Coursecode: wb4410A
Coursename: Refrigeration Fundamentals

DUT creditpoints: 2
ECTS creditpoints: 3

Faculty of Mechanical Engineering and Marine Technology

Lecturer(s): Machielsen, ing. C.H.M., Infante Ferreira, dr. ir. C. A.

Tel.: 015-27 84445

Catalog data:
Refrigeration fundamentals. Historical overview. Ozone and global warming issues, the 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 / 1B
Hours p/w: 2
Other hours:
Assessment: written
Assessm.period(s): 2, 3
(see academic calendar)

Prerequisites:
wb1126, wb1224, wb4304

Follow up:
wb4427

Detailed description of topics:

·         Introduction. Historical notes.

·         Ozone and global warming implications. The Montreal Protocol. Leaktightness requirements. STEK-provisions. ODP, GWP and TEWI.

·         The working field of refrigeration.

·         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 and differences among themselves. 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. Reasons for application. Choice of intermediate pressure. Layout of two-stage systems. 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. Criteria. 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. Physical model. Mathematical model. Model design of correcting unit. SIMULINK model. 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:

• Arora, C. P., "Refrigeration and air conditioning", Tata McGraw-Hill Publishing Company Ltd., New Delhi, 1991.
• Brodowicz, K. en T. Dyakowski, "Heat pumps", Butterworth-Heinemann Ltd, Oxford, 1993.

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

References from literature:

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

Goals:
This course aims at giving an overview of and a deeper understanding of the most important refrigerating systems and their sizing-techniques. The knowledge gained in the thermodynamic courses is used to come to evaluation criteria for actual systems. The different systems are discussed using illustrating examples.

Computer use:
Model design of refrigerating systems with SIMULINK.

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%.