Type Of Positive Displacement Pump Research Articles

Design, Construction and Evaluation of a Multi-piston Pump

The multi-piston pump, is a linear type of positive displacement pump, working on the principle of direct lift. The height to which the pump can directly lift the water is primarily controlled by factors that include the capacity of the operator, the clearance between the washers and the riser pipe and the speed of the washers. The materials for the construction of this pump can be obtained locally, even from the dump sites, hence its nickname “the pump from the dump”. It would not only serve as a means of lifting water easily, but will also improve the standard of living of the people. This pump could be an option for pumping water in relatively remote and deprived areas. This study highlights on the design, construction and evaluation of multi-piston pump. The pump went through vigorous design procedures and construction stages. The detailed working drawings of the pump were produced and constructions work carried out. Equations were established in order to know how the whole system behaves. It can be deduced from the study that pump discharge is influenced by piston diameter and the distance between the pistons. This pump can be used for small-irrigation schemes.
 Keywords: Pump; Hand-dug wells; Pipes; Discharge; Velocity.

Real-Time Reservoir Balancing and Leak-Free Nonaqueous Cell Design for Flow Batteries

Benchtop-scale testing of redox flow batteries presents numerous operational challenges related to electrolyte imbalance, leakage, and chemical compatibility. Electrolyte imbalance creates a capacity-limiting reservoir and necessitates manual or automatic transfer of electrolyte between reservoirs to rebalance. Leakage of electrolyte in the cell, often at tubing connections or interfaces between the graphite plates, gaskets, and membrane, also reduces capacity and experimental repeatability. The testing of increasingly common nonaqueous electrolytes requires not only strict wetted material compatibility across a range of solvents but also greater resistance to leaks – the lower surface tensions of many organic solvents (vs. water) makes them more prone to leakage. The above issues are more easily dealt with in large-scale, permanent installations that do not have the benchtop-scale requirements of manual assembly/disassembly, modularity, and configurational simplicity. Additionally, benchtop flow batteries often use peristaltic pumps, a type of positive displacement pump which create large pressure and flowrate pulsations compared to the continuous output of centrifugal pumps commonly used in large scale systems. The use of individual peristaltic pumps for each side of the flow battery can create an electrolyte imbalance when an asymmetric pressure drop occurs across the cell, causing a Darcy flow of electrolyte through the membrane separator. Other aspects of the flow battery can exacerbate this imbalance, such as using porous separators which are more permissive to electrolyte crossover, or more viscous electrolytes which create higher pressure differentials in the hydraulic circuit at a given flowrate. A new pump control strategy for flow batteries is designed and implemented which controls the speed and flowrate of the pumps in real time in response to the reservoir levels, as shown in Figure 1. This control scheme maintains balanced electrolyte reservoirs by minimizing the average differential pressure across the membrane. Minimal pressure drops are achieved by effectively matching the pressures in each half-cell of the battery by adjusting each pump’s speed and flowrate independently, so that both pumps are operating at the same pressure on their respective fluid mechanical system curves. Additionally, a more leak-resistant cell gasket design shown in Figure 2 is developed, while maintaining chemical compatibility for nonaqueous systems. These two developments are employed in a long-term cycling experiment using a nonaqueous disproportionation electrolyte. Figure 1

Investigation of leakage within an external gear pump with new decompression slots: numerical and experimental study

Gear pumps are amongst the most common types of positive displacement pumps. Having advantages such as small size, continuous and smooth output flow and high performance, these pumps are mainly used for handling high pressure fluids and flow metering. But the most important weakness of these pumps is the severe radial leakage at high pressures. Hence, it is important to study the leakage types and the methods of eliminating them in order to decrease any performance lost. In this study, a simple external gear pump has been studied numerically, analytically and experimentally. Using a commercial software, the pump leakage, volumetric efficiency and power consumption are studied numerically with respect to cavitation modeling. The numerical result shows good agreement with the experimental and analytical data. A new set of decompression slots on the gears teeth is introduced which eliminates the weakness of the prior methods. The results show that it has eliminated high pressure pulsations and catastrophic cavitation during the meshing process of the gears without increasing the radial leakage. As a result, the pump overall performance increases with smoother outflow. Also, the effect of gear teeth radius/teeth tip length on the pump performance has been studied in various working pressures within a case study. This investigation can be an essential and simple tool to design high performance gear pumps.

