filling materials cost, labor cost, dewatering and safety measure costs are also less in vacuum system compared to the similar costs for the gravity system. Total energy cost for vacuum system is around 6.5 % less compared to the total energy cost for the gravity counterpart for same time period. Overall, vacuum system is around 30 % less expensive than gravity system.

Development of a control system for compression and expansion cycles of critical valve for high vacuum systems

A control system with feedback loop is designed, developed and tested to monitor the life cycles of the axial valve and bellows used in vacuum valves. The control system monitors number of compression cycles of any bellow or closing and opening cycle of a valve. It also interfaces vacuum gauges or pressure gauges to get pressure values inside the system. To find life cycle of valve, the developed control and monitoring system is integrated with an axial valve experimental test set up. In this system, feedback from the vacuum gauge attached to valve enclosure, is given and the life cycle test is automated. This paper describes the control and monitoring system in details and briefs the experiment carried out for valve life cycle. The same system can be used for life cycle estimate for bellows. A suitable GUI is also developed to control the function of the components and resister the number of cycles.

Experimental Studies on the Intake Port of a Diesel Engine to Determine Swirl

This paper focuses on experimentalstudies of intake port of a four cylinder diesel engine for different vacuum pressures and valve lift positions. In this study, the cylinder head is experimented through a paddle wheel flow setup, which gives the flow coefficient and swirl number asoutput. Main scope of the work is to understand the flow behaviour through the intake port and finally to determine mean flow coefficient and mean swirl number for different valve lift ratios L/D, where L is valve lift and D is bore diameter.

Electromagnetic Wave Excitation, Propagation, and Absorption in High Current Storage Rings

We analyze a variety of electromagnetic effects in storage rings with extremely high currents. Specifically, we discuss our experience in the operation of the PEP-II (SLAC B-factory). We present some outstanding and sometimes unpredictable effects of the behavior of electromagnetic waves excited by intense beams inside a vacuum chamber in storage rings. Although the impedance of the rings is usually designed to be small, intense high-current beams can still generate significant microwave power. This power can be enough to damage vacuum beam chamber elements, which may absorb electromagnetic waves. The most sensitive elements are RF seals, vacuum valves, shielded bellows, beam position monitor buttons, and ceramic tiles. Additionally, microwave heating leads to vacuum pressure spikes or even vacuum pressure instabilities that brings high detector background. Resonance excitation of the electromagnetic field may lead to a very high electric component amplitude that can cause breakdowns leading to sparks and discharges. Finally, high-power electromagnetic waves can be responsible for beam instabilities in the ring. Proper absorption of these generated waves may eliminate these effects. We feel our experience will be helpful in the design of new high current synchrotron light sources and storage rings.

Demonstrating Functional Equivalence of Pilot and Production Scale Freeze-Drying of BCG.

Process analytical technology (PAT)-tools were used to monitor freeze-drying of Bacille Calmette-Guérin (BCG) at pilot and production scale. Among the evaluated PAT-tools, there is the novel use of the vacuum valve open/close frequency for determining the endpoint of primary drying at production scale. The duration of primary drying, the BCG survival rate, and the residual moisture content (RMC) were evaluated using two different freeze-drying protocols and were found to be independent of the freeze-dryer scale evidencing functional equivalence. The absence of an effect of the freeze-dryer scale on the process underlines the feasibility of the pilot scale freeze-dryer for further BCG freeze-drying process optimization which may be carried out using a medium without BCG.

Design and experimental study of a silica gel-water adsorption chiller with modular adsorbers

A silica gel-water adsorption chiller driven by low-grade heat is developed. System configuration without any vacuum valves includes two sorption chambers, a 4-valve hot/cooling water coupled circuit and a 4-valve chilled water circuit. Each sorption chamber is composed of one adsorber, one condenser and one evaporator. The design of this chiller, especially the design of modular adsorber, is suitable for low-cost industrial production. Efficient and reliable heat and mass recovery processes are also adopted. This chiller is tested under different conditions and it features the periodic variations of temperatures and cooling power. Through the experimental study, the optimal cooling time, mass recovery time and heat recovery time are 720 s, 40 s and 24 s, respectively. Besides, the obtained cooling power, COP and SCP are 42.8 kW, 0.51 and 125.0 W kg−1, respectively, under typical conditions of 86/30/11 °C hot water inlet/cooling water inlet/chilled water outlet temperatures, respectively.