OVERVIEW

The aim of the teaching is to provide the skills for the choice, sizing and calculation of the performance of numerous types of heat exchange organs present in industrial and civil systems and plants.

AIMS AND CONTENT

LEARNING OUTCOMES

The aim of the teaching is to provide the skills for the choice, sizing and calculation of the performance of numerous types of heat exchange components for industrial and civil systems and plants.

AIMS AND LEARNING OUTCOMES

At the end of the course the student will have acquired the skills for the choice, sizing and calculation of the performance of numerous types of heat exchange organs present in industrial and civil systems and plants. In addition to theoretical notions of analysis and modeling, the student will have acquired a technical background that will allow him to try his hand at designing heat exchange systems and optimizing the performance of heat exchangers in complex systems.

These objectives will be achieved with theoretical lessons combined with numerical applications carried out during the exercises, as well as through seminars and educational visits to heat exchanger manufacturers, aimed at the industrial engineering training of the student.

PREREQUISITES

There are no prerequisites for accessing the final exam.

TEACHING METHODS

Lectures and exercises also with the help of a PC.

The didactic innovation project adopted by the Degree Course in Mechanical Engineering, innovative tools will be used for active student learning. The aim is to increase students' skills through new learning methodologies, from e-learning to team work, through experiences that increase student participation through a higher communicative level and make the student more aware and autonomous.

Students who have valid certification of physical or learning disabilities on file with the University and who wish to discuss possible accommodations or other circumstances regarding lectures, coursework and exams, should speak both with the instructor and with Professor Federico Scarpa (federico.scarpa@unige.it), the Polytechnic School's disability liaison.

SYLLABUS/CONTENT

Classification of heat exchangers; equitable and counter-current exchangers: calculation of the logarithmic mean temperature difference and of the transmittance. Efficiency and friction factor; correlations of heat exchange, wall temperature.

Cross-current exchangers: temperature distribution and heat exchange; heat exchange correlations for single pipes and bundles of pipes; calculation of head losses; finned surfaces: fin and fin efficiency.

Tube bundle exchangers: actual logarithmic mean temperature difference, determination of the Ft factor, longitudinal and transverse diaphragms. Calculation of the exchange coefficient using the Kern method; calculation of head losses; parts of an exchanger and methods for limiting differential voltages; Performance calculation and sizing; calculation procedures.

Compact exchangers: geometric parameters; definition of the average temperature of the fluids; calculation of head losses. Performance calculation. Number of thermal units of individual fluids as a function of the global NTU; correlation with the pressure drops along the exchanger; determination of the specific flow rate of the first attempt. Sizing through the calculation of the specific flow rate of the first attempt.

Plate exchangers: types and applications, geometric parameters; problem of the misdistribution of two-phase fluids.

Notes on the phenomenon of fouling.

Fundamentals of mass transfer; conservation equation of chemical species, Fick's law, diffusion coefficient. Equimolar counter-diffusion and diffusion through a stagnant film. Mass transfer coefficients; relationship between the heat transfer coefficients and mass. Wet bulb temperature and adiabatic saturation temperature.

Evaporative towers: classification, filling materials; replenishment scope; analysis of the exchange mechanisms, calculation of the NUD. Characteristic curve of the tower, calculation of the air outlet conditions, sizing; influence of process conditions. Numerical exercise.

Condensation of vapor mixtures: Influence of non-condensables on interface resistance; Calculation of a mixture of a condensing vapor.

Evaporative condensers: general information; Mollier diagram; non-adiabatic evaporation; graphic evaluation of the heat exchange contributions; calculation of an evaporative condenser; determination of the air and water outlet conditions.

Regenerators: analysis of thermal accumulation, fixed and rotary bed regenerators, regenerators for high and medium-low temperatures; differential equations for the fluid and for the solid matrix.

Theory of regenerators: dimensionlessization of independent variables and temperatures; fair and counter-current efficiency. Longitudinal conduction; heat resistance; pressure difference; residence time. Calculation of the performance of a rotary regenerator.

RECOMMENDED READING/BIBLIOGRAPHY

•             Termodinamica e trasmissione del calore. Y. A. Cengel; McGraw-Hill; ISBN 8838662037.

•             Heat Exchangers: Selection, Rating, and Thermal Design, Third Edition. Sadik Kakaç and Hongtan Liu; CRC Press; 3.ed 2012; ISBN 9781439849903.

•             Fundamentals of Heat Exchanger Design. Sekulic, Dusan P.; Shah, Ramesh K.; ISBN 9780471321712.

•             Heat exchangers. S. Kacaç, A.E. Bergles, F. Mayinger, Hemisphere Publishing Corporation.

•             Process heat transfer. D.Q. Kern, McGraw Hill.

•             Compact Heat Exchangers. W. M. Kays, A.L. London, Krieger Publishing Company, 1984, 3rd edition.

•             Heat transfer. A. Bejan,John Wiley & Sons, Inc.

•             Heat pipes: Theory, design and application, Edgar Miller, Willford Press, 2016

•             Design and technology of heat pipes for cooling and heat exchange, Calvin C. Silverstein, Taylor & Francis Group, 1992

•             The evaporation mechanism in the wick of copper heat pipes, Shwin-Chung Wong, Springer, 2014

•             Oscillating heat pipes,  Hongbin Ma, Springer, 2015

•             Heat Transfer Handbook, A.Bejan, A.D.Kraus, John Wiley & Sons, 2003

TEACHERS AND EXAM BOARD

Exam Board

ANNALISA MARCHITTO (President)

GUGLIELMO LOMONACO (President Substitute)

LESSONS

LESSONS START

https://corsi.unige.it/en/corsi/9270/studenti-orario

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

The exam consists of an oral interview, preceded by the delivery of the exercises and projects proposed during the course, which are the subject of discussion during the interview.

ASSESSMENT METHODS

After passing a preliminary design or written test, oral examination, based on a specific subject among those tackled during the taught course, with in addition a couple of small synthetic questions on other one/two subjects.

The aim of the examination is to assess the capability of solving specific thermal problems (including physical formulation and mathematical passages) and the skill in  discussing and arguing them.

Exam schedule