Physical processes involving fluid flow, heat transfer and thermal/mechanical power conversion are at the heart of numerous engineering systems, whose performance crucially depends on control. The main goal of the course is to provide the methodological foundations for the control-oriented dynamic modelling of such systems, enabling the students to understand what are the control-relevant dynamic phenomena, how to model them and how to use these models to design effective control strategies. Particular emphasis is put on the concept that the achievable control performance is determined by the dynamic physical behaviour of the process and on establishing links between physical process behaviour and control-relevant aspects.

The concepts are applied to a number of classical examples in the field of process control and thermal power generation, thus also providing the students an overview of typical control problems in this field and on how they can be solved effectively once the dynamic process behaviour has been clearly analyzed.

At the end of the course, the student

• knows the basic conservation equations governing thermo-mechanical-hydraulic processes, both lumped-parameter (0D) and distributed-parameters (1D)
• knows the constitutive equations of the models of specific phenomena (such as pressure losses or heat transfer) as well as of specific machinery (such as valves, turbines, compressors, etc.)
• understands the time scale of different dynamic phenomena in these processes
• is aware of how classical control problems are solved in the field of fluid processing and thermal power generation
• understands how the mechanical design parameters and the operating point of such systems influence their controllability and how it may be possible to improve the control performance also by changing these parameter (process-control co-design)

The student is able to

• estimate the time scale of different dynamic phenomena in thermo-hydraulic-mechanical processes, so as to select the ones which are relevant for control while neglecting those which are not
• derive control-oriented dynamic models of thermo-hydraulic-mechanical processes
• analyze these models and simplify them as much as possible to gain insight on the relationship between the mechanical design and operating parameters, the control design, and the achievable control performance
• interact with specialists in the area of thermo-hydraulic-mechanical process design in multi-disciplinary teams with the ultimate goal of designing better-controlled innovative systems

The student is also able to explain what are the main control problems in a number of applications in the field of fluid processing and thermal power generation and which model-based control strategies can be used to solve them.

Part 1: Introduction and fundamental equations

• Role of modelling for the design of control systems
• Detailed models for numerical simulation vs. simplified analytical models for control design
• Mass, energy and momentum balance equations for 0D systems
• Mass, energy and momentum balance equations for 1D systems
• Estimation of time scales of different phenomena in 1D systems
• Equations of state and thermodynamic properties of working fluids

Part 2: Modelling of components of thermo-hydraulic and power production processes

• Control valves and piping equipment
• Turbomachinery: pumps, compressors, turbines
• Simplified models of combustion phenomena
• Single-phase heat exchangers
• Two-phase heat exchangers and boilers
• Electrical power generation and transmission equipment

Part 3: Analysis and design of control systems

• Control of simple hydraulic circuits
• Power/frequency control in hydro power plants
• Temperature control in single-phase heat exchangers
• Control of gas turbines
• Control pressure, level and load in simple steam generators
• Control problems in coal-fired and combined-cycle power plants

A solid understanding of the design of linear SISO controllers (PID-type), basic MIMO linear control design, cascaded control, and disturbance compensation techniques. A good understanding of the performance limitations of linear controllers, particularly in the case of non-minimum-phase processes is also recommended.

Basic knowledge of technical thermodynamics: fluid properties, enthalpy and entropy, basic heat transfer (convection, radiation, conduction), basic understanding of the working principles of turbomachinery (pumps, compressors, turbines) and of power generation cycles (Brayton, Rankine).

The final learing assessment is by written exam, with optional oral discussion to change the final mark up to +/- 3 points. During the exam, the student will be asked to

• Write down appropriate conservation laws and consitutive equations for all the system components described in the course
• Evaluate the time scale of different physical phenomena in a given process and, based on that, decide what are the most appropriate modelling assumptions for a control-oriented model
• Derive simplified models of the fundamental dynamics of a given process, that can be used for control design, and use them to derive a control strategy and possibly to tune the controller parameters
• Describe and discuss the control-relevant dynamic phenomena, the control problems and the control strategies of the systems discussed during the course