Modeling and Simulation of the Steady-State and Transient Performance of a Three-Way Pressure Reducing Valve

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Osama Gad
Keyword(s):  
Steady State ◽  
Modeling And Simulation ◽  
Hydraulic Control ◽  
Transient Performance ◽  
Modes Of Operation ◽  
Transient Change ◽  
Discharge Coefficients ◽  
Proposed Model ◽  
Mathematical Formulas ◽  
Velocity Changes

This paper deals with modeling and simulation of a class of three-way pressure reducing valves. The study aims to point out the peculiarities of function and operation of this class of valves in the steady-state and transient modes of operation. A comprehensive nonlinear mathematical model is deduced in order to predict the performance of the studied valve in both modes. The proposed model takes into consideration most nonlinearities of the studied valve. A computer simulation, based on the proposed model, is performed to predict the steady-state and transient performance. During the simulation study, it was found that nonlinearity occurs due to the following factors: the transient change in the valve operating pressures and the change in the throttling areas of the valve restrictions and their discharge coefficients. The transient change in the valve operating pressures causes nonlinear velocity changes of the fluid flow passing through the throttling areas of the valve restrictions. These throttling areas usually have nonlinear mathematical formulas. The discharge coefficients of these throttling areas are assumed constant independent of the flow rates, Reynolds number, and dimensions of these areas. However, these parameters affect the discharge coefficient in a complicated manner. The validity of the proposed model is assessed experimentally in the steady-state and transient modes of operation. The results show good agreement between simulation and experiment in both modes. The study shows that the geometry of the throttling orifice, which connects the upstream port to the downstream port, plays an important role in the studied valve steady-state and transient performance. This result implies the need for further investigation of the effect of the dimensions of the throttling orifices on the steady-state and transient performance of hydraulic control valves.

Comprehensive Nonlinear Modeling of a Pilot Operated Relief Valve

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Osama Gad
Keyword(s):  
Steady State ◽  
Coulomb Friction ◽  
Nonlinear Modeling ◽  
Critical Parameters ◽  
Relief Valve ◽  
Proposed Model ◽  
Mode Of Operation ◽  
Velocity Changes ◽  
Pressure Changes ◽  
Good Agreement

This paper is directed toward a comprehensive nonlinear modeling and simulation of the performance of a class of a pilot operated relief valves. A mathematical model is deduced to predict the performance of the valve in the steady state and transient modes of operations. The developed model takes into consideration most nonlinearities of the valve and is studied within the MATLAB-SIMULINK environment. The validity of the proposed model is assessed experimentally in the steady state and transient modes of operations. The detailed modeling has resulted in a good agreement between simulation and experimental results. During the simulation studied, it was found that, nonlinearity occurs due to three factors: the pressure changes cause nonlinear velocity changes of the flow rate, the throttling area of the valve restriction usually changes nonlinearly, and the discharge coefficient of the throttling area of the valve restriction does not remain constant. In the transient mode of operation, the simulation studied identified some critical parameters which have a significant effect on the transient response of the valve. Most of the model’s parameters can be evaluated readily by direct measurement of the valve components dimensions thought the Coulomb friction factor and bulk modulus are tuned to match the model to the measurements.

Improved Load Sharing Control Techniques for Inverters used in a Microgrid

2009 ◽  
Vol 10 (1) ◽  
Author(s):  
Wei Yao ◽  
Zhaoming Qian
Keyword(s):  
Steady State ◽  
Transient Response ◽  
Single Phase ◽  
Load Sharing ◽  
Power Sharing ◽  
Experimental Results ◽  
Control Technique ◽  
Transient Performance ◽  
Control Techniques ◽  
Control Scheme

In this paper, an improved load sharing control scheme is presented, which is able to improve the transient response and power sharing accuracy of parallel-connected inverters used in microgrid. It also shows how the improved droop method can be easily adapted to account for the operation of parallel-connected inverters, providing good performance under the variation and disturbance of loads, as well as achieving good steady-state objectives and transient performance. Two DSP-based single-phase Microgrid inverters are designed and implemented. Simulation and experimental results are all reported, confirming the validity of the proposed control technique.

