B2373 - Machines and Sustainable Energy Systems

Learning outcomes

The student is able to face the design of modern energy systems (combined groups, cogeneration groups) for the production of electricity and refrigeration cycles (compression, absorption, air). He is also able to deal with the fluid-dynamic design of the compressible turbomachines. Finally, the student acquires the basic knowledge on systems for the production of electricity and heat from renewable sources.

Course contents

ENERGY SISTEMS

-WORLD energy panorama

-COMBINED CYCLE POWER PLANTS (CCPP) or GAS-STEAM CYCLES: Overall performance, 1 pressure level without and with reheating, 2 pressure levels, optimization of the flow rate spilled from the low-pressure liquid separator (steam drum), 3 pressure levels (lay-out only), T-S diagram and heat exchange diagram T-q

-COGENERATION: POWER AND ENERGY EVALUATION INDEXES, Cogeneration: gas turbine, with back pressure steam turbine and with condensing steam turbine. Cogeneration in Combined Cyle Power Plant.

-WIND ENERGY: Betz – Lancaster limit

-SOLAR ENERGY: Thermal (production of hot water for sanitary purposes). Photovoltaic: production of electricity through the use of semiconductors. Thermodynamic: thermal energy is used to evaporate oils/salts, which then expand in a turbine producing electricity.

-GEOTHERMAL ENERGY: Hydrothermal plants. Dominant water cycle: Ambient discharge, Condensation. Dominant steam cyle: Flash steam cycle, Binary cycle. HYBRID geothermal cycles: Gas turbine systems, Steam power systems with spilled steam.

-FUEL CELLS: Introduction, Working principle, PEM

Hydrogen: Energy vector, Properties, Storage. Production: types of hydrogen. Comparison versus methane.

 

FLUID MACHINES

-Isentropic and polytropic compression and expansion efficiencies -FLUID MACHINES:

-Definition

-Classification

-TURBO-MACHINES

-RADIAL flow

-AXIAL flow

-MIXED flow

-STAGE of a TURBO-MACHINE

-NAVIER-STOKES equations for the study of the flow and simplifications

-Fundamental equations for turbo-machines: Perfect gas, Real gas, State functions, Thermodynamic transformations.

-MASS CONSERVATION PRINCIPLE

-ENERGY CONSERVATION PRINCIPLE:  CLOSED system, OPEN system

-WORK ACCORDING TO EULER IN TURBOMACHINES

-DIRECT formulation: FIXED and MOBILE (RELATIVE) observer, Potential (gravitational, centrifugal) and Potential Energy, Rothalpy

-INDIRECT formulation or WORK to the DIFFERENCE of KINETIC ENERGIES

-GAS DYNAMIC

-MACH number

-Coupling of equations of motion (mass, energy, momentum)

-1D COMPRESSIBLE MOTION IN THE DUCT

-PROPAGATION OF ACOUSTIC WAVES

-Speed of SOUND

-ISENTROPIC FLOW IN A CONSTANT SECTION DUCT: PARAMETRIZATION OF THE EQUATIONS AS A FUNCTION OF THE MACH NUMBER

-TOTAL quantities

-ISENTROPIC FLOW IN A VARIABLE SECTION DUCT: Nozzle and Diffuser

-SOLUTION OF THE ISOENTROPIC FLOW IN A PURELY CONVERGENT DUCT

-CHOKING

-DE LAVAL nozzle (CONVERGENT-DIVERGENT)

-OPERATING MACHINES (COMPRESSORS)

-COMPRESSORS: VOLUMETRIC; TURBO-COMPRESSORS (STAGE=ROTOR + STATOR):

- AXIAL

- CENTRIFUGAL

- COMPARISON BETWEEN AXIAL AND CENTRIFUGAL COMPRESSOR

- DIAGRAMS: h-s for rotor, stator, compression stage

- PERFORMANCE PARAMETERS: TOTAL to TOTAL efficiency; TOTAL to STATIC efficiency; STATIC to STATIC efficiency.

