66054 - Refrigeration Systems and Safety Elements

Course Unit Page

Academic Year 2019/2020

Learning outcomes

At the end of the course the student has acquired the knowledge of the principles of operation, the dimensioning and choice of modern refrigeration systems. The student has also acquired the basic technical, legal and normative concepts on safety of the equipment.

Course contents

Phase diagrams: pressure(p)-volume(v), p-temperature(t), p-v-t. First and second principles of thermodynamics. Enthalpy(h) and entropy(s). Freezing machine. Ideal vapour compression refrigeration cycle. Standard cycle and its variations. Cycles representations in the p-h and t-s plans. Efficiency of the refrigeration cycle. Multi-stadium systems: vapour bubbles extraction and intermediate cooling. Compressors, evaporators, condensers, expansion valves: mechanical and thermodynamic aspects. Refrigerants characteristics. Structures and freezing plants for the agri-food storage "at positive temperature" and for the deep-freezing, thermal load calculation and dimensioning. Control of the atmosphere in the cooling cell.  Legal and normative framework in Europe on safety. Directive 2006/42/EC and Italian Law Decree 2010/17. Directive 89/391/EEC and Italian Law Decree 2008/81. The instrumental control of the machines: acquisition and signal processing, sensors and functional aspects of construction, signal conditioners, analog to digital converters, data processing. The ISO1999/2013: noise measurement, analysis and effects. Specificity on the safety of refrigeration systems.


W. F. Stoecker, "Manuale della refrigerazione industriale", Tecniche nuove, Milano, 2001.

Downloadable material from Internet: glossary, directives, standards, laws etc. Records from lectures.

Teaching methods

Lectures supported by whiteboard with camera, illustrative material on all the course topics, drills mainly consisting in calculation of the thermodynamic parameters for the refrigerating cycles analysis, thermal loads determination for the dimensioning of plants for "positive temperature" refrigeration and deep-freezing, finding of norms and laws on safety from Web.

Assessment methods

Final exam quiz-type with multiple choice and single answer (16 questions; duration of the test: 90 min).

See the notice in IOL for on-line exam method.

The exam is designed to assess the student learning on all the arguments covered in class. In particular, the following aspects are evaluated:

1) the theoretical and technical knowledges;

2) the ability of critical choise;

3) the ability, by numerical calculation, to determine some parameters related to the subject of study.

During the course, the teacher has also opportunity to assess the degree of attention and critical participation of the students in the lectures and exercises looking for, although it is not required, the involvement of the students in the analysis and discussion. This is useful to better modulate the teaching according to the student's answer, without which the result of this interaction can represent prejudice for the final evaluation.

The final grade is a summary of the joint evaluation of the two constituents of the teachings integrated course, based on a ponderation related to the CFU of each course.

Call dates for each session: two.

Teaching tools

Personal computers connected to Internet used by the teacher in classroom. Blackboard. Whiteboard with camera. Audio systemVideo projector. Library.  Computer room. Food engineering lab.

Office hours

See the website of Luigi Ragni