scholarly journals Osmotic Engine Converting Energy from Salinity Difference to a Hydraulic Accumulator by utilizing Polyelectrolyte Hydrogels

Energy ◽  
2021 ◽  
pp. 121055
Author(s):  
Tri Quang Bui ◽  
Ole-Petter Magnussen ◽  
Vinh Duy Cao ◽  
Wei Wang ◽  
Anna-Lena Kjøniksen ◽  
...  
Keyword(s):  
Hydraulic Accumulator ◽  
Salinity Difference

scholarly journals Matchup Characteristics of Sea Surface Salinity Using a High-Resolution Ocean Model

2021 ◽  
Vol 13 (15) ◽  
pp. 2995
Author(s):  
Frederick M. Bingham ◽  
Severine Fournier ◽  
Susannah Brodnitz ◽  
Karly Ulfsax ◽  
Hong Zhang
Keyword(s):  
High Resolution ◽  
Time Window ◽  
Single Point ◽  
Ocean Model ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Argo Floats ◽  
Statistical Measures ◽  
Salinity Difference

Sea surface salinity (SSS) satellite measurements are validated using in situ observations usually made by surfacing Argo floats. Validation statistics are computed using matched values of SSS from satellites and floats. This study explores how the matchup process is done using a high-resolution numerical ocean model, the MITgcm. One year of model output is sampled as if the Aquarius and Soil Moisture Active Passive (SMAP) satellites flew over it and Argo floats popped up into it. Statistical measures of mismatch between satellite and float are computed, RMS difference (RMSD) and bias. The bias is small, less than 0.002 in absolute value, but negative with float values being greater than satellites. RMSD is computed using an “all salinity difference” method that averages level 2 satellite observations within a given time and space window for comparison with Argo floats. RMSD values range from 0.08 to 0.18 depending on the space–time window and the satellite. This range gives an estimate of the representation error inherent in comparing single point Argo floats to area-average satellite values. The study has implications for future SSS satellite missions and the need to specify how errors are computed to gauge the total accuracy of retrieved SSS values.

Model-Based Control of a Digital Hydraulic Transformer-Based Hybrid Actuator

2018 ◽  
Author(s):  
Matti Linjama
Keyword(s):  
High Efficiency ◽  
System Delay ◽  
Average Amount ◽  
Hydraulic Power ◽  
Model Based ◽  
Controlled Systems ◽  
Detailed Simulation ◽  
Power Management System ◽  
Hydraulic Accumulator ◽  
Hybrid Actuator

Energy-efficient motion control of hydraulic actuators is a challenging task. Throttle-free solutions have the potential for high efficiency. The main throttle-free approaches are pump-controlled systems, transformer-based solutions, and digital hydraulic solutions, such as switching transformers, multi-chamber cylinder and multi-pressure systems. This paper presents a novel solution based on a so-called digital hydraulic power management system (DHPMS). The DHPMS is freely rotating and a hydraulic accumulator is used for energy storage. In contrast to existing approaches, each actuator has its own DHPMS and a small accumulator to locally handle the power peaks. Only an average amount of power is needed from the hydraulic grid, radically reducing the size of the supply pump and the hydraulic piping and hosing. Pump flow is only 12.5% of the peak flow of the actuator in the case studied. Control of this type of system is challenging, and the model-based approach is used. The controller uses a simplified model and functionality is verified by using a detailed simulation model of the system. The results show that the approach is feasible but is demanding on the control valves. The system delay is also relatively long, which reduces the control performance in high-end systems. Nevertheless, this approach has potential in mobile machines, for example.

