66054 - Refrigeration Systems and Safety Elements

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 ISO12100/2010: safety of machinery, design, risk assessment and reduction. 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 ISO1999/90: noise measurement, analysis and effects. Specificity on the safety of refrigeration systems.

Readings/Bibliography

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 illustrative material on thermodynamic aspects and mechanical components, drills mainly consisting in calculation of the thermodynamic parameters, dimensioning of the plants, signals acquisition and processing, finding of norms and laws on safety from Web.

Assessment methods

Final oral exam. The exam is designed to assess student learning on two or more topics covered by lessons. In particular, the following aspects are evaluated:

1) theoretical and technical knowledges;

2) the ability of critical analysis;

3) the ownership of the used scientific-technical language.

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.

Dates of appeal for each session: two.

Teaching tools

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

Office hours

See the website of Luigi Ragni