Development of Prototype Pump Using a Vibrating Pipe With a Valve

1994 ◽  
Vol 116 (4) ◽  
pp. 741-745 ◽  
Author(s):  
Hiroyuki Hashimoto ◽  
Hirokuni Hiyama ◽  
Rokuro Sato
Keyword(s):  
Maximum Flow ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Maximum Pressure ◽  
Electromagnetic Excitation ◽  
Durability Test ◽  
Current Frequency ◽  
Working Medium ◽  
One Year ◽  
Chemical Pump

Tests were conducted on a prototype pump which has an extremely simple structure and excellent controllability. Its structural and hydrodynamic features are different from those of previous conventional reciprocating pumps. The pump structure constitutes a leak-proof short vibrating pipe equipped with a nonreturn valve on the edge of its outlet. The authors developed a prototype pump which uses a 25 mm diameter vibration pipe and an electromagnetic excitation device. The pump performance, intentionally changed by adjusting the coil voltage or the coil current frequency, featured a maximum pressure of approximately 1.0 bars, a maximum flow rate of approximately 40 liters per minute, and a maximum efficiency of approximately 30 percent. Results of both a one-year test run, using water as the working medium, and a three-month durability test, using concentrated nitric acid as the working fluid, assuming application as a chemical pump, indicated favorable results.

scholarly journals Thermodynamic Analysis of Irreversible Desiccant Systems

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 595 ◽  
Author(s):  
Niccolò Giannetti ◽  
Seiichi Yamaguchi ◽  
Andrea Rocchetti ◽  
Kiyoshi Saito
Keyword(s):  
Control Volume ◽  
Ideal Gas ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Specific System ◽  
Equilibrium Relationship ◽  
Working Medium ◽  
Vapour Mixture ◽  
Energy Balances ◽  
Relationship Of

A new general thermodynamic mapping of desiccant systems’ performance is conducted to estimate the potentiality and determine the proper application field of the technology. This targets certain room conditions and given outdoor temperature and humidity prior to the selection of the specific desiccant material and technical details of the system configuration. This allows the choice of the operative state of the system to be independent from the limitations of the specific design and working fluid. An expression of the entropy balance suitable for describing the operability of a desiccant system at steady state is obtained by applying a control volume approach, defining sensible and latent effectiveness parameters, and assuming ideal gas behaviour of the air-vapour mixture. This formulation, together with mass and energy balances, is used to conduct a general screening of the system performance. The theoretical advantage and limitation of desiccant dehumidification air conditioning, maximum efficiency for given conditions constraints, least irreversible configuration for a given operative target, and characteristics of the system for a target efficiency can be obtained from this thermodynamic mapping. Once the thermo-physical properties and the thermodynamic equilibrium relationship of the liquid desiccant mixture or solid coating material are known, this method can be applied to a specific technical case to select the most appropriate working medium and guide the specific system design to achieve the target performance.

A magnetic screw pump for magnetorheological clutch durability enhancement

2020 ◽  
Vol 31 (7) ◽  
pp. 945-955 ◽  
Author(s):  
Raphaël Pilon ◽  
Alexandre Landry-Blais ◽  
Benoit Gillet ◽  
Anaële Pin ◽  
Jean-Philippe Lucking Bigué ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Maximum Flow ◽  
Magnetorheological Fluid ◽  
Maximum Pressure ◽  
Durability Test ◽  
Screw Pump ◽  
Flow Characterization ◽  
Flight Controls ◽  
Field Lines ◽  
Shear Interface

Magnetorheological clutches have great potential for demanding applications such as powertrains and aircraft primary flight controls. However, in such high-power applications (>1 kW), durability is a challenge because of the continuous slippage at the clutch shear interface. To improve durability, this research studies the potential of using a magnetic screw pump to promote fluid mixing within a magnetorheological clutch. The screw flights are made of magnetorheological fluid formed by the concentration of the magnetic field lines around helical grooves machined into the shear interface (drum) of the clutch. While the magnetic pump does not display a typical screw pump behavior, a semi-empirical yield screw pump model is proposed to better understand the macroscopic behavior. Experimental flow characterization results show that the pressure–flow relation is significantly affected by the number of grooves, magnetic field intensity, and rotational speed. For a clutch containing 50 mL of magnetorheological fluid, maximum flow rates of up to 25 mL/min and a maximum pressure of 150 kPa are achieved. Finally, durability test results show that the magnetic screw pump can increase durability by up to 42% when compared to a standard magnetorheological clutch, confirming that such a device is a viable solution for promoting durability.

