A Gasless Reservoir Solution for Electro-Hydraulic Compact Drives With Two Prime Movers

2020 ◽  
Author(s):  
Søren Ketelsen ◽  
Damiano Padovani ◽  
Morten Kjeld Ebbesen ◽  
Torben Ole Andersen ◽  
Lasse Schmidt
Keyword(s):  
Control Strategy ◽  
Numerical Study ◽  
Mimo System ◽  
Chamber Pressure ◽  
Gas Leakage ◽  
Reservoir Volume ◽  
Reservoir Solution ◽  
Flow Imbalance ◽  
Prime Movers ◽  
Gas Volume

Abstract Due to an increased focus on improving the energy efficiency and compactness of hydraulic linear actuators, the electro-hydraulic compact drive (ECD) has received increased attention lately. In this study the ECD consists of variable-speed electric motors and fixed-displacement pumps, which are directly connected to the cylinder, thus controlling the linear motion in a throttleless manner. Furthermore, ECDs are self-contained systems, i.e. based on a fully enclosed oil circuit, in order to avoid external contamination and air to enter the system and to increase system compactness. Conventionally a low-pressure gas-loaded accumulator is used as an oil reservoir to compensate for the flow imbalance occurring whenever utilizing single-rod cylinders in closed systems. The accumulator pressure is to be kept relatively low to stay within the required limits governed by the permitted pump housing’s pressure. Generally, this pressure is not allowed to exceed 1–3 bar. To avoid violating this limitation, the gas volume must be significantly larger than the actual oil volume, which needs to be stored in the accumulator. This requirement decreases the obtainable compactness of the ECD, especially for systems with a large cylinder stroke. Furthermore, the accumulator represents a potential of gas leakage, which ultimately could result in the ECD being non-functional. This paper presents a gasless reservoir solution, improving the system compactness and avoiding the risk of gas leakage. The proposed solution is based on a bootstrap reservoir which is charged by the lowest cylinder chamber pressure. This strategy is feasible for the class of ECDs that is capable of controlling the lowest cylinder chamber pressure alongside the cylinder motion. An ECD consisting of two electric prime movers is considered as a case study. It is shown how the gasless reservoir may be integrated into the system, and an analysis of how this affects the operating range and the dynamic couplings of the system is presented. This leads to the derivation of a control strategy for the Multi-Input-Multi-Output (MIMO) system based on state decoupling, by defining virtual inputs to control virtual outputs. A numerical study suggests that the reservoir volume may be reduced by approximately 50% for the given system dimensions. The proposed control strategy shows good position tracking performance while also being able to control the reservoir pressure within the pre-defined limits of 1 to 3 bar.

scholarly journals Experimental and numerical study on the thermal control strategy for a gas foil bearing enhanced with thermoelectric modules

2020 ◽  
Vol 138 ◽  
pp. 106581 ◽  
Author(s):  
Adam Martowicz ◽  
Jakub Roemer ◽  
Michał Lubieniecki ◽  
Grzegorz Żywica ◽  
Paweł Bagiński
Keyword(s):  
Control Strategy ◽  
Numerical Study ◽  
Thermal Control ◽  
Thermoelectric Modules ◽  
Foil Bearing

scholarly journals Cross-Layer Inference in WSN: From Methods to Experimental Validation

2020 ◽  
Author(s):  
Indrakshi Dey
Keyword(s):  
Mimo System ◽  
Hypothesis Test ◽  
Multiple Antennas ◽  
Statistical Signal Processing ◽  
Decision Fusion ◽  
Inference Problem ◽  
Robust Detection ◽  
Gas Leakage ◽  
Input Multiple Output ◽  
Set Up

In this chapter, the fundamentals of distributed inference problem in wireless sensor networks (WSN) is addressed and the statistical theoretical foundations to several applications is provided. The chapter adopts a statistical signal processing perspective and focusses on distributed version of the binary-hypothesis test for detecting an event as correctly as possible. The fusion center is assumed to be equipped with multiple antennas collecting and processing the information. The inference problem that is solved, primarily concerns the robust detection of a phenomenon of interest (for example, environmental hazard, oil/gas leakage, forest fire). The presence of multiple antennas at both transmit and receive sides resembles a multiple-input-multiple-output (MIMO) system and allows for utilization of array processing techniques providing spectral efficiency, fading mitigation and low energy sensor adoption. The problem is referred to as MIMO decision fusion. Subsequently, both design and evaluation (simulated and experimental) of these fusion approaches is presented for this futuristic WSN set-up.

scholarly journals Numerical Study on the Gas Leakage and Dispersion at the Street Intersection of a Building Group

2020 ◽  
Vol 123 (3) ◽  
pp. 1247-1266
Author(s):  
Weitao Zhang ◽  
Mengqi Liu ◽  
Kaiyi Wang ◽  
Fan Zhang ◽  
Lei Hou
Keyword(s):  
Numerical Study ◽  
Gas Leakage ◽  
Street Intersection

Numerical Study on Mechanism and Parameters Optimization of Temporary Plugging by Particles in Wellbore

2021 ◽  
pp. 1-16
Author(s):  
Tao Zhang ◽  
Ming Li ◽  
Jianchun Guo ◽  
Haoran Gou ◽  
Kefan Mu
Keyword(s):  
Particle Size ◽  
Numerical Study ◽  
Optimal Operation ◽  
Parameters Optimization ◽  
Mass Ratio ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Pump Rate ◽  
Single Well ◽  
Operation Parameters