-GEOMETRICAL TOPICS: MERIDIAN component of velocity

-CENTRIFUGAL COMPRESSOR: Backward blades (negative), forward blades (positive), straight blades (radial), Rotor blade lower surface (or blade pressure face – ventre) and rotor blade upper surface (blade back - dorso): pressure trend as a function of the radius qSTALL; PUMPING; Degree of REACTION; Blade loading (blade stress); Rotor; SLIP FACTOR: EMPIRICAL formulation by STANITZ; DIFFUSERS With blades and Without blades

-AXIAL COMPRESSOR: Degree of REACTION; Symmetrical blades

-VOLUMETRIC COMPRESSOR: Reciprocating compressor (Ideal cycle, Real cycle); Rotating compressor (ROOTS); Sliding vane compressor

-DRIVING MACHINES (TURBINES)

-Introduction

-Thermal turbines: Axial-flow turbine, Inward-flow turbine (centripetal or radial), Stage of turbine, Performance parameters 

-INWARD-FLOW TURBINE: Diagram h-s; TOTAL to TOTAL, TOTAL to STATIC, STATIC to STATIC efficiencies; Performance curves; Force fluid flow - blade; Degree of REACTION

-AXIAL-FLOW TURBINE: Rothalpy; Degree of REACTION; Efficiency; Minimum kinetic energy at the discharge; Simplified calculation of a stage; IMPULSE turbine (ACTION): DE LAVAL turbine, Rotor with symmetric blades, Rotor with non-symmetric blades, Real case

REACTION turbine: Ideal case, Optimized case, Comparison bewteen REACTION stage and IMPULSE stage

-RADIAL INWARD-FLOW TURBINE: Some considerations on applications for ICEs

Readings/Bibliography

"Sistemi Energetici e Macchine a Fluido" Vol. 1 (Macchine a Fluido) e 2 (Complementi), G. Negri di Montenegro, M. Bianchi, A. Peretto

Pitagora Editore.

"Fundamentals Of Renewable Energy Processes" – Aldo Vieira Da Rosa, Juan Carlos Ordonez, Academic Press – ISBN 978-0-12-816036-7

"Advanced Power Generation Systems ", Ibrahim Dincer and Calin Zamfirescu, Elsevier

"Sustainable Power Generation (Current Status, Future Challenges, and Perspectives)", Nikolay Belyakov, Academic Press

"Gas-Turbine Power Generation" - 1st Edition - February 24, 2016 - Paul Breeze - ISBN: 9780128040058

"Macchine a Fluido" DOSSENA V.; FERRARI G.; GAETANI P.; MONTENEGRO G.; ONORATI A.; PERSICO G.

HOEPLI Editore

"Turbomachinery Flow Physics and Dynamic Performance" Meinhard T. Schobeiri – Springer – 2nd edition

"Gas Turbine Theory" - H.I.H. Saravanamuttoo, G.F.C. Rogers, H. Cohen, Paul Straznicky, A. C. Nix - Ed. Pearson

"Fluid Mechanics and Thermodynamics of Turbomachinery", Dixon S.L., Hall C., Ed. Butterworth-Heinemann

"Principles of turbomachinery in air breathing engines", E.A. Baskharone, Cambridge University press

Teaching methods

PLATFORM ‘VIRTUALE’ (https://virtuale.unibo.it/): Lectures and/or presentations uploaded at the end of the lesson.

IT IS STRONGLY RECOMMENDED TO ALWAYS CONSULT THE BOOKS LISTED BEFORE.

The lessons are frontal in the classroom. The teacher, replacing the traditional blackboard, uses a tablet connected to the projector to develop the concepts and to show the supporting teaching material. At the end of the lesson the teacher makes available the material shown in a pdf file, downloadable from platform VIRTUALE. ALL forms of distribution of this material are FORBIDDEN: every ENROLLED STUDENT can download it in AUTONOMY. This material is NOT intended as a DISPENSE but is ONLY a study support system. The teacher DOES NOT provide any DISPENSE, but INVITES the students to use the TEXT BOOKS.

Attendance is strongly recommended for better learning of concepts and notions, but does not affect the final evaluation process.

Assessment methods

The assessment methods consist of an oral part lasting about 30 minutes, during which the student must answer one question for energetic systems and one for fluid machines: the questions are extracted from the entire program.

During the exam, with regard to fluid machines, their components and functions, is evaluated the student's ability to:

- use the thermodynamic instruments correctly;

- describe their operation;

- theoretically justify their architecture;

- represent their geometry with a free hand sketch;

- evaluate their performance;

The final quote, expressed in thirtieths, will be higher the more the student is:

- autonomous in articulating responses to the two questions;

- exhaustive in explaining the arguments;

- precise in representing the functionality of the free-hand sketches.

The exam dates are comunicated in advance through the AlmaEsami web platform of the University of Bologna. It is possible to enroll to the exam upto 3 days before the exam date. At the time of the exam the student must carry an identification document.

Teaching tools

The course will be carried out through the use of:

- Tablet connected to the projector, used as an alternative to the blackboard.
- Each lesson will be uploaded on the VIRTUALE platform, as an aid to the students.

Office hours

See the website of Stefania Falfari