Study on the Modes of Operation of a Multi-Machine Installations with Mechanical Reduction

2019 ◽  
pp. 12-22
Author(s):  
A. M. Oleynikov ◽  
L. N. Kanov
Keyword(s):  
Mathematical Description ◽  
Reactive Power ◽  
Maximum Efficiency ◽  
Wind Flow ◽  
System Of Equations ◽  
Mechanical Equilibrium ◽  
Synchronous Generators ◽  
Electromagnetic Excitation ◽  
Number Of Generators ◽  
Wide Range

The paper gives the description of the original wind electrical installation with mechanical reduction in which the output of vertical axis wind turbine with rather low rotation speed over multiplicator is distributed to a certain number of generators. The number of acting generators is determined by the output of actual operating wind stream at each moment. According to this constructive scheme, it is possible to provide effective and with maximum efficiency installation work in a wide range of wind speeds and under any schedule issued to the consumer of electricity. As there are no any experience in using such complexes, mathematical description of its main elements is given, namely windwheels, generators with electromagnetic excitation of magnetic electrical type, then their interaction with windwheel, and also the results of mathematical modeling of work system regimes under using the offered system of equations. The basis for the mathematical description of the main elements of the installation – synchronous generators – are the system of equations of electrical and mechanical equilibrium in relative units in rotating coordinates without considering saturation of the magnetic circuit. The equation of mechanical equilibrium systems includes torque and brake windwheel electromagnetic moments of generators with taking into account the reduction coefficients and friction. In addition, we specify the alternator rotor dynamics resulting from continuous torque of windwheel fluctuations under the influence of unsteady wind flow and wind speed serving as the original variable is modeled by a set of sinusoids. Model simplification is achieved by equivalization of similar generators and by disregarding these transitions with a small time constant. Calculation the installation with synchronous generators of two types of small and medium capacity taking into account the operational factors allowed us to demonstrate the logic of interactions in the main elements of the reported complex in the process of converting wind flow into the generated active and reactive power. We have shown the possibility of stable system work under changeable wind stream condition by regulating of the plant blade angle and with simultaneous varying of generator number of different types. All these are in great interest for project organizations and power producers.

scholarly journals Improving Output Performance of a Resonant Piezoelectric Pump by Adding Proof Masses to a U-Shaped Piezoelectric Resonator

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 500
Author(s):  
Jian Chen ◽  
Wenzhi Gao ◽  
Changhai Liu ◽  
Liangguo He ◽  
Yishan Zeng
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Working Fluid ◽  
Driving Voltage ◽  
Piezoelectric Resonator ◽  
Piezoelectric Pump ◽  
Compact Structure ◽  
Output Performance ◽  
Volume Efficiency ◽  
Working Efficiency

This study proposes the improvement of the output performance of a resonant piezoelectric pump by adding proof masses to the free ends of the prongs of a U-shaped piezoelectric resonator. Simulation analyses show that the out-of-phase resonant frequency of the developed resonator can be tuned more efficiently within a more compact structure to the optimal operating frequency of the check valves by adjusting the thickness of the proof masses, which ensures that both the resonator and the check valves can operate at the best condition in a piezoelectric pump. A separable prototype piezoelectric pump composed of the proposed resonator and two diaphragm pumps was designed and fabricated with outline dimensions of 30 mm × 37 mm × 54 mm. Experimental results demonstrate remarkable improvements in the output performance and working efficiency of the piezoelectric pump. With the working fluid of liquid water and under a sinusoidal driving voltage of 298.5 Vpp, the miniature pump can achieve the maximum flow rate of 2258.9 mL/min with the highest volume efficiency of 77.1% and power consumption of 2.12 W under zero backpressure at 311/312 Hz, and the highest backpressure of 157.3 kPa under zero flow rate at 383 Hz.

scholarly journals Discussion of meteorolo­gical observations in India at various heights