Modelling And Simulation of Topical Drug Diffusion in The Dermal Layer of Human Body

2021 ◽  
Vol 86 (2) ◽  
pp. 39-49
Author(s):  
Sudi Mungkasi
Keyword(s):  
Steady State ◽  
Human Body ◽  
Diffusion Problem ◽  
State Condition ◽  
Unsteady State ◽  
Steady State Condition ◽  
Drug Diffusion ◽  
Dermal Layer ◽  
Drug Concentrations ◽  
Proposed Model

We consider the problem of drug diffusion in the dermal layer of human body. Two existing mathematical models of the drug diffusion problem are recalled. We obtain that the existing models lead to inconsistent equations for the steady state condition. We also obtain that solutions to the existing models are unrealistic for some cases of the unsteady state condition, because negative drug concentrations occur due to the inappropriate assumption of the model. Therefore, in this paper, we propose a modified mathematical model, so that the model is consistent, and the solution is nonnegative for both steady and unsteady state conditions of the drug diffusion problem in the dermal layer of human body. For the steady state condition, the exact solution to the proposed model is given. For unsteady state condition, we use a finite difference method for solving the models numerically, where the discretisation is centred in space and forward in time. Simulation results confirm that our proposed model and method preserve the non-negativity of the solution to the problem, so the solution is more realistic than that of the old model.

Power Exchanges of Hybrid Fuel Cell-Ultracapacitor Power Sources Feeding Pulse Loads

2006 ◽  
Vol 4 (4) ◽  
pp. 516-519 ◽  
Author(s):  
D. Asprino ◽  
L. Conte ◽  
M. Pagano ◽  
G. Velotto
Keyword(s):  
Steady State ◽  
Fuel Cell ◽  
Power Quality ◽  
Primary Source ◽  
Experimental Results ◽  
Storage Device ◽  
Transient Performance ◽  
Power Sources ◽  
Hybrid Generator ◽  
Electrical Source

The paper focuses on the experimental results of a series of tests performed on a hybrid electrical source. The hybrid generator is made up of a fuel cell primary source equipped with an ultracapacitor storage device. The paper presents an examination of the steady-state and transient performance of the hybrid fuel cell-ultracapacitor source in terms of power quality. The aim is to investigate on fuel cell-ultracapacitor source’s behavior to feed pulsing loads.

Electro Hydraulic Control Harmonic Aging Stress Elimination Devices - Modeling and Simulation of the Shock Excitation Part

2011 ◽  
Vol 127 ◽  
pp. 439-443
Author(s):  
Hui Wang ◽  
Meng Li
Keyword(s):  
Modeling And Simulation ◽  
System Optimization ◽  
Hydraulic Control ◽  
Shock Excitation ◽  
Main Research ◽  
Interactive Environment ◽  
Development Data ◽  
Set Up ◽  
High Level ◽  
Dynamics Characteristic

The main research is the dynamics characteristic of the shock excitation part of electro hydraulic control harmonic aging stress elimination devices. Use the system dynamics knowledge to set up a dynamics model of the shock excitation part. Analyze the transfer function of system and then use MATLAB to draw graphics under the condition of different parameters. Through the simulation graphic's analysis, we can obtain the influence of various parameters on system model, so as to provide a reference for the system optimization. MATLAB is abbreviation of Matrix Laboratory, which is used for algorithm development, data visualization, data analysis and numerical calculation of high-level technical computing language and interactive environment. It is useful for us in modeling and simulation.

scholarly journals A Novel Analytical Modeling of a Loop Heat Pipe Employing Thin-Film Theory: Part II—Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2403 ◽  
Author(s):  
Eui Guk Jung ◽  
Joon Hong Boo
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Film Theory ◽  
Design Parameters ◽  
Working Fluid ◽  
Coolant Temperature ◽  
Loop Heat Pipe ◽  
Analysis Model ◽  
Proposed Model ◽  
Flat Evaporator

