A diaphragm pump is a type of volumetric pump that has excellent sealing performance. An electromagnetic diaphragm pump is a kind of widely adopted diaphragm pump that has a simple structure, low ...power loss, and high cost performance. However, the calculation method of deformation for the electromagnetic diaphragm pump rubber diaphragm is presently lacking. Herein, a calculating method of deformation for the electromagnetic diaphragm pump rubber diaphragm is proposed. By establishing and analyzing a deformation model of the electromagnetic diaphragm pump rubber diaphragm, a theoretical relationship between the deformation of the electromagnetic diaphragm pump rubber diaphragm, the size of the electromagnetic diaphragm pump rubber diaphragm and the pressure of fluid is determined. The experimental results indicate that the biggest difference between the tested axial deformation and the calculated axial deformation of the electromagnetic diaphragm pump rubber diaphragm is 0.04 mm and the calculation results show agreement with the experimental results.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Using water-glycol hydraulic fluid as a working medium is an important development direction in deep-sea hydraulic systems. Viscosity is an important parameter in the characterization of flow fields. ...The study of the viscosity characteristics of polyalkylene glycols as a water–glycol thickener in deep-sea environments can help to research the viscosity properties of water glycol hydraulic fluid under deep-sea conditions. In this paper, a molecular dynamics method is used to compute the kinematic viscosity of PAG 75-W-130 based on the OPLS-AA force field. Dynamic viscosity was calculated by the nonequilibrium molecular dynamics method. At ambient pressure and temperatures from 293.15 to 373.15 K, the calculated density is in accord with the experimental results and the calculated viscosity is more than the experimental result. Moreover, the density and dynamic viscosity of PAG 75-W-130 are predicted in a deep-sea environment. The calculated viscosity and density increase exponentially with increasing pressure. The density increases from 1069.2 to 1110.4 kg/m3 at full sea depths, and the viscosity is up to 10.99 Pa·s at the sea depth of 11,000 m.
The influence of high hydrostatic pressure on tribological characteristics of carbon fiber reinforced Poly-ether-ether-ketone (CF/PEEK) against 431 stainless steel (431SS) was investigated. ...Hydrostatic pressure ranged from normal pressure to 80 MPa at a step of 20 MPa to simulate the environmental pressure of the deep ocean. The results suggest that the average friction coefficient decreases with increased hydrostatic pressure. Hydrostatic pressure helps reduce the wear rates of CF/PEEK and 431SS. As the pressure increases, the main wear and friction mechanism of CF/PEEK changes from adhesive wear to fatigue wear, while the main wear mechanism of 431SS is abrasive wear. Compared with the sliding surface after normal pressure experiments, the surface roughness Ra of CF/PEEK will be smaller after high pressure experiments. The crystallinity of CF/PEEK decreases linearly with hydrostatic pressure, indicating a possible decline in mechanical properties. Moreover, comprehensive results suggest that this friction pair can be used under the hydrostatic pressure up to 80 MPa.
Display omitted
•Hydrostatic pressure ranges from normal pressure to 80 MPa at a step of 20 MPa.•Increased hydrostatic pressure helps reduce the friction coefficient and the wear rates of CF/PEEK and 431SS.•As the pressure increases, the main wear and friction mechanism of CF/PEEK changes from adhesive wear to fatigue wear.•The main wear mechanism of 431SS is abrasive wear.•The crystallinity of CF/PEEK decreases almost linearly with hydrostatic pressure.
