System Identification and Control Design of Vapor Compression Cycle Systems

2014 ◽  
Vol 136 (5) ◽  
pp. 051003 ◽  
Author(s):  
Magdi S. Mahmoud ◽  
Mirza H. Baig
Keyword(s):  
System Identification ◽  
Control Design ◽  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Cycle Systems ◽  
And Control

Moving-Boundary Heat Exchanger Models With Variable Outlet Phase

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Brian D. Eldredge ◽  
Bryan P. Rasmussen ◽  
Andrew G. Alleyne
Keyword(s):  
Heat Exchanger ◽  
Moving Boundary ◽  
System Level ◽  
Phase System ◽  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Cycle Systems ◽  
Level Model ◽  
And Control

Vapor compression cycle systems using accumulators and receivers inherently operate at or near a transition point involving changes of phase at the heat exchanger outlets. This work introduces a condenser/receiver model and an evaporator/accumulator model developed in the moving-boundary framework. These models use a novel extension of physical variable definitions to account for variations in refrigerant exit phase. System-level model validation results, which demonstrate the validity of the new models, are presented. The model accuracy is improved by recognizing the sensitivity of the models to refrigerant mass flow rate. The approach developed and the validated models provide a valuable tool for dynamic analysis and control design for vapor compression cycle systems.

System Dynamic Modeling of Vapor Compression Cycles

2012 ◽  
Author(s):  
Eric S. Miller ◽  
Soumya S. Patnaik ◽  
Milind A. Jog
Keyword(s):  
Thermal Management ◽  
Dynamic Behavior ◽  
Lagrangian Method ◽  
System Response ◽  
Vapor Compression ◽  
Wide Range ◽  
Compression Cycle ◽  
Cycle Systems ◽  
Component Models ◽  
And Control

Vapor Compression cycle Systems (VCSs) are being considered for thermal management aboard modern aircraft where dynamic changes in heat loads are very common. Predicting dynamic behavior of VCSs is critical to design, sizing, and control of aircraft thermal management systems. A novel Lagrangian method to model the dynamic behavior of VCSs has been developed. This approach divides each fluid flow into a large number of elements having fixed mass, but variable volume and position. At discrete time steps, heat transferred to or from each mass element is determined by component models. This paper gives simulation results showing system startup under PID feedback control. Then, from steady state, the system response to an increase in heat load, an increase in sink availability, a decrease in valve throttle and an increase in compressor speed are simulated and the results reported. Results indicate that the Lagrangian method can provide results for a wide range of cases and that VCC systems require extensive control to meet performance objectives.

Thermodynamics-Based Optimization and Control of Vapor-Compression Cycle Operation: Control Synthesis

2011 ◽  
Author(s):  
Neera Jain ◽  
Andrew G. Alleyne
Keyword(s):  
Fluid Dynamic ◽  
Control Synthesis ◽  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Optimization And Control ◽  
Operation Control ◽  
Thermodynamic Variables ◽  
And Control ◽  
Control Methodology

This paper considers the implementation of an exergy-based multiple degree of freedom (MDOF) optimization and control methodology for the operation of VCC systems. The optimization problem for the standard VCC is characterized in terms of 4 thermodynamic variables and 1 fluid-dynamic variable. The resulting control problem is then analyzed, and a design variable, Λ, is introduced which allows the user to choose how the optimization variables are projected onto a control space of lower dimension. The potential of this approach to improve operational efficiency, with respect to both first and second law efficiency metrics, is demonstrated on an experimental VCC system through implementation of the proposed optimization using a feedforward plus feedback control architecture.

A Simulink Pathway for Model-Based Control of Vapor Compression Cycles

2015 ◽  
Author(s):  
Anhtuan D. Ngo ◽  
Joshua R. Cory ◽  
Brandon M. Hencey ◽  
Soumya S. Patnaik
Keyword(s):  
Control Design ◽  
Control Synthesis ◽  
Vapor Compression ◽  
Linear Quadratic ◽  
Model Based Control ◽  
Model Based ◽  
Cycle System ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Transient Thermal

Current and next generation tactical aircraft face daunting thermal challenges that involve reliably maintaining thermal constraints despite large transient loads. Model-based control synthesis has the potential to improve the performance of a vapor compression cycle system during its transient operating condition, driven by intermittent and dynamic thermal loads, when compared to the current heuristic control design technique. However, the excessive labor and expertise necessary to develop models amenable to model-based control design techniques has been an impediment to widespread deployment. This paper demonstrates a Simulink pathway for model-based design via the AFRL Transient Thermal Modeling and Optimization (ATTMO) toolbox. An effective, simple linear quadratic gaussian control design is demonstrated and opens the door for widespread deployment of many advanced control techniques.

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