Part I of this study introduced a mathematical model capable of predicting the steady-state performance of a loop heat pipe (LHP) with enhanced rationality and accuracy. Additionally, investigation of the effect of design parameters on the LHP thermal performance was also reported in Part I. The objective of Part II is to experimentally verify the utility of the steady-state analytical model proposed in Part I. To this end, an experimental device comprising a flat-evaporator LHP (FLHP) was designed and fabricated. Methanol was used as the working fluid, and stainless steel as the wall and tubing-system material. The capillary structure in the evaporator was made of polypropylene wick of porosity 47%. To provide vapor removal passages, axial grooves with inverted trapezoidal cross-section were machined at the inner wall of the flat evaporator. Both the evaporator and condenser components measure 40 × 50 mm (W × L). The inner diameters of the tubes constituting the liquid- and vapor-transport lines measure 2 mm and 4 mm, respectively, and the lengths of these lines are 0.5 m. The maximum input thermal load was 90 W in the horizontal alignment with a coolant temperature of 10 °C. Validity of the said steady-state analysis model was verified for both the flat and cylindrical evaporator LHP (CLHP) models in the light of experimental results. The observed difference in temperature values between the proposed model and experiment was less than 4% based on the absolute temperature. Correspondingly, a maximum error of 6% was observed with regard to thermal resistance. The proposed model is considered capable of providing more accurate performance prediction of an LHP.

scholarly journals Electrothermal Averaged Model of a Diode-Transistor Switch Including IGBT and a Rapid Switching Diode

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3033 ◽  
Author(s):  
Paweł Górecki ◽  
Krzysztof Górecki
Keyword(s):  
Steady State ◽  
Integrated Circuit ◽  
Good Accuracy ◽  
Bipolar Transistor ◽  
Transistor Switch ◽  
Insulated Gate Bipolar Transistor ◽  
Self Heating ◽  
Proposed Model ◽  
Rapid Switching ◽  
Averaged Model

This study proposes an electrothermal averaged model of the diode–transistor switch including insulated gate bipolar transistor (IGBT) and a rapid switching diode. The presented model has the form of subcircuits dedicated for simulation program with integrated circuit emphasis (SPICE) and it makes it possible to compute characteristics of DC–DC converters at the steady state considering self-heating phenomena, both in the diode and in IGBT. This kind of model allows computations of voltages, currents and internal temperatures of all used semiconductor devices at the steady state. The formulas used in this model are adequate for both: continuous conducting mode (CCM) and discontinuous conducting mode (DCM). Correctness of the proposed model is verified experimentally for a boost converter including IGBT. Good accuracy in modeling these converter characteristics is obtained.

scholarly journals Simulation, Design, and Test of a Dual-Differential D-Dot Overvoltage Sensor Based on the Field-Circuit Coupling Method

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3413 ◽  
Author(s):  
Pengcheng Zhao ◽  
Jingang Wang ◽  
Qian Wang ◽  
Qianbo Xiao ◽  
Ruiqiang Zhang ◽  
...  
Keyword(s):  
Steady State ◽  
Power Transmission ◽  
Circuit Simulation ◽  
Structural Parameters ◽  
Equivalent Circuit Model ◽  
Simulation Software ◽  
Power Grids ◽  
Coupling Method ◽  
Transient Performance ◽  
Simulation Design

Accurate measurement of overvoltage in power grids is of great significance to study the characteristics of overvoltage and design of insulation coordination. Based on the research of D-dot voltage sensor, we designed a Dual-Differential D-dot overvoltage sensor. In order to quantify the structural parameters of the sensor, improve the performance and measurement accuracy of the sensor. The Field-Circuit Coupling method was proposed to be used in the parameter design of D-dot overvoltage sensor. The joint simulation of space electromagnetic field model and equivalent circuit model of the Dual-Differential D-dot overvoltage sensor was established with the finite element simulation software Ansoft Maxwell and circuit simulation software Simplorer. Finally, the actual sensor was manufactured. A test platform was built to verify the steady-state and transient performance of the sensor. The results show that the Dual-Differential D-dot sensor has excellent steady-state and transient performance, the error of phase and amplitude are small, and the sensor can achieve the non-contact measurement of power transmission line. Simultaneously, the rationality of the Field-Circuit Coupling method was further verified.

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