Summary The temporary plugging by particles in the wellbore can open new perforation clusters and increase stimulated reservoir volume, but the temporary plugging process of particles is not clear. Therefore, in this paper, we take an ultradeep well in the Tarim Basin as the research object and establish a numerical model based on the coupled computational fluid dynamics-discrete element technology (CFD-DEM) approach, which accurately describes the movement process and mechanism of the temporary plugging particles in the wellbore. Furthermore, the influence of flow rate, concentration of injected particles, and the injected mass ratio of particle size on the temporary plugging effect were studied, respectively. In addition, based on the results of the orthogonal experimental analysis, we obtained the pump rate as the primary factor affecting the effect of temporary plugging, and we recommended the optimal operation parameters for temporary plugging by particles in the field: The pump rate is 2 m3/min, the concentration of the injected temporary plugging particles is 20%, and the ratio of the mass of the injected temporary plugging particles with particle size 1 to 5 mm to the mass of the temporary plugging particles with particle size 5 to 10 mm is 3:1. Finally, a single well that had implemented temporary plugging by particles was used to verify the recommended optimal temporary plugging operation parameters. The research results of this paper provide important guidance and suggestions for the design of temporary plugging schemes on the field.

Evaluation of the Effect of Gas Leakage on Operation of an Optical Engine

2010 ◽  
Author(s):  
E. Kapusuz ◽  
B. Ekici
Keyword(s):  
Gas Flow ◽  
Combustion Engine ◽  
Numerical Study ◽  
Mass Loss Rate ◽  
Ic Engine ◽  
Gas Leakage ◽  
Engine Model ◽  
Optical Engine ◽  
Laser Diagnostic ◽  
Flow Through

An experimental and numerical study is carried out to evaluate the significance of gas leakage for a non-lube optically accessible internal combustion engine and to obtain estimation for the gas flow out of the combustion chamber at each engine cycle and its effect on the in-cylinder component states during optical engine’s operation. Attention is paid to blow-by and circumferential flow through the gaps between the piston rings and the liner. Optical engines are typically operated without lubrication to avoid window fouling and generation of fluorescence by oil particles that interfere with laser diagnostic signals, in view of this circumstance significant blow-by is expected in optical engines due to lack of “wet-seal” on the cylinder walls which permits circumferential flow of gases through the piston ring pack region resulting in increased blow-by. Semi analytical model estimating the mass loss rate is incorporated into zero dimensional thermodynamic IC engine model which simulates in-cylinder processes. Predicted results are compared for leaking and non-leaking engine simulations.

scholarly journals Model-Based Optimisation and Control Strategy for the Primary Drying Phase of a Lyophilisation Process

Pharmaceutics ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 181 ◽  
Author(s):  
Brecht Vanbillemont ◽  
Niels Nicolaï ◽  
Laurens Leys ◽  
Thomas De Beer
Keyword(s):  
Real Time ◽  
Control Strategy ◽  
Freeze Drying ◽  
Fixed Time ◽  
Chamber Pressure ◽  
Interface Temperature ◽  
Real Time Control ◽  
Choked Flow ◽  
Model Based ◽  
Time Control

The standard operation of a batch freeze-dryer is protocol driven. All freeze-drying phases (i.e., freezing, primary and secondary drying) are programmed sequentially at fixed time points and within each phase critical process parameters (CPPs) are typically kept constant or linearly interpolated between two setpoints. This way of operating batch freeze-dryers is shown to be time consuming and inefficient. A model-based optimisation and real-time control strategy that includes model output uncertainty could help in accelerating the primary drying phase while controlling the risk of failure of the critical quality attributes (CQAs). In each iteration of the real-time control strategy, a design space is computed to select an optimal set of CPPs. The aim of the control strategy is to avoid product structure loss, which occurs when the sublimation interface temperature ( T i ) exceeds the the collapse temperature ( T c ) common during unexpected disturbances, while preventing the choked flow conditions leading to a loss of pressure control. The proposed methodology was experimentally verified when the chamber pressure and shelf fluid system were intentionally subjected to moderate process disturbances. Moreover, the end of the primary drying phase was predicted using both uncertainty analysis and a comparative pressure measurement technique. Both the prediction of T i and end of primary drying were in agreement with the experimental data. Hence, it was confirmed that the proposed real-time control strategy is capable of mitigating the effect of moderate disturbances during batch freeze-drying.

Study on a Type of Pneumatic Force Servo System

2013 ◽  
Vol 819 ◽  
pp. 192-196
Author(s):  
Meng Nie ◽  
Jian Yong Li ◽  
Hai Kuo Shen ◽  
Hua Min Sun
Keyword(s):  
Mathematical Model ◽  
Control Strategy ◽  
Digital Simulation ◽  
Servo System ◽  
Chamber Pressure ◽  
Source Pressure ◽  
Output Pressure ◽  
Gas Source ◽  
System Output ◽  
And Control

A type of pneumatic force servo system is discussed in this paper. In this system, output pressure depends on pressure difference between two chambers of cylinder; by controlling pilot-operated reducing valve will get different cylinder chamber pressure. Dynamic mathematical model and control Strategy of this system is founded in this paper. By mathematical model and control Strategy, the digital simulation results show how system performance with different gas source pressure and rodless cavity size..

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