Induced Flow Reciprocating Pump Theory Supported by New Performance Data

1972 ◽  
Vol 94 (4) ◽  
pp. 706-714 ◽  
Author(s):  
J. D. Burton ◽  
J. Lobo-Guerrero U.
Keyword(s):  
High Speed ◽  
Performance Data ◽  
Experimental Measurements ◽  
Long Time ◽  
Induced Flow ◽  
Hydraulic Accumulator ◽  
Reciprocating Pump

Reciprocating pumps have been employed in conjunction with air vessels and fluid accumulators for a long time in order to reduce maximum cylinder pressures and energy wastage in friction. More recently, diaphragm pumps, run at high speed, have been built utilizing a hydraulic accumulator or capacitance in conjunction with a hydraulic inductance, in order to greatly increase the flow output. Volumetric efficiencies of over 250 percent have been obtained. The present paper describes briefly this induced flow principle and then compares theoretical solutions with experimental measurements taken in the first commercially available pump of this type.

scholarly journals Anomalous Thermo-osmotic Conversion Performance of Ionic Covalent-Organic-Framework Membranes in Response to Charge Variations

2022 ◽  
Author(s):  
Qi Sun ◽  
Weipeng Xian ◽  
Xiuhui Zuo ◽  
Changjia Zhu ◽  
Qing Guo ◽  
...  
Keyword(s):  
Charge Density ◽  
Energy Conversion ◽  
Energy Demand ◽  
High Performance ◽  
Critical Factor ◽  
Energy Conversion Efficiency ◽  
Nanoporous Membranes ◽  
Power Extraction ◽  
Membrane Charge ◽  
Salinity Difference

Abstract The development of efficient thermo-osmotic energy conversion devices has fascinated scientists and engineers for several decades in terms of satisfying the growing energy demand. The fabrication of ionic membranes with a high charge population is known to be a critical factor in the design of high-performance power generators for achieving high permselectivity and, consequently, high power extraction efficiency. Herein, we experimentally demonstrated that the thermo-osmotic energy conversion efficiency was improved by increasing the membrane charge density; however, this enhancement occurred only within a narrow window and subsequently exhibited a plateau over a threshold density. The complex interplay between pore−pore interactions and fluid structuration for ion transport across the upscaled nanoporous membranes helped explain the obtained results with the aid of numerical simulations. Consequently, the power generation efficiency of the multipore membrane deteriorated, deviating considerably from the case of simple linear extrapolation of the behavior of the single-pore counterparts. A plateau in the output electric power was observed at a moderate charge density, affording a value of 210 W m−2 at a 50-fold salinity difference with a temperature gradient of 40 K. This study has far-reaching implications for discerning an optimal range of membrane charge populations for augmenting the energy extraction, rather than intuitively focusing on achieving high densities.

scholarly journals ENERGY-EFFICIENT TECHNICAL SOLUTIONS FOR THE OPERATIONAL CHARACTERISTICS OF THE HYDRAULIC DRIVE OF THE TRACTOR

2021 ◽  
Author(s):  
R.V. Yudin ◽  
◽  
R.N. Puzakov ◽  
Keyword(s):  
Energy Saving ◽  
Energy Efficient ◽  
Hydraulic System ◽  
Hydraulic Drive ◽  
Working Fluid ◽  
Uneven Terrain ◽  
Operational Characteristics ◽  
High Dynamic ◽  
Hydraulic Accumulator ◽  
Technical Solutions

During the movement of the tractor on the uneven terrain, there are fluctuations that cause jumps of the working fluid in the hydraulic system and high dynamic loads. The solution to this problem is the use of an energy-saving hydraulic drive with a hydraulic accumulator and a system of aggregates this leads to increased efficiency and increased productivity of skidding grippers. A mathematical model of working processes with an energy-saving hydraulic drive is compiled.

