Coursecode: wb4410A
Coursename: Refrigeration Fundamentals

ECTS creditpoints: 3

Faculty of Mechanical, Maritime and Materials Engineering

Lecturer(s): Infante Ferreira, dr. ir. C. A.

Tel.: 015-27 84894

Catalog data:
Refrigeration fundamentals. Ozone and global warming issues. Total Equivalent Warming Impact. Overview/comparison of refrigeration and heat pump systems. Mechanical vapour compression, gas cycle (expansion) machines, thermo-electric cooling, absorption refrigerating machines. Primary and secondary working fluids. Control. Latest developments in refrigerating technology.

Course year: MSc 1st year
Period: 1A
Hours p/w: 4
Other hours:
Assessment: written
Assessm.period(s): 1A, 1B
(see academic calendar)

Prerequisites:
wb1126, wb1224, wb4304

Follow up:
wb4427

Detailed description of topics:

·         Ozone and global warming implications. Montreal and Kyoto Protocols. Leaktightness requirements. ODP, GWP and TEWI.

·         Overview of the most important refrigeration systems: Mechanical vapour compression refrigerating machines, vapour absorption refrigerating machines, gas cycle refrigerating machines, thermo-electric cooling. Comparison of these systems. Selection criteria.

·         Mechanical vapour compression-refrigerating machines. Carnot cycle. Theoretical and actual refrigeration cycles. The pressure-enthalpy diagram. Entropy production in the components of the refrigeration cycle. Relationship between entropy production and COP. Effect of operating conditions: evaporating temperature, condensing temperature, liquid subcooling, suction vapour superheat and liquid-vapour recuperative heat exchanger. Two-stage operation. Cascade systems. Highlights of components: evaporator, compressor, condenser and expansion devices. Selection criteria.

·         Working fluids. Refrigerants for mechanical vapour compression refrigerating machines: limits of application. Effect of pressure, latent heat of evaporation, safety, price, water, oil, air and high temperature. Media for vapour absorption refrigerating machines: refrigerants and absorbents. Media for gas cycle refrigerating machines. Medium for thermo-electric cooling. Secondary coolants.

·         Control. Basic elements of control. Control loops in refrigeration systems. Working principle of correcting unit: on-off, multi-step and continuous control action. Economic evaluation. Model design of refrigerating systems. Control loops for components: compressor, condensor, expansion device, evaporator. Sensors and controllers.

·         Gas cycle refrigerating machines. Gas-phase cycles: Carnot cycle, Brayton cycle, Stirling cycle and Ackeret-Keller cycle. Cycles ending in the liquid-phase: Linde cycle and Claude cycle. Highlights of the components.

·         Thermo-electric cooling. Vortex-tube. Vortex-wheel.

·         Vapour absorption refrigerating machines. COP. Enthalpy-concentration diagram. Theoretical cycle. Actual cycle. Effect of liquid-liquid heat exchanger in the solution circuit, absorption, rectification, evaporation, external heat exchanging, pressure drop and non-condensables. Intermittent operation. Multistage operation and resorption. Highlights of components.

Course material:

• Dincer, I., "Refrigeration systems and applications", Wiley, Chichester, 2003.

References from literature:

• Cerepnalkovski, I. "Modern refrigerating machines", Elsevier Science Publishers, Amsterdam, 1991.

Remarks (specific information about assesment, entry requirements, etc.):

Goals:
The student must be able to:

1. describe the position and role of “Refrigeration” in society and economy and its environmental impact

2. recognize the different methods to generate refrigeration effect and the most important properties of these methods

3. reproduce and apply thermodynamic concepts in relation to mechanical vapor compression machines taking operating conditions and irreversibilities into account and including first and second law analysis, two-stage, cascade and indirect operation

4. reproduce and apply thermodynamic concepts in relation to vapor absorption machines taking operating conditions and irreversibilities into account and including first law analysis, multi-stage, resorption and intermittent operation

5. reproduce and apply thermodynamic concepts in relation to machines based in gas cycles including the Carnot, Joule-Brayton, Stirling and Ackeret-Keller cycles and cycles that end in the liquid phase as the Linde and Claude cycles

6. reproduce thermodynamic concepts in relation to thermo-electric, compression-resorption, adsorption, magnetic, thermo acoustic and metal hydride machines

7. reproduce the selection criteria for the main components of mechanical vapor compression machines and their main characteristics

8. reproduce and apply selection criteria for working fluids for the different refrigeration systems including volumetric heat capacity, safety and environmental impact

9. describe the working principles of the various part-load control methods for refrigerating machines including on-off, speed, cylinder unloading, suction line and hot-gas bypass control

10. model the processes taking place in vapor compression machines with the purpose of investigating the performance of alternative part-load control methods

Computer use:
Model of the processes taking place in vapor compression machines with the purpose of investigating the performance of alternative part-load control methods.

Laboratory project(s):

Design content:
About 50% of this course deals with discussion of the design methods for the different systems.

Percentage of design: 50%.