Electromagnetic diaphragm pump is a kind of widely applied diaphragm pump that has promising sealing performance, simple structure and low power loss. Planar pole electromagnet is a significant ...component of the electromagnetic diaphragm pump. However, the sharply changing displacement-force characteristics of the planar pole electromagnet do not match the constant load characteristics of the electromagnetic diaphragm pump. Herein, an electromagnet with variable pole area is put forward. A theoretical relationship between structural parameters, the Ampere turns and the electromagnetic force of the electromagnet with variable pole area is determined by analyzing the equivalent magnetic circuit of the electromagnet with variable pole area. The experimental results imply that the initial electromagnetic force of the electromagnet with variable pole area is 32.51% larger than the planar pole electromagnet, the engaging electromagnetic force of the electromagnet with variable pole area is 22.3% smaller than the planar pole electromagnet and the displacement-force characteristics of the electromagnet with variable pole area match the constant load characteristics of the electromagnetic diaphragm pump.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Open-circle sea water hydraulics, utilizing surrounding water as a working medium, has become more and more popular in submersible. Axial piston pump with port valves is used frequently in the ...open-circle water hydraulic system. Port valve is one of the important parts in this type pump. However, there are few literatures about the effect of the port valves’ materials on the noise characteristic of the water pump. In this study, the effect of materials on the noise of the pump was researched through experimental and theory simulation methods. The influences of three kinds of plastics (Polyetheretherketone (PEEK), Polytetrafluoroethylene (PTFE), Aliphatic polyamides (NYLON)) and one kind of anti-corrosion stainless steel (316L) are compared. The noise of the pump with the different materials port valve seat ranges from high to low as the order: 316L>NYLON>PEEK>PTFE. The differences would contribute to the collision between valve spool and seat, which is identified by the simulating results. The experimental results showed that the difference of noise between PEEK and PTFE is small. In addition, the lifespan and volumetric efficiency are also taken into considering. The PEEK is selected to use in the seawater pump for a large submersible.
•Port valve is one of the important parts of piston pump.•Effect of materials on the noise of the pump was studied.•Noise of the pump ranges from high to low as the order: 316L>NYLON>PEEK>PTFE.•Life span and volumetric efficiency are also taken into considering.•The PEEK is selected to use in the seawater pump for a submersible.
Miniature multi-stage reciprocating compressor is the core component in the on-board continuous high-pressure gas supply system. Intercoolers play an important role in determining the thermodynamic ...performance of multi-stage reciprocating compressor. However, adequate inter-stage volume cannot be provided to miniature multi-stage reciprocating compressor due to the restriction of compacted dimension. Understanding the thermodynamic performance with insufficient inter-stage volume is the key issue for design and application of miniature multi-stage reciprocating compressor. However, the previous work focused on the thermodynamic process in single-stage cylinder, the proposed model cannot predict the real-time thermodynamic process in intercoolers. In this paper, stage-in-series thermodynamic model has been established by connecting the multi-stage cylinders through the intercoolers and the internal transient heat transfer was emphasized. The in-cylinder and in-intercooler thermodynamic properties have been numerically analyzed under insufficient inter-stage volumes. Experimental investigation on compressor performance has been carried out by varying the intercooler channel diameter. The results show that insufficient inter-stage volumes bring about the abnormal movement of suction and discharge valves. Pressure peak in former-stage cylinders increases when the inter-stage volume decreases, which results in obvious increase in frictional loss and power consumption. This study provides significant references for design optimization of miniature multi-stage reciprocating compressor. Furthermore, the proposed methods can be applied to large-scale reciprocating compressor for improving efficiency and reducing power consumption.
•The cover area and droplet size of nozzles increase with spray cone angle.•Extinguishing time increases with spray cone angle, and decreases with flow rate and supply pressure.•More time exceeding a ...certain value for water mist discharge duration is not helpful to the cooling.•Gas concentrations are not affected by the water mist discharge duration if it exceeds the extinguishing time.•The flow rate and spray cone angle should match mutually, in order to maximize the utilization of water.
