Heat transfer in food industry processes
cod. 1008528

Academic year 2022/23
1° year of course - Second semester
Professor
CATTANI Luca
Academic discipline
Fisica tecnica industriale (ING-IND/10)
Field
Attività formative affini o integrative
Type of training activity
Related/supplementary
48 hours
of face-to-face activities
6 credits
hub:
course unit
in ITALIAN

Learning objectives

- Knowledge and understanding:
At the end of the course the student will learn the theoretical principles of energy processes applied to the food industry. The student will therefore have to possess knowledge related to the heat transfer phenomena with reference to conduction, radiation and convection even in the presence of complex rheology fluids.

- Applying knowledge and understanding:
The student will acquire applicative knowledge, in relation to transport processes in the food industry field and will acquire the basic tools to deal with autonomy and critical sense the choices that support the sizing of heat transfer equipment.

- Making judgments:
By the end of the course the student will have the tools to critically evaluate the energy processes that occur in the food industry.

- Communication skills:
Through the frontal lessons and the assistance of the teacher, the student acquires the specific vocabulary inherent to energy processes. The student must possess the ability to clearly present the procedure
adopted in the evaluation of transport processes in the food industry.

- Learning skills:
The student who has attended the course will be able to deepen his knowledge in the field of energetics in the food transformation industry through the autonomous consultation of specialized books, scientific journals, even outside the topics explained during lectures also in view of the entrance in a job environment or in a third level course.

Prerequisites

To follow the course with profit requires knowledge of the basic concepts of Applied Physics

Course unit content

The course aims to provide the students with basic and applicative knowledge on energy processes of the food industry. During the course theoretical lessons are coupled to exercise activity. The theory lectures cover the following subjects: Heat Transfer Mechanisms. Steady and unsteady heat conduction. Mass Transport. Convective heat transfer. Analogy between the transport of energy, mass and momentum. Convective heat transfer enhancement. Heat exchangers. Rheology and non-Newtonian fluids.
The practical lessons are integral part of the course and they are dedicated to exercises that provide the opportunity to apply the skills and knowledge acquired in the course.

Full programme

Heat Transfer mechanisms.
Energy equation and its dimensionless form. Dimensionless numbers and Buckingham theorem.
Steady-state and unsteady heat conduction. Non dimensional form of the Fourier equation and of its boundary conditions: Fourier number, Biot number; limiting cases for large and small Biot; Semi-infinite solids. Convection:
Principles of convection. External flow. Internal flow. Hydrodynamic and thermal considerations. The energy balance: constant surface heat flux and constant surface temperature. Laminar flow in circular tubes. Convection correlations.
Mass transfer:
Fick's law. Mass diffusion coefficient.
Analogy between momentum, energy and mass transfer.
Heat transfer enhancement
Principles of enhanced heat transfer. The enhancement techniques. Passive techniques. Active techniques. Benefits of enhancement. Plate and fin extended surfaces. Externally finned tubes. Insert devices for
single-phase flow. Internally finned tubes and annuli. Integral roughness.
Heat Exchangers:
Heat exchanger types. The overall heat transfer coefficient. Heat exchanger analysis. The log mean temperature difference method. The parallel and counter flow heat exchanger. Multipass and cross flow heat
exchangers. The effectiveness NTU method.
Rheology:
General concepts of rheology. Generalized treatment of Non-Newtonian fluids. Non-Newtonian models: Bingham, shear thickening, shear thinning, power law. Rheological measurement. The capillary tube rheometer and the rotational viscometer. Laminar fully developed velocity profile of a power law fluid within a circular tube. Generalized Reynolds number. Turbulent flow regime. Dodge and Metzner correlation. Convective heat transfer to power law fluids. Ohmic and microwave heating, introduction to unconventional treatment techniques

Bibliography

The notes of the lectures and exercises, and all the supporting material are available to students and shared on Elly platform. In addition to the shared material, the student can personally study some of the topics discussed during the course in the following books:F. P. INCOPRERA, D P DE WITT: " Fundamentals of Heat and Mass Transfer ", John Wiley & Sons, New York.
S. Yannotis: Solving Problems in Food Engineering - Springer
- Berk, Z. (2018). Food process engineering and technology. Academic press.
- Sun, D. W. (2005). Thermal food processing: new technologies and quality issues. Crc Press.
- Toledo, R. T., Singh, R. K., & Kong, F. (2007). Fundamentals of food process engineering (Vol. 297). New York: Springer.
- Singh, R. P., & Heldman, D. R. (2001). Introduction to food engineering. Gulf Professional Publishing.

Teaching methods

The course counts 6 CFUs (one CFU, University Credits equals one ECTS credit and represents the workload of a student during educational activities aimed at passing the exams), which corresponds to 48 hours of lectures. The teaching activity will be mainly organized in frontal lessons and practical exercises. During the frontal lessons the theoretical topics of the subject will be dealt with the aim of promoting the understanding and assimilation of the concepts at the base of the course. In the exercises, the concepts illustrated in the frontal lessons will be applied in practice, tackling problems of the food industry.

Assessment methods and criteria

The exam is based on a written test requiring the answer to 10 questions regarding both exercises and theory questions. The results of the written test is communicated within a few days after the test itself, through publication on Esse3 Platform. The final vote, that considers the vote of the written test is normalized in a scale in thirtieths. The Laude is added in case of excellent score in each item.
Please note that online registration is compulsory for the written test.

Other information

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