Adaptive Supervisory Control of Superheat Temperature for a Supermarket Refrigeration System

2011 ◽  
Author(s):  
Kaveh Kianfar ◽  
Roozbeh Izadi-Zamanabadi ◽  
Mehrdad Saif
Keyword(s):  
Supervisory Control ◽  
Adaptive Controller ◽  
Refrigeration System ◽  
Forgetting Factor ◽  
Time Step ◽  
Switching Algorithm ◽  
Superheat Temperature ◽  
Supervisory Controller ◽  
Satisfactory Performance ◽  
Expansion Valve

In this paper an adaptive supervisory controller is designed to control the superheat temperature of a supermarket refrigeration system. The adaptive controller utilizes a switching algorithm with a forgetting factor. At each time step, the switching algorithm selects the best model among multi models using a supervisory monitoring signal. Each model corresponds to a controller; hence the corresponding controller to the selected model generates the required signal to determine the opening degree of an expansion valve. Simulations results of the proposed controller on a model of superheat of a supermarket refrigeration system for different operating point, show very satisfactory performance.

Real-Time Expert System for Fault-Tolerant Supervisory Control

1993 ◽  
Vol 115 (2A) ◽  
pp. 219-227 ◽  
Author(s):  
K. Ramamurthi ◽  
A. M. Agogino
Keyword(s):  
Expert System ◽  
Mathematical Models ◽  
Real Time ◽  
Supervisory Control ◽  
Fault Tolerant ◽  
Adaptive Controller ◽  
Influence Diagram ◽  
Supervisory Controller ◽  
System Integrity ◽  
The Cost

Many mechanical systems are sufficiently complex that it is impractical to describe their dynamics by exact mathematical models. In the presence of such modeling uncertainties, advanced controllers like adaptive controllers perform better than linear feedback controllers since they actively reduce the uncertainty by online parameter estimation. Unfortunately, the advanced control strategies, due to their lack of robustness, can become unstable in the presence of unpredictable external disturbances, and hence, there exists a need for a fault-tolerant approach to preserve the overall system integrity even at the cost of design performance. This motivated the research, presented in this paper, to investigate the suitability of the IDES (Influence Diagram Based Expert System) as an expert supervisory controller to predict incipient instability, a significant failure mode, and take corrective action in real-time when closed loop stability appears to be in danger. The expert supervisory control scheme is demonstrated on a model-referenced adaptive controller as applied to a robotic manipulator. The real-time expert system, with the information from sensors, dynamically optimizes the cost of control and as a result chooses between a robust auxiliary controller and the nonrobust adaptive controller depending on inferences made from the observable variables. IDES, as a real-time expert supervisory controller, preserves the stability of the system even under potentially destabilizing unexpected disturbances, exhibiting on demand a fault-tolerant behavior by trading design performance for overall system integrity. The results indicate the potential for influence diagram expert systems in monitoring and controlling mechanical systems where exact mathematical models are difficult or not practical to obtain.

Design and Build of Teaching and Experimental Marine Cold Store

2014 ◽  
Vol 556-562 ◽  
pp. 907-911
Author(s):  
Chang Wei He ◽  
Meng Zhang ◽  
Xiao Ping Jia ◽  
Yuan Liu
Keyword(s):  
Thermal Performance ◽  
System Performance ◽  
Heat Load ◽  
Refrigeration System ◽  
Electrical System ◽  
Technology Application ◽  
Design Scheme ◽  
Expansion Valve ◽  
Cold Store ◽  
Practical Teaching

In the paper, the design scheme of the new cold store is proposed firstly, with the consideration of the latest technology application and the convenience and maneuverability of practical teaching. Then the refrigeration system is designed based on the calculation of the heat load of the cold store. The suited components such as compressor, evaporator, condenser and expansion valve are selected and the electrical system is designed. After that the whole unit is installed and adjusted to make sure that the installation is propitious to improve the system performance and convenient for training. Finally the thermal performance of the new cold store system is tested and compared with the old system test. The result shows that the matching of the new refrigeration system is reasonable and the new cold store is up to the mustard. With the help of training on the cold store, the students will meet the essential requirements of STCW 78/95 convention on application and management of the marine cold store.

Supervisory control of a grid-connected wind turbine generator

2016 ◽  
Vol 40 (6) ◽  
pp. 483-496 ◽  
Author(s):  
Djalloul Achour ◽  
Mohamed Kesraoui ◽  
Ahmed Chaib
Keyword(s):  
Wind Turbine ◽  
Supervisory Control ◽  
Turbine Generator ◽  
Wind Turbine Generator ◽  
Proportional Integral ◽  
Supervisory Controller ◽  
Power Load ◽  
Excess Power ◽  
The Village ◽  
Different Sources

In this article, the supervisory controller is proposed to manage a hybrid wind turbine generator and a grid supplying a village load. The main problem is the compatibility of coupling of different sources. To avoid this problem, the grid supplies a motor to supplement the torque of the wind turbine when the wind speed is low, and the village demand is higher than the wind turbine generator power. On the other hand, the excess power from the wind turbine generator can be absorbed by a dynamic power load that is connected to the grid. The fuzzy proportional–integral/proportional–integral–derivative supervisory controller objectives are to stabilize the frequency and voltage of the system and satisfy the village power demand. This is achieved by balancing the active and reactive powers of the wind turbine generator and village load through a grid contribution. The whole system has been simulated using SIMPOWER in MATLAB/SIMUILINK software. The efficiency of the proposed controller has been proved by the obtained results.

scholarly journals Cop Enhancement of Vapour Compression Refrigeration System

2021 ◽  
pp. 1-6
Author(s):  
B Sairamakrishna ◽  
◽  
T Gopala Rao ◽  
N Rama Krishna ◽  
◽  
...  
Keyword(s):  
Tube Diameter ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Expansion Valve ◽  
Compressor Inlet ◽  
Work Input ◽  
Compressor Work ◽  
Vapour Compression ◽  
Design And Testing ◽  
Nozzle Inlet

This experimental investigation exemplifies the design and testing of diffuser at compressor inlet and nozzle at condenser outlet in vapour compression refrigeration system with the help of R134a refrigerant. The diffuser with divergence angle of 12°,14° and the nozzle with convergent angle 12°,14° are designed for same inlet and outlet diameters. Initially diffusers are tested at compressor inlet diffuser is used with inlet diameter equal to exit tube diameter of evaporator and outlet tube diameter is equal to suction tube diameter of the compressor. Diffuser helps to increases the pressure of the refrigerant before entering the compressor it will be helps to reduces the compression work and achieve higher performance of the vapour compression refrigeration system. Then nozzles are testing at condenser outlet, whereas nozzle inlet diameter equal to discharging tube diameter of condenser and outlet diameter equal to inlet diameter of expansion valve. Additional pressure drop in the nozzle helped to achieve higher performance of the vapour compression refrigeration system. The system is analyzes using the first and second laws of thermodynamics, to determine the refrigerating effect, the compressor work input, coefficient of performance (COP).

The choice of a thermostatic expansion valve for a CFC12 refrigeration system retrofitted with HFC134a

1993 ◽  
Vol 17 (3) ◽  
pp. 153-164 ◽  
Author(s):  
N. J. Hewitt ◽  
J. T. McMullan ◽  
D. G. Moran ◽  
N. E. Murphy
Keyword(s):  
Refrigeration System ◽  
Expansion Valve
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