Modeling and Control of a Refrigerant Evaporator

1985 ◽  
Vol 107 (4) ◽  
pp. 235-240 ◽  
Author(s):  
W.-D. Gruhle ◽  
R. Isermann
Keyword(s):  
Control Variable ◽  
Modeling And Control ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Expansion Valve ◽  
On Line ◽  
Process Computer ◽  
Dry Out ◽  
Random Fluctuations ◽  
And Control

Based on the balance equations for enthalpy, mass, and momentum a theoretical model of a refrigerant evaporator has been developed. The distributed parameter process is approximated by several lumped parameter models. The model is completed by equations for the expansion valve, the compressor and the superheater. Various effects, e.g., the random fluctuations of the liquid-dry-out-point can be explained by the model. The dynamic behavior of the evaporator is investigated as a function of the manipulating signal UEV (position of the expansion valve) and various disturbances (air temperature ϑA, condenser pressure pCd and compressor rotation speed nc), considering the superheating temperature ϑs as control variable and the evaporator performance Q˙E, which has to be optimized. Two controllers are considered. First, the control behavior with a conventional thermostatic expansion valve is shown, which often operates unstable. The control performance can be considerably improved by a controller whose structure and parameters are better adapted to the evaporation process. For the experiments a process computer is connected on-line to the process. It will be demonstrated that the performance of the evaporator and therefore its efficiency can be increased by at least 5 percent.

Modeling and Control of a High Pressure Combined Air/Fuel Injection System

2009 ◽  
Author(s):  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Lumped Parameter Model ◽  
Injection System ◽  
Fuel Injection System ◽  
Modeling And Control ◽  
Lumped Parameter ◽  
Mass Flow Rates ◽  
And Control ◽  
Liquid Piston

A high pressure combined air-fuel injection system is designed and tested for an experimental free liquid-piston engine compressor. The application discussed utilizes available high pressure air from the compressor’s reservoir, and high pressure fuel to mix and then inject into a combustion chamber. This paper addresses the modeling, design and control for this particular high-pressure air-fuel injection system, which features an electronically controlled air/fuel ratio control scheme. This system consists of a fuel line and an air line, whose mass flow rates are restricted by metering valves. These two lines are connected to a common downstream tube where air and fuel are mixed. By controlling the upstream pressures and the orifice areas of the metering valves, desired A/F ratios can be achieved. The effectiveness of the proposed system is demonstrated by a lumped-parameter model in simulation and validated by experiments.

On-Line Thermal Control for Injection Moulding Process

2013 ◽  
Author(s):  
Jaho Seo ◽  
Amir Khajepour ◽  
Jan P. Huissoon ◽  
Young-Jun Park
Keyword(s):  
Injection Moulding ◽  
Thermal Control ◽  
Production Quality ◽  
Modeling And Control ◽  
Moulding Process ◽  
Cycle Times ◽  
Plastic Injection Moulding ◽  
Injection Moulding Process ◽  
On Line ◽  
And Control

Thermal control is a key issue for injection moulding process due to its effects on production quality and rate. In this study, an on-line thermal control strategy is provided for effective thermal management in plastic injection moulding process. The strategy covers for methods in determining sensor locations as a prerequisite step for modeling and control, identifying a thermal dynamic model of a mould with uncertainties and designing a cavity wall temperature controller. A verification of the designed controller’s performance is carried out from the viewpoints of accuracy in on-line temperature tacking and response time under different injection moulding process with various cycle-times.

scholarly journals Neural networks on-line optimized PID controller with wind gust rejection for a quad-rotor

2021 ◽  
Author(s):  
Chiraz Ben Jabeur ◽  
Hassene Seddik
Keyword(s):  
Neural Networks ◽  
Experimental Results ◽  
Wind Gust ◽  
Pd Controller ◽  
Hostile Environment ◽  
Modeling And Control ◽  
Self Tuning ◽  
On Line ◽  
Hostile Environments ◽  
And Control

