Single-piston Pump Research Articles

Fluid dynamic analysis of a cryogenic piston pump

Cryogenic piston pumps are commonly found in cryogenic systems to pressurize low-temperature liquefied fuels, such as liquified natural gas (LNG) or hydrogen, which are then gasified and stored in high-pressure vessels. The main challenges to be tackled in the design of these machines concern the low operating temperatures, high discharge pressures, and especially the need to avoid liquid evaporation, as this can lead to a reduction of volumetric efficiency or even to the shutdown of the pump. Two effects can cause the formation of vapor bubbles: cavitation, i.e., when the static pressure falls below the saturation value during the suction phase, and evaporation due to a temperature increase of the cryogenic liquid.In this study, a numerical analysis of a cryogenic single-piston pump is carried out. In the first part of the activity, the suction phase is studied through three-dimensional, steady-state CFD simulations. The performance of the pump in terms of pressure losses is evaluated and possible improvements to the suction geometry are identified.Then, two-phase steady-state Eulerian-Eulerian simulations are performed. The Rayleigh-Plesset model is used in order to evaluate the onset of cavitation. The minimum inlet pressure conditions that avoid cavitation are identified for two different geometries underlining the positive effect of the introduced modifications. Results show that the methodology applied in this work can lead to improvements in cryogenic pump design, reducing the static pressure losses and hence limiting the risk of cavitation.

Distribution parameter modeling and experimental verification of constant-pressure variable displacement pump

To provide a precise model of dynamic components in the constant pressure pump, and to improve the accuracy of dynamic calculation of the constant-pressure hydraulic system in its design stage, the research undertook mapping on a particular constant pressure pump and determined its basic structural parameters. Then, with the AMESim software, the research adopted separate structures from the level of basic components to establish the model of single-piston pump, the model of variable displacement pump, and the model of adjustable mechanism for the swashplate, respectively. The three models were combined with the constant-pressure variable displacement pump before it was encapsulated in a super component. By controlling the flow discharge of the constant pressure pump, and by switching on and off the constant pressure valve with the internal and long-distance pressure control, the research undertook the simulative test and the corresponding experimental test on the characteristics of pressure response of the constant pressure pump. The results of both tests agreed well with each other. Thus, it verifies the precision of the established constant pressure pump model in performing accurately in response design and analytical calculation.

3D-CFD Simulation of Confined Cross-Flow Injection Process Using Single Piston Pump

Injection process into a confined cross flow is quite important for many applications including chemical engineering and water desalination technology. The aim of this study is to investigate the performance of the injection process into a confined cross-flow of a round pipe using a single piston injection pump. A computational fluid dynamics (CFD) analysis has been carried out to investigate the effect of the locations of the maximum velocity and minimum pressure on the confined cross-flow process. The jet trajectory is analyzed and related to the injection pump shaft angle of rotation during the injection duty cycle by focusing on the maximum instant injection flow of the piston action. Results indicate a low effect of the jet trajectory within the range related to the injection pump operational conditions. Constant cross-flow was used and injection flow is altered to vary the jet to line flow ratio (QR). The maximum jet trajectory exhibits low penetration inside the cross-flow. The results showed three regions of the flow ratio effect zones with different behaviors. Results also showed that getting closer to the injection port causes a significant decrease on the locations of the maximum velocity and minimum pressure.

3D-CFD Simulation of Confined Cross-Flow Injection Process Using Single Piston Pump

3D-CFD Simulation of Confined Cross-Flow Injection Process Using Single Piston Pump

Mechanical design and modeling of a single-piston pump for the novel power take-off system of a wave energy converter

A multi-pump, multi-piston power take-off wave energy converter (MP2PTO WEC) has been proposed for use with a novel renewable energy harvester termed the Ocean Grazer. The MP2PTO WEC utilizes wave motion to pump–via buoys connected to pistons–working fluid within a closed circuit and store it as potential energy that can be converted to electricity via turbines. This paper introduces the mechanical design and model-based performance prediction of a single-piston pump that constitutes the basic building block for the MP2PTO WEC. Results provide preliminary validation of aqueous lubrication as a viable means of reducing friction and wear, suggesting that water-based hydraulic fluids can prohibit solid contact at the piston-cylinder interface while reducing volumetric leakage, and allowing for an estimation of the energy extraction efficiency for the mechanical pumping system. Pending more thorough and extended tribological investigations using the methodology introduced in this paper, findings suggest that the overall system efficiency will be dictated by the hydrodynamics of the buoys actuating the pumping system.