1851 ◽  
Vol 5 ◽  
pp. 933-936
Keyword(s):  
Sea Level ◽  
Maximum Pressure ◽  
Daily Range ◽  
Diurnal Range ◽  
Annual Range ◽  
The Subject ◽  
Meteorological Observations ◽  
Extended Area ◽  
One Year ◽  
Board Ship

The author adverts to a former paper “On the Meteorolog of the Deccan,” published in the Philosophical Transactions for 1835, and after referring to the conclusions at which he arrived in that communication, states that, in the discussion of the meteorological observations which form the subject of the present paper, and which were made over a very extended area, at different heights, some being hourly and running through several years at the same station, it is very satisfactory to find that they fully establish the accuracy of the former deductions. He remarks that, as some of the obser­vations now discussed were hourly records continued through con­siderable periods of time, an opportunity has been afforded of in­vestigating abnormal conditions, which the former limited number of diurnal observations did not permit; and gives the following review of what appears to be normal and abnormal conditions. The annual and daily range of the barometer diminishes from the sea-level up to the greatest height observed, 8640 feet at Dodabetta, from a mean annual and mean daily range at Madras of 0·735 and 0·122 respectively to 0·410 and 0·060 at Dodabetta;—the annual range would appear to increase, about and beyond the northern tropic, as the annual range at Calcutta (not by hourly observations) is 0·911; but the diurnal range is somewhat less (0·115) than at Madras. At no one of the places of observation, even taking the maximum pressure of one year with the minimum pressure of another year, does there appear to have been a range of pressure equivalent to an inch of mercury; nevertheless in the Cyclones, or rotatory storms, there occurs at times a range of pressure of nearly two inches of mercury within forty-eight hours; but it is shown from a compa­ rison of the simultaneous records on board ship, where these great depressions were noted, with the records at the observatories on shore, that the great depressions occurred within very limited areas.

A New Concept of Externally Heated Engine—Comparisons with the Stirling Engine

1996 ◽  
Vol 210 (5) ◽  
pp. 363-371 ◽  
Author(s):  
L Brzeski ◽  
Z Kazimierski
Keyword(s):  
Low Power ◽  
Power Density ◽  
Internal Combustion Engines ◽  
Thermodynamic Cycle ◽  
Rotational Frequency ◽  
Stirling Engine ◽  
Maximum Pressure ◽  
Combustion Engines ◽  
Working Medium ◽  
Engine Cylinder

This paper presents a new concept of the externally heated valve (EHV) engine. Air can be used as a working medium in the closed cycle of this engine. Heat delivered to the working air can come from a combustion chamber or another heat generator of an arbitrary type. The engine construction and the thermodynamic cycle performed by it are original and entirely different from the well-known Stirling engine. The main disadvantage of the Stirling engine is its low power density, that is the low power obtained per litre of the engine cylinder volume. In the case of the engine presented here it is possible to achieve power density and efficiency similar to those typical of advanced internal combustion engines. Comparisons between the power of the Stirling engine and the power of the new engine have been performed for the same engine capacity, rotational frequency and maximum and minimum temperatures of the cycle. At the same minimum pressure of the working gas in both engines, the power of the EHV engine is several times higher than that of the Stirling engine, while, on the other hand, at the same maximum pressure of the working gas in both engines, the power of the EHV engine is 20 per cent higher than that of the Stirling engine power. The efficiencies of both engines do not differ significantly from each other.

Small Scale Supercritical CO2 Radial Inflow Turbine Meanline Design Considerations

2018 ◽  
Author(s):  
Tina Unglaube ◽  
Hsiao-Wei D. Chiang
Keyword(s):  
High Velocity ◽  
Gas Turbines ◽  
Velocity Ratio ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Optimum Velocity ◽  
Set Up ◽  
Very High