MATLAB Simulation of Autonomous Servo Driven Oil-Hydraulic Power Unit

2016 ◽  
Author(s):  
Eurico Seabra ◽  
Jorge Costa ◽  
Hélder Puga ◽  
Celina Leão
Keyword(s):  
Power Unit ◽  
Control Strategy ◽  
High Efficiency ◽  
Gear Pump ◽  
Hydraulic Circuit ◽  
Servo Motor ◽  
Hydraulic Power ◽  
Hydraulic Accumulator ◽  
Control Methodology ◽  
Internal Gear

Servo driven hydraulic power units have been implemented in some sectors of industry in order to counteract rising energy costs and reduce our ecological footprint. The advantages associated with the use of these technologies has motivated us to research a new control approach that allows its use independently, with reduced implementation costs and high efficiency. This investigation develops new solutions to concurrently implement and improve volumetric control methodology for oil-hydraulic power units, which aims to produce and provide strictly necessary hydraulic power to the actuators. The approach used is based on a balance of flows present in a hydraulic circuit, reducing the pressure ripple generated by the pumps, valves and actuators, using a hydraulic accumulator. The work begins with the mathematical modeling of a volumetric oil-hydraulic power unit, designed to demonstrate the concepts of the project, its components and the associated advantages. The definitions of the models presented are intended to exemplify the new control strategy and infer about the possibilities that arise from the use of this new methodology for power oil-hydraulic units. In order to carry out the research and conclude about the results of the simulations, two simulations were performed using MATLAB Simulink software for two distinct hydraulic circuits and their control strategy: resistive control and volume control with the use of a servo motor. In the resistive control, an internal gear pump driven by an induction motor with constant speed uses a pressure regulating valve to derive the excess of the flow to the reservoir. Despite their low efficiency, this type of assembly has very low costs and has a very good dynamic compared with traditional volumetric drive systems, avoiding the use of dedicated engineering. The volumetric control makes use of an internal gear pump (to allow direct comparisons with the resistive control method), a servo motor, a hydraulic accumulator and a directional valve which prevent the flow from de accumulator draining into the reservoir during the downtimes. The controller allows you to establish a direct relationship between the accumulator volume and pressure of the hydraulic circuit. The control methodology discussed throughout this work reveals an alternative volumetric control solution to consider, whether in new equipment or in retrofitting even with the different objectives of existing technologies available in the market. The simulations allow us to conclude on energy-saving and environmental advantages of the volumetric control system presented, comparing it with existing systems on the market.

scholarly journals Using an Isohaline Flux Analysis to Predict the Salt Content in an Unsteady Estuary

2017 ◽  
Vol 47 (11) ◽  
pp. 2811-2828 ◽  
Author(s):  
Matthew D. Rayson ◽  
Edward S. Gross ◽  
Robert D. Hetland ◽  
Oliver B. Fringer
Keyword(s):  
River Flow ◽  
Salt Content ◽  
Box Model ◽  
Flux Analysis ◽  
Galveston Bay ◽  
Exchange Flow ◽  
Salt Intrusion ◽  
Adjustment Time ◽  
The Mean ◽  
Salinity Difference

AbstractAn estuary is classified as unsteady when the salinity adjustment time is longer than the forcing time scale. Predicting salt content or salt intrusion length using scaling arguments based on a steady-state relationship between flow and salinity is inaccurate in these systems. In this study, a time-dependent salinity box model based on an unsteady Knudsen balance is used to demonstrate the effects of river flow, inward total exchange flow (tidal plus steady), and the salinity difference between inflow and outflow on the salt balance. A key component of the box model is a relationship that links the normalized difference between inflowing and outflowing salinity at the mouth and the mean salinity content. The normalized salinity difference is shown to be proportional to the mean salinity squared, based on theoretical arguments from the literature. The box model is validated by hindcasting 5 years of mean salinity in Galveston Bay (estimated from coarse observations) in response to highly variable river discharge. It is shown that this estuary typically has a long adjustment time relative to the forcing time scales, and, therefore, the volume-averaged salinity rarely reaches equilibrium. The box model highlights the reasons why the adjustment time in a large, partially mixed estuary like Galveston Bay is slower when the mean salt content is higher. Furthermore, it elucidates why the salt content in the estuary is more responsive to changes in river flow than in landward exchange flow at the estuary mouth, even though the latter quantity is usually several times larger.

Low Maintenance Hydraulic Accumulator.

1981 ◽  
Author(s):  
E. C. Wagner ◽  
W. E. Willard
Keyword(s):  
Hydraulic Accumulator
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