가변 사판식 피스톤펌프의 맥동 변수 분석 및 최적 밸브플레이트 노치 설계를 위한 압력 및 유량맥동에 관한 연구

We propose a simulation technique to estimate the reduction effect of the pressure/flow pulsation by analysis of the pulsation variables and notch shape of the valve plate of a swash-plate-type variable piston pump. First, using SimulationX, we perform a theoretical kinematic analysis according to the variable swash-plate angle and rotational velocity in order to design a single-piston pump. In designing the notch shape of the valve plate of the swash-plate-type variable piston pump as one of the pulsation variables, we investigate the effect of the pulsation by comparing two notch types (circular type and V type). Then, we extend our analysis to a nine-piston pump model. This paper not only confirms the effect of the pressure/flow pulsation according to pulsation variables but can also be applied to the development of a SimulationX-based simulation technique for notch-shape optimization for a swash-plate-type variable piston pump.

Research on the port valve of a water hydraulic axial pump

Water hydraulics using water as the working media is paid more attention because of its many advantages compared with oil ones. Water hydraulic pump is the key component in the applications of water hydraulics. Compared with the water hydraulic pump with port plate, the one with port valve has stronger anti-pollution ability and is more suitable for the open system where the working media cannot be filtered finely. For this kind of pump, the characteristics of port valve have direct and significant influences on the flow and pressure characteristics of the pump. In this article, the flow and pressure characteristics of different valves were compared experimentally and a disc valve was selected as the port valve. Then the mathematical model of a single-piston pump with port valve was built and the influences of different factors including spring rigidity, working pressure, etc. on the port valve were analysed. At last, a single-piston pump was developed to test the characteristics of the port valve. Based on these researches, some principles that should be abided in the design of the port valve were suggested.

Simple and rapid high-performance liquid chromatographic method for the determination of aspartame and its metabolites in foods

A method for the determination of aspartame (N-L-α-aspartyl-L-phenylalanine methyl ester) and its metabolites, applicable on a routine quality assurance basis, is described. Liquid samples (diet Coke, 7-Up, Pepsi, etc.) were injected directly onto a mini-cartridge reversed-phase column on a high-performance liquid chromatographic system, whereas solid samples (Equal, hot chocolate powder, pudding, etc.) were extracted with water. Optimising chromatographic conditions resulted in resolved components of interest within 12 min. The by-products were confirmed by mass spectrometry. Although the method was developed on a two-pump HPLC system fitted with a diode-array detector, it is straightforward and can be transformed to the simplest HPLC configuration. Using a single-piston pump (with damper), a fixed-wavelength detector and a recorder/integrator, the degradation of products can be monitored as they decompose. The results obtained were in harmony with previously reported tedious methods. The method is simple, rapid, quantitative and does not involve complex, hazardous or toxic chemistry.

Solution of a mathematical model of a single piston pump with a more detailed description of the valve function

Solution of a mathematical model of a single piston pump with a more detailed description of the valve function

Solution of a linear model of a single-piston pump by means of methods for differential equations in Hilbert spaces

Solution of a linear model of a single-piston pump by means of methods for differential equations in Hilbert spaces

A NEW MECHANICAL GREASE LUBRICATOR

A MECHANICAL grease lubricator now being manufactured in this country by Davies & Metcalfe Ltd., Romiley, Nr. Manchester, has several features that ensure long life with the minimum of maintenance. The lubricator may have six or twelve outlets, but it incorporates a single piston pump which is of such robust contraction that it will deliver grease at pressures up to 3,000 lb/sq. in. at the outlet connections. Each feed is individually adjustable, from zero to a maximum delivery of 2.47 oz. or 70 grams per hour.