|Politecnico di Torino|
|Academic Year 2017/18|
|06IHQMN, 05IHQLX, 06IHQLN
Applied thermodynamics and heat transfer
1st degree and Bachelor-level of the Bologna process in Mechanical Engineering - Torino
1st degree and Bachelor-level of the Bologna process in Electrical Engineering - Torino
1st degree and Bachelor-level of the Bologna process in Automotive Engineering - Torino
The course is organized in two parts, each of which will be analysed before the methods and general aspects, and then applications.
In the first part, students are guided to understand as a thermodynamic systems and its control surface is linked to the surroundings thank to exchange of heat and work. The basic concepts, definitions, phenomenological laws and principles will be introduced with their mathematical representations. Subsequently the main technologies for the conversion of heat into work and vice versa will be described as well as some methods of calculation will be analysed, in particular will be considered engines and refrigeration equipment (both gas cycles and vapour cycles will be dealt with).
In the second part will be analysed, from the phenomenological point of view, the mechanisms by which the heat could be transferred in space and time: heat conduction, convection and radiation. Among the key applications will be studied heat exchangers and heat transfer in extended surfaces such as fins.
Expected learning outcomes
Knowledge of the principles of thermodynamics;
Knowledge of the main processes and thermodynamic cycles
Knowledge of the fundamentals of heat transfer, also with reference to the motion of fluids;
Ability to apply the principles of thermodynamics to simple systems;
Ability to describe and understand the main thermodynamic cycles;
Ability to read thermodynamic diagrams
Ability to identify the mechanisms of heat transfer relevant to a given phenomenon.
Ability to analyse the heat exchanger behaviour and to make a first sizing.
Prerequisites / Assumed knowledge
Mathematical analysis (differential and integral calculus, methods of solution of the simplest types of ordinary differential equations and partial differential, matrix algebra), physics (mechanics, dynamics, statics of fluids, electromagnetism, the physics of matter), and basic chemical.
DEFINITIONS AND PRINCIPLES OF THERMODYNAMICS (27 HOURS)
Purpose of Thermodynamics. Basic definitions: primitive and derived quantities. Thermodynamic coordinates, state and equations of state. Processes and transformations. Direct and inverse processes and cycles. Temperature: definition and outline of thermometry. Quantities function of process: Heat and heat flow. Work and power. Forces on surface, mass and internal forces. The equation of mechanical energy. Calorimetry: Transformations of simple homogeneous fluids. The adiabatic process. Application to ideal gases.
The First Law of Thermodynamics: Statement. Internal energy and enthalpy. The generalized enthalpy. The Second Law of Thermodynamics: Heat engines and efficiency. The irreversibility. The key statement in the form of Plank inequality. The cycle and Carnot's theorem. The Clapeyron equation. Reversible processes. Entropy. Maximum efficiency of a cycle. The theorem for maximum efficiency and maximum work. The first law for open systems. The second law for open systems. Open systems: Lagrangian and Eulerian description. The mass flow rate. Conservation of mass and momentum, first and second law of thermodynamics. The Bernoulli equation.
DIRECT AND INVERSE CYCLES (18 HOURS)
Gas cycles: ideal cycles Carnot, Otto, Diesel, Joule.
The multi-phase systems: The state changes and transformations vapor-liquid. Definitions and basic equations. The Clapeyron equation.
Steam Engines: The thermodynamic steam cycles Carnot and Rankine-Hirn, and their representations in the plans p-v, T-s and h-s. The efficiency of the Rankine cycle. Overheating and regeneration. Real gases: equation of state.
Chillers and heat pumps: Fluid friction and Joule-Thomson effect in lamination isoenthalpic. The inverse cycles. Definitions. The efficiency or COP. The h-log p diagram. Cycles of compression refrigeration machines with simple compression and multistage.
PSYCHROMETRY (6 HOURS)
ideal mixtures of ideal gases, psychrometric variables, Mollier diagram of moist air, moist air changes.
HEAT TRANSFER FUNDAMENTALS CONDUCTION, CONVECTION, RADIATION (19 HOURS)
Introduction to heat transfer. Continuous and discrete representations. The modes of the heat exchange.
Conduction: The fundamental equation with boundary conditions. The Fourier equation. Phenomenology and thermal conductivity. Applications.
Fluid flow and convection: Viscosity. Laminar and turbulent flow and Reynolds number. Interactions fluid-wall, boundary layer of speed and temperature in flat plates and in the ducts. The convection and the Newton equation. The dimensionless numbers. Forced convection in the flatbed. The heat exchange into ducts. Dimensionless relations for forced convection. Natural convection and dimensionless relations in the flatbed.