Water mist is an ideal way in enclosed spaces, where fire suppression efficiency is very important due to limited water and water damage to equipment. The purpose of this paper is to find a more effective way of fire suppression performance by changing characteristics of nozzles, taking into account extinguishing time, water consumption, toxic gas concentration, temperature decay and cover area. Two groups of pressure-swirl nozzles with the same flow rate and different spray cone angles were employed. The angle was adjusted by changing diameters and lengths of entrance, swirl chamber and orifice of nozzle. It was found that the cover area and the droplet size increased slightly with the spray angle. The fire tests results showed that the extinguishing time increased with the spray cone angle, and increased with the flow rate and the operating pressure decreasing. The temperature decay rate was improved by decreasing the angle or increasing the flow rate. In addition, with an increase in the extinguishing time, the concentration of O2 decreased while the CO and CO2 increased. However, the gas concentrations were not affected by the water mist discharge duration if it exceeded the extinguishing time. For a specific region and a certain amount of water, the performance can be improved by the approach: increasing the flow rate and the spray angle simultaneously and decreasing the discharge duration. The authors suggest setting proper flow rate and spray cone angle which match mutually, in order to maximize the utilization of water.
The potential energy recovery of hydraulic excavators is very significant for improving energy efficiency and reducing pollutant emissions. However, the more common solutions for potential energy ...recovery require more energy conversion processes before these potential energies can be reused, which adds to the complexity and high cost of the system. To tackle the above challenges, we proposed a novel energy recovery system for hydraulic hybrid excavators based on the digital pump with an energy recovery function. The new system could operate in three different modes: pump, energy recovery, and direct reuse. Based on the descriptions of the working principle of the digital pump and the whole energy recovery system, the mathematical models of the digital pump, the excavator arm cylinder, and the accumulator were established and the AMESim simulation model (combining mechanics, hydraulics, and electrics) was developed. The dynamic characteristics of the energy recovery system were studied under no-load and full-load conditions. The simulation results showed that this scheme could achieve 86% energy recovery when the boom was lowered and reused the recovered energy directly when raised, which could decrease the system input energy by 78.1%. This paper can provide an optimized solution for construction machinery or off-road vehicles and presents a reference for the research on digital hydraulics.
Considering the deformation of a designed seawater direct-acting relief valve (SDARV) in deep-sea environment, which has a significant influence on the dynamic performance, the mathematic model of ...SDARV was established and related dynamic characteristic simulations were conducted. Since the fit clearance between damping spindle and damping bush is the key parameter affecting the dynamic characteristic of SDARV, the different fit clearances against varying depths were studied by ANSYS Workbench. The variations of seawater properties at different sea depths were also introduced to investigate the effect. From this study, the valve's dynamic performance after optimization in deep-sea environment was researched by MATLAB and the effective sea depth suiting for normal work was got. The results indicated effective dynamic performance of the SDARV within the depth of 1700m and the optimum fit clearances after deformation should be kept in the range of 0.019mm to 0.045mm in deep sea environment.
•A direct-acting relief valve using seawater as working medium was proposed.•The mathematical model of the seawater relief valve was established.•The deformation of the damping bush in deep-sea environment has been studied.•The seawater relief valve shows reliable dynamic performance within the depth of 1700m.•The optimum fit clearances after deformation are in the range of 0.018mm to 0.041mm in deep sea environment.
In this paper, an alternative method to predict the noise of a submersible Axial Piston Pump (APP) for different valve seat materials is presented. The proposed method is composed of an Artificial ...Neural Network (ANN) model trained using experimental data and integrated with a hybrid algorithm consists of Cat Swarm Optimization (CSO) and Firefly Algorithm (FA) algorithms. The hybrid CSFA algorithm is used as a subroutine in the ANN model to estimate the ANN weights. The FA is used as local operator to improve the exploitation ability of CSO. The obtained results prove the excellence of the proposed method in predicting the noise of APP considering four different valve seat materials (Polytetrafluoroethylene (PTFE), Polyetheretherketone (PEEK), Aliphatic polyamides (NYLON), and stainless steel (316 L)), five speed levels, and six system pressures. Moreover, the effects of different mechanical properties of the valve seat materials as well as operating conditions (speed and system pressure) have been investigated.
PDF
