Ingegneria Energetica - Energy Engineering

Richiami di base e unità di misura, conversione, richiami di termodinamica, proprietà termofisiche e del trasporto, numeri adimensionali, conduzione, conduzione in regime permanente, conduzione in regime transitorio, equazioni di conservazione: massa, quantità di moto ed energia, scambio termico per radiazione, convezione e strato limite, flusso esterno ed interno in convezione forzata, regime turbolento, convezione naturale, scambiatori di calore, flussi bifase: grandezze caratteristiche e proprietà, regimi di deflusso bifase, ebollizione - generalità, pool boiling, ebollizione sottoraffreddata e in saturazione, flusso termico critico e crisi termica, condensazione, teoria di Nusselt.

E' richiesta una conoscenza di base della termodinamica e dello scambio termico come presentato in Fisica Tecnica - 1022052.

Fundamentals of Heat and Mass Transfer, 7th Edition, by T.L. Bergman, A.S Lavine, F.P. Incropera and S. P. Dewitt. John Wiley and Sons, 2011 Convective Boiling and Condensation, 3rd Ed., by J.G. Collier and J.R. Thome. Oxford University Press, 1994. Dispense fornite dal docente

Lezioni ed esercitazioni sono svolte in presenza con lezioni frontali.

La frequenza non è obbligatoria, ma caldamente consigliata. L'interazione con il docente durante la lezione è incoraggiata.