Abstract In this paper a complete methodology of modeling and control of quad-rotor aircraft is exposed. In fact, a PD on-line optimized Neural Networks Approach (PD-NN) is developed and applied to control the attitude of a quad-rotor that is evolving in hostile environment with wind gust disturbances and should maintain its position despite of these troubles. Whereas PD classical controllers are dedicated for the positions, altitude and speed control. The main objective of this work is to develop a smart Self-Tuning PD controller for attitude angles control, based on neural networks capable of controlling the quad-rotor for an optimized performance thus following a desired trajectory. Many problems could arise if the quad-rotor is evolving in hostile environments presenting irregular troubles such as wind gusts modeled and applied to the overall system. The quad-rotor has to rapidly achieve tasks while guaranteeing stability and precision and must behave quickly with regards to decision making fronting turbulences. This technique offers some advantages over conventional control methods such as PD controllers. Simulation results are achieved with the use of Matlab/Simulink environment and are established on a comparative study between PD and PD-NN controllers founded on wind disturbances application. These obstacles are applied with numerous degrees of strength to test the quad-rotor comportment. Experimental results are reached with the use of the V-REP environment with which some trajectories are tracked and then applied on a BLADE Inductrix FPV+. These simulations and experimental results are acceptable and have confirmed the efficiency of the proposed PD-NN approach. In fact, this controller has fairly smaller errors than the PD controller and has an improved ability to reject troubles. Moreover, it has confirmed to be extremely vigorous and efficient fronting disturbances in the form of wind disturbances.

A Fast Algorithm for On-Line Machining Process Modeling and Adaptive Control

1989 ◽  
Vol 111 (2) ◽  
pp. 133-139 ◽  
Author(s):  
S. D. Fassois ◽  
K. F. Eman ◽  
S. M. Wu
Keyword(s):  
Process Modeling ◽  
Closed Loop ◽  
Good Accuracy ◽  
A Priori ◽  
Adaptive Controller ◽  
Machining Process ◽  
Modeling And Control ◽  
Computational Load ◽  
On Line ◽  
And Control

A fast, on-line algorithm for machining process modeling and control is proposed. The modeling is accomplished via a new recursive estimator that offers good accuracy at a minimal computational load. Its Fast Kalman-type version, that further reduces its computational complexity, is also presented. The adaptive controller, which is based on on-line identification and closed-loop pole assignment, is characterized by a low computational load and no need for a priori process information. The analytical results are supplemented by numerical simulations, where the proposed scheme is used for the control of a turning operation and shown to offer very good performance under noisy conditions and suddenly changing machining dynamics.

scholarly journals Addressing Abrupt PV Disturbances, and Mitigating Net Load Profile’s Ramp and Peak Demands, Using Distributed Storage Devices

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1024 ◽  
Author(s):  
Roshan Sharma ◽  
Masoud Karimi-Ghartemani
Keyword(s):  
Distributed Storage ◽  
Synchronous Generators ◽  
Load Profile ◽  
Modeling And Control ◽  
Storage Devices ◽  
High Penetration ◽  
On Line ◽  
Battery Energy ◽  
And Control ◽  
Net Load

At high penetration level of photovoltaic (PV) generators, their abrupt disturbances (caused by moving clouds) cause voltage and frequency perturbations and increase system losses. Meanwhile, the daily irradiation profile increases the slope in the net-load profile, for example, California duck curve, which imposes the challenge of quickly bringing on-line conventional generators in the early evening hours. Accordingly, this paper presents an approach to achieve two objectives: (1) address abrupt disturbances caused by PV generators, and (2) shape the net load profile. The approach is based on employing battery energy storage (BES) systems coupled with PV generators and equipped with proper controls. The proposed BES addresses these two issues by realizing flexible power ramp-up and ramp-down rates by the combined PV and BES. This paper presents the principles, modeling and control design aspects of the proposed system. A hybrid dc/ac study system is simulated and the effectiveness of the proposed BES in reducing the impacts of disturbances on both the dc and ac subsystems is verified. It is then shown that the proposed PV-BES modifies the daily load profile to mitigate the required challenge for quickly bringing on-line synchronous generators.

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