Radiation: Definitions and characteristics variables. The black body. The Stefan-Boltzmann and Wien laws. The real bodies and Kirchhoff's laws. Exchange of radiant energy between black bodies. The form factors. The electrical analogy.
HEAT TRANSFER APPLICATIONS: HEAT EXCHANGERS, EXTENDED SURFACES (10 HOURS)
Heat Exchangers: Classification and structural characteristics. Calculation of surface heat exchangers. Energy balance and heat fluxes. Trend of the temperature of the fluids in the heat exchangers in coaxial tubes. Efficiency.
Critical radius of insulation Lumped capacitance method
Heat transfer from extended surfaces.
Tutorials with problem solving examples about all the topics of the course.
Some home assignments, with a report each, to be discussed in the oral exam:
Joule cycle (gas cycle)
Vapour-compression refrigeration system
Heat exchanger analysis
The analysis concerned the Vapour-compression refrigeration system and the heat exchanger are matched to laboratory experiences.
The laboratory is located in the Energy Department at the Polytechnic of Turin (Corso Duca degli Abruzzi, 24).
Texts, readings, handouts and other learning resources
The only reference of the topics covered in the course and that will be considered is the program above.
For the purpose of adequate preparation is NOT sufficient to study only on notes taken during the lectures. To better understand the topics it is necessary to deepen the study of a book, or better, on more than one, at the discretion of the student that can be chosen from one of those listed in the list below.
Textbooks on Applied Thermodynamics only
M. Calμ, P. Gregorio, "Termodinamica" Esculapio, Bologna (the closest to the program of the course).
M. W. Zemansky, M.M. Abbott, H.C. Van Ness, "Fondamenti di termodinamica per ingegneri", Zanichelli
P. S. Schmidt, O. A. Ezekoye, J. R. Howell, D. K. Baker, "Thermodynamics: An Integrated Learning System", J. Wiley & Sons, Inc., 2006. (Good textbook in English)
Textbooks on Heat Transfer only
G. Guglielmini, C. Pisoni, "Introduzione alla trasmissione del calore", Casa Editrice Ambrosiana.
Bonacina C., Cavallini A., Mattarolo L., "Trasmissione del calore", Cleup Ed., Padova
Textbooks on both Applied Thermodynamics and Heat Transfer
Y. A. Ηengel, "Termodinamica e trasmissione del calore", McGraw-Hill.
M. J. Moran, H. N. Shapiro, B. R. Munson, D. P. DeWitt, "Introduction to Thermal Systems Engineering,
V. Giaretto, "Lezioni di Termodinamica Applicata e Trasmissione del Calore", edizioni CLUT
Exercises on both Applied Thermodynamics and Heat Transfer
P. Gregorio, , "Esercizi Svolti (4 volumi)", Levrotto & Bella Ed., (Excellent text of guided exercises).
Assessment and grading criteria
The examination consists of: HOME ASSIGNMENTS (mandatory), a WRITTEN EXAMINATION (mandatory) and ORAL EXAMINATION (not mandatory if the previous parts are sufficient, see rules below).
The Home Assignments must be made and then uploaded as a file (PDF) on the webportal of the course 3 days before the writing examination.
The access to the written examination is allowed only for the students who have complied with the requirements on the reports described above.
The written examination consists of four questions: 2 calculation exercises, and 2 open-ended questions.
The exercises require you to explain in writing the analytical steps and the numerical solution, up to the numeric final results accompanied by the correct units. The exercises may also require the use of charts and tables that will be provided during the exam. The maximum score for the exercises is 14 points.
The open-ended questions will deal with all the arguments developed in the lectures and in the home assignments. The maximum score for the open-ended questions is 14 points.
You can have access to the oral examination only if in the written examination the following scores are achieved simultaneously:
▪ at least 8 points for the exercises
▪ at least 8 points for the open-ended questions
If these values are not reached, the student has to repeat the written exam in another call.
After the correction of the written examination you can be in the following cases:
(I) Students with score between 18 and 28 (included) can choose to:
-A- Accept the score of the written exam (which will be registered)
-B- Do an oral examination (which will include all the topics of the lectures, and the reports as well). The oral examination score falls inside the range plus or minus 8 points, therefore the final mark can either increase or decrease, and if you have serious gaps, and final score under 18, you are rejected.
-C- Refuse the written exam and repeat the written test in another call of the exams.
(II) Students with score between 16 and 17 (included) can reach the sufficiency only with an oral exam (which will include all the topics of the lectures, and the home assignments as well). Who is not sufficient during the oral exam will be rejected and will have to repeat the written examination in another official data.
All those who make the oral examination will have to bring a complete printing of the Home Assignments (those uploaded on the webportal before the written exam) needed for the discussion of the reports.
Programma definitivo per l'A.A.2017/18