In recent years closed loop supercritical carbon dioxide Brayton cycles have drawn the attention of many researchers as they are characterized by a higher theoretic efficiency and smaller turbomachinery size compared to the conventional steam Rankine cycle for power generation. Currently, first prototypes of this emerging technology are under development and thus small scale sCO2 turbomachinery needs to be developed. However, the design of sCO2 turbines faces several new challenges, such as the very high rotational speed and the high power density. Thus, the eligibility of well-established radial inflow gas turbine design principles has to be reviewed regarding their suitability for sCO2 turbines. Therefore, this work reviews different suggestion for optimum velocity ratios for gas turbines and aims to re-establish it for sCO2 turbines. A mean line design procedure is developed to obtain the geometric dimensions for small scale sCO2 radial inflow turbines. By varying the specific speed and the velocity ratio, different turbine configurations are set up. They are compared numerically by means of CFD analysis to conclude on optimum design parameters with regard to maximum total-to-static efficiency. Six sets of simulations with different specific speeds between 0.15 and 0.52 are set up. Higher specific speeds could not be analyzed, as they require very high rotational speeds (more than 140k RPM) for small scale sCO2 turbines (up to 150kWe). For each set of simulations, the velocity ratio that effectuates maximum efficiency is identified and compared to the optimum parameters recommended for radial inflow turbines using subcritical air as the working fluid. It is found that the values for optimum velocity ratios suggested by Rohlik (1968) are rather far away from the optimum values indicated by the conducted simulations. However, the optimum values suggested by Aungier (2005), although also established for subcritical gas turbines, show an approximate agreement with the simulation results for sCO2 turbines. Though, this agreement should be studied for a wider range of specific speeds and a finer resolution of velocity ratios. Furthermore, for high specific speeds in combination with high velocity ratios, the pressure drop of the designed turbines is too high, so that the outlet pressure is beyond the critical point. For low specific speeds in combination with low velocity ratios, the power output of the designed turbines becomes very small. Geometrically, turbines with low specific speeds and high velocity ratios are characterized by very small blade heights, turbines with high specific speeds and small velocity ratios by very small diameters.

The Role of Internal Irreversibilities in the Performance and Stability of Power Plant Models Working at Maximum ϵ-Ecological Function

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gabriel Valencia-Ortega ◽  
Sergio Levario-Medina ◽  
Marco Antonio Barranco-Jiménez
Keyword(s):  
Power Plants ◽  
Heat Engine ◽  
Combined Cycle ◽  
Ecological Function ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Engine Model ◽  
Improved Stability ◽  
The Stability

Abstract The proposal of models that account for the irreversibilities within the core engine has been the topic of interest to quantify the useful energy available during its conversion. In this work, we analyze the energetic optimization and stability (local and global) of three power plants, nuclear, combined-cycle, and simple-cycle ones, by means of the Curzon–Ahlborn heat engine model which considers a linear heat transfer law. The internal irreversibilities of the working fluid measured through the r-parameter are associated with the so-called “uncompensated Clausius heat.” In addition, the generalization of the ecological function is used to find operating conditions in three different zones, which allows to carry out a numerical analysis focused on the stability of power plants in each operation zone. We noted that not all power plants reveal stability in all the operation zones when irreversibilities are considered through the r-parameter on real-world power plants. However, an improved stability is shown in the zone limited by the maximum power output and maximum efficiency regimes.

Lebanon’s October 2019 Uprising

2021 ◽  
pp. 436-445
Author(s):  
Karim Makdisi
Keyword(s):  
Civil War ◽  
The State ◽  
Maximum Pressure ◽  
Ruling Class ◽  
Neoliberal Reforms ◽  
Ponzi Scheme ◽  
Neoliberal Policies ◽  
One Year ◽  
External Intervention

This essay frames Lebanon’s October 2019 uprising as triggered by the government’s announcement of a series of regressive taxes. After fifteen years of civil war (1975–90) and three decades of postwar neoliberal policies, people rose up against a kleptocratic ruling class of sectarian leaders and financiers that had captured and bankrupted the state through a nationwide Ponzi scheme. The essay charts the uprising’s demise amid protestor division, mass poverty and unemployment, galloping inflation, palpable insecurity, COVID-19 lockdowns, and external intervention. Hizbullah became the elephant in the room, with sectarian tension and some protestor resentment stoked by Trump’s US “maximum pressure” policies. A massive blast in Beirut’s port prompted French President “Papa” Macron to personally unveil a stabilization plan through IMF neoliberal reforms, a carrot to Trump’s stick. The essay concludes that, one year on, Macron’s neoliberal plan is the only game in town, and protestors need to urgently remobilize for the struggles ahead.

Biomass combined cycles based on externally fired gas turbines and organic Rankine expanders

2011 ◽  
Vol 225 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini
Keyword(s):  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
System A ◽  
Combined Cycles

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.

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