The student will be evaluated during the semester and at the end of the course by a written test (compulsory) and an oral one (facultative, depending on conditions). Minimum passing grade is 18/30, which is equivalent to achieving 36 points. Semester evaluations During the semester, student progress is evaluated using questionnaires and lab activities. To ensure a proper monitoring, the participation to some of these activities is compulsory. Performance in the semester evaluation can be valid to determine part of its final grade up to a maximum of 25 points, following the guidelines reported below. Three kinds of semester evaluations are foreseen: • Self-Evaluation tests (SET): these multiple choice and short exercise tests are distributed through the course website and are representative of the questions you could face during the written examination. They are dedicated to a single topic and are going to be released according to the course schedule. They will stay available throughout the semester (and afterwards) for practice. A limited number of attempts (5) is possible for each test. Please note that passing SET-0 (Fundamental concepts) is compulsory to attend the written examination. • Progress Evaluation Tests (PET): these multiple-choice tests are distributed through the course website. Participation to all PETs is compulsory. They are going to be available only for a limited time, which will be disclosed by the teacher, typically one week after the last lesson on the relevant topic. Only one (1) attempt is possible for each test. o Single-phase heat transfer (conduction/convection) and heat exchanger PET (PET-1Phase): average grade can be converted into bonus points (up to a maximum of 10 and only above a minimum threshold). Result is going to be communicated at the end of the semester and the student may elect to use these bonus points to substitute the multiple-choice questionnaire during the written exam. This can be done only for the first three exam sessions, 2 ordinary and 1 extraordinary (until March). o Two-phase flow and phase change PET (PET-2Phase): average grade is converted into bonus points (up to a maximum of 10 and only above a minimum threshold). Result is going to be communicated at the end of the semester and used to calculate the preliminary grade after the written exam. This can be done only for the first three exam sessions, 2 ordinary and 1 extraordinary (until March). • Laboratory practise session (LPS): a short experimental experience performed in the teaching thermal-hydraulic lab at Palazzo Baleani. A group of maximum two (2) students will gather experimental data and write a short report describing the experiment performed and perform some basic calculations using these data. The report is going to be graded and will award up to 5 bonus points. Result is going to be used to calculate the preliminary grade after the written exam. Lab session schedule is going to be communicated by the teacher and will be limited to the period December-March. Written exam The written test is intended to evaluate the student preparation on the topics of single-phase heat transfer and heat exchangers (Unit 1 to 13). To attempt the test, the student must have passed the SET-0. The test will last 150 minutes (2.5 hours) and will consist of: 1. A multiple-choice questionnaire of 20 questions on all topics considered for the test, up to 10 points (which can be substituted by the average PET grade if certain conditions are met). 2. Three numerical exercises, one (1) short question and two (2) longer problems, up to 15 points. a. Long problems are like those presented in the exercise sessions, both those where I show you the solution procedure and those with just the answer. b. Short problems are typically much simpler and require one or two calculations to be solved. Some are discussed during regular lectures (look in the lesson notes). 3. Two short-essay style open questions on theoretical topics, up to 16 points. a. Examples of open questions can be found in the Syllabus within the folder “Written test examples” Minimum passing grade is 24 points out of the 41 available in the test. Examples of past exam question sheets can be found in the Syllabus within the folder “Written test examples” Preliminary grade Once the written test has been completed, points achieved there will be summed to those accumulated during the semester evaluation. A preliminary grade will be calculated according to the formula: (Total points of written examination + lab activity + PET two-phase flow)/2. If the preliminary grade is >= 18 (36 points), the student may elect to transform it into its final grade. If your preliminary grade is <18, you must attend the oral examination. To improve the preliminary grade, the student must attend the oral examination. • Example/1: Andrea passed their written test with 24/40 (minimum score) and has 5 points from LPS and 0 points from PET-2Phase. Their preliminary grade is (24 +5 + 0)/2 = 29/2 = 14.5. Andrea must attend the oral examination to achieve a passing grade. • Example/2: Jessie passed their written test with 33/40 and has 3 points from LPS and 8 points from PET-2Phase. Their preliminary grade is (33 +3 + 8)/2 = 44/2 = 22. Jessie can transform their preliminary grade. Their final grade would be 22/30. Jessie can elect to attempt the oral examination to get a better grade. Preliminary grade can be kept between two exam sessions belonging to the same exam period: for instance, a preliminary grade obtained in January can be improved in the oral examination of February, but not in the one of June. Oral examination The oral examination is composed of either 1 or 2 questions pertaining the topics of two-phase flows (basic concepts, pool boiling, flow regimes and flow boiling, condensation) and can award up to 20 points (possibly including up to 10 points from two-phase flow PET). Examples of exam questions can be found in the Syllabus within “Oral test examples”. Depending on the semester evaluation: • If the student PET is still valid, this will be valid for 50% of the oral examination grade. The exam will consist of one (1) question (Reduced Oral) that will award the remaining 50%, from 0 to 10 points. o At the beginning of the oral examination, the student may elect to discard the PET grade. • If the student PET is no longer valid or has been discarded, the exam will be composed of two (2) questions (Full Oral), that may award between 0 and 20 points. Please note that a passing grade (6/10 and above for reduced oral or 12/20 and above for full oral) is still required to pass the oral examination, regardless of the preliminary grade. If the performance during the oral examination is deemed to be gravely insufficient by the teacher, the oral examination is failed. The written exam grade will be maintained for a second attempt at oral examination in a successive exam session (please note that the rules for PET score validity applies in this case). If the second attempt also fails, the written exam grade is voided and the student has to attend another written examination. Explicative scenarios: • Example/1: Andrea has a preliminary grade of 32 points, of which 5 from the PET-2Phase. If they choose to discard the PET, the maximum grade they can achieve (with two questions) is: [(Preliminary grade – PET-2Phase)+Max Full Oral Score]/2 = [(32-5)+20]/2 = 47/2 = 24. If they choose to keep the PET score, the maximum grade they can achieve with one question is: (Preliminary grade + Max Reduced Oral Score)/2 = (32 + 10)/2 = 42/2 = 21. • Example/2: Jessie has a preliminary grade of 44 points, of which 8 from the PET-2Phase. If they choose to discard the PET, the maximum grade they can achieve (with two questions) is: [(Preliminary grade – PET-2Phase)+Max Full Oral Score]/2 = [(44-8)+20]/2 = 56/2 = 28. If they choose to keep the PET score, the maximum grade they can achieve with one question is: (Preliminary grade + Max Reduced Oral Score)/2 = (44 + 10)/2 = 54/2 = 27. Final grade Final grade will be calculated according to the formula: (Preliminary grade + oral examination grade)/2. The minimum passing grade is 18 (equivalent to 36 points). If the total number of points is above 60, the student will be awarded the course honors.

A Heat Transfer Textbook, 5th ed, John H. Lienhard - Disponibile qui: https://ahtt.mit.edu/

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