Study of the influence of the design parameters of the wet end of the gear pump on the force factors, acting in the gear pump with external gearing, using the software package MATLAB 2018a

The main advantages of gear pumps with external gearing in comparison with other types of positive displacement pumps are presented. The problem of calculating the loads, acting in gear pumps with external gearing, is considered. Examples of the application of calculation methods for solving a wide range of engineering problems in the energy, shipbuilding and aircraft building, shipbuilding and automobile industries are given. The advantages of using modern calculation methods for scientific research are considered. An example of introducing a virtual laboratory workshop for conducting experiments with electrical equipment is presented. The description of the program made in the numerical computing environment for the implementation of algorithms MATLAB R2018a for the calculation of the scalar and the direction of the force acting on the driven gear is given. The advantages of the developed program are presented. The results of the study of the effect of the presence of chamfer on the sleeve and eccentricity on the scalar and the direction of the acting force are presented. The results of research obtained using the developed program have been analyzed.

Suction port design for a synchronal rotary multiphase pump

The synchronal rotary multiphase pump is a new type of positive-displacement pump for multiphase boosting. Given that the discharge valve is eliminated in the synchronal rotary multiphase pump, the radial suction port as used in traditional rotary compressors is no longer suitable for the gas–liquid working condition. Thus, a special design for the axial suction port is presented to ensure the synchronal rotary multiphase pump’s flexibility in handling work fluids with any inlet gas volume fraction. The design concept and working principle of the axial suction port of the synchronal rotary multiphase pump are introduced herein, and a geometrical model of the suction port is established to calculate the critical dimensions for the synchronal rotary multiphase pump manufacture. The results show that the axial suction port’s design avoids the inner compression of work fluids and the back flow from the outlet to the inlet of the synchronal rotary multiphase pump during operation, which meets the requirements for operating under the gas–liquid working condition. The matching between the variation in the sectional area of the suction port and the varying trend of suction volume results in an acceptable sectional velocity of suction flow. Although the designed axial suction port reduces the suction angle range in a revolution, the decrease in the volumetric efficiency is negligible.

Flow characteristics of Roots pumps with multistage designs by CFD investigation

This study conducts a fluid analysis of multistage designs for a Roots pump, a type of positive displacement pump applied in blower and vacuum pumps. After a rotor profile is generated based on a mathematical model of a rotor, a three-dimensional numerical approach is developed using computational fluid dynamics (CFD) and applied to investigate the effect of multistage pump design on flow characteristics. The effects of serial versus parallel designs on fluid are illustrated using a two-lobed rotor. The fluid analysis, which pays particular attention to favorable stages, shows that in both serial and parallel connection designs, having more than three stages improves flow characteristics but to a relatively small degree because of increased leakage. It identifies the three-stage design as offering the greatest economy for pumping performance enhancement. A similar analysis is then performed on a three-lobed rotor design using the same three-stage design. A comparison of the flow characteristics of the two- versus three-lobed rotors based on serial versus parallel design and identical chamber volume identifies specific variations in flow rate, pressure, and pulsation.

The fine art of gear pump selection and operation

With seemingly so many different pump types to choose from and depending on the task in hand, finding the right pump seems impossible. Here, Richard Dearne of Micropump looks at the operation and selection of one type of positive displacement pump known as the external gear pump.

Performance characteristics of a continuous-flow fluidic pump

The fluidic pump is a type of positive-displacement pump in which basic fluid mechanics phenomena are utilized to eliminate valves and other moving parts that are exposed to the fluid being transferred. The version described in this article is powered by gas pressure serving as gas pistons and is virtually maintenance-free. It utilizes two displacement vessels and is designed to produce a steady and continuous liquid flow. This type of pump may be very useful for the transfer of radioactive or hazardous liquids where mechanical maintenance may be difficult or exposure of personnel to the fluid is undesirable. This paper presents experimental and model-predicted characteristics of such systems. The effects of several geometric parameters and operating conditions on the performance of the pump are briefly discussed.