Refrigeration And Air-Conditioning

Below is this year’s WAEC syllabus for Refrigeration And Air-Conditioning . Note that this syllabus is for both Internal and external candidates.

SCHEME OF EXAMINATION

The examinations shall consist of three papers, all of which must be taken. Papers 1 and 2 shall be composite and will be taken at one sitting.

Paper 1:            This will consist of forty compulsory multiple choice questions.  Candidates will be allowed 1 hour for the paper.  It will carry 40 marks.

Paper 2:            There shall be five essay questions out of which candidates will be expected to answer any four in 1 hour 30 minutes for 60 marks.

Paper 3:        There shall be two practical questions for candidate to answer one of them within 2 hours for 100 marks.

A list of materials (cutting list) shall be made available to the schools not less than two weeks before the paper is taken for their procurement and preparation for the examination.  Candidate shall carry out the task in the presence of an examiner.

Alternatively, the Council may consider using the alternative to practical work testing method in the event of constraints on requisite facilities. In this case, two compulsory questions shall be made available for candidates to answer within 2 hours for 100 marks.  The paper shall test candidates’ real life experience in the workshop, abilities to identify and use requisite tools, use of measuring instruments and trouble shooting, etc.  Free hand sketches of hand tools, circuits and wiring diagrams of refrigeration and air-conditioning systems may also be required.

DETAILED SYLLABUS

S/NO. TOPIC CONTENT PRACTICAL
1 Safety and first aid in the workshop. 1.1.              Workshop rules and regulations

1.2.             Safety devices/equipment – helmet, goggles, safety boots, hand gloves, overall, apron sand bag, fire extinguishers, etc.

1.3.             Accident: causes and prevention techniques.

1.4.             First Aid – materials for First Aid, charts, posters and first aid box, etc.

1.5.             Application of first aid materials.

 

1.2.1           Identification and operation of various types of fire extinguishers

2 Energy, matter and power.

(a)    Energy

 

 

 

 

 

 

 

(b)    Nature of matter.

 

 

 

 

(c)   power.

2.1.     Definition of energy

2.2.     The process of energy              conversion electrical to            mechanical, gas to vapour,            mechanical to heat.

2.3.      Meaning of internal energy.

2.4.      Enthalpy of a fluid substance,             its pressure, volume and            temperature of internal energy.

2.5.     The ph diagram of refrigerant.

2.6.      State of matter – solid, liquid,             gas or vapour.

 

2.7.     Change of state of matter.

2.8.     The meaning of power.

2.9.     Calculation of power used by a            compressor.

2.10.    Unit of power: watts and             kilowatts unit of heat: joules             and kilojoules.

 

2.2.1.   Demonstration of             conversion of             mechanical to heat             energy e.g. rubbing of             palms.

 

 

 

 

2.6.1.    Demonstrate the              conversion of ice              block to water.

3 Temperature and pressure.

(a)    Temperature and          its measurement

 

 

3.1.    Concept of temperature.

3.2.    Different types of thermometer           e.g. gas, resistance, liquid and           thermocouple.

 

 

 

 

 

 

 

 

 

 

 

 

(b)   Pressure and its        measurement

3.3.     Temperature scale conversion

–   centigrade to Fahrenheit

–   Celsius to Kelvin

–   Fahrenheit to rankine

3.4.      International practical             temperature

–   The boiling point of oxygen                  182.97ºC

–   The triple point of water

0.01 ºC

–    The boiling point of water                    100 ºC

3.5.      Concept of pressure

3.6.       Different types of pressure               measuring devices e.g.              barometer, manometer,              bourdon tube gauge.

3.7.       Pressure measurement

3.8.       Uses of suction and high              pressure gauges.

 

3.9.     Effects of temperature, pressure            and volume in refrigeration and            air conditioning systems.

3.10.   Gas law, Boyles law, Charles            law and Dalton’s law.

3.11.   Calculations involving general            gas law.  Formulae:-

–   P1 V1 = P2V2

–   P1 P2

T1     T2

–          V1  = V2

–          T1     T2

–          P1 V1 = P2V2

T1        T2

3.12   Plotting various temperature           scales

 

 

 

 

 

 

 

 

 

 

 

 

 

3.6.1.   Demonstration of the             use of a barometer.

 

 

 

3.8.1.    Demonstrate how              suction and high              pressure gauges are              used to determine the              performance of a              refrigerant.

4 Refrigeration and air conditioning systems.

(a)   Introduction to        refrigeration.

 

 

 

 

 

 

 

 

 

 

 

(b)   Refrigerants

 

 

 

 

 

 

 

 

 

(c)    Air-Conditioning        processes

 

 

4.1.   Refrigeration cycle – Evaporation,          compression, condensation and          expansion.

4.2.   Layout diagram of refrigeration          systems.

4.3.    Types and applications of the           various forms of refrigeration.

4.4.    Principles of operation of forms           of refrigeration system.

4.5.    Functions of the component and           accessories e.g. relay, solenoid           valves, capacitors and           thermostat.

4.6.    Definition and types of           refrigerants

 

4.7.    Chemical names and formulae.

4.8.     Properties and uses of            refrigerants.

4.9.     Refrigerants flow controls e.g.            TEV, AEV, capillary tube.

4.10.    Operations of refrigerant flow             controls.

 

4.11.    Psychometric properties of air.

 

 

4.12.    The processes of air             conditioning: heating and            cooling.

4.13.   Latent and sensible heat,            saturated and super-saturated            vapour.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.6.1.   Identification of             refrigerant by cylinder             colours.

 

 

 

 

 

 

 

4.11.1.   Demonstration of air               conditioning principle                by sling                psychometer.

 

 

 

4.13.1    Demonstration of the               difference between               latent and sensible               heat by use of               methylated spirit on               human skin.

5. Compressors, Condenses and Evaporators

(a)    Compressors

 

 

 

(b)    Condensers.

 

 

 

5.1.   Types of compressors

5.2    Construction of compressors.

5.3.   Working principles of          compressors.

5.4.   Construction of condensers.

 

5.5.   Calculation of heat load on          condensers.

5.6.   Types and functions of liquid          receiver and service valves.

5.7.   Principle of operation of liquid          receiver and service valves.

5.8.   Types of evaporators.

5.9.   Construction and services of          evaporators.

5.10.  Working principles of               evaporators.

5.11.   Heat load estimates on            evaporators.

 

 

 

 

 

 

 

5.4.1.    Demonstrate how to              service a                         condenser.

 

 

 

 

 

 

 

5.9.1.    Demonstrate how to              service evaporators

6. Workshop practices.

(a)    Basic tools used in         refrigeration and         air-conditioning         workshops

 

 

(b)    Fault diagnosis and         trouble shooting.

 

6.1.     Basic tools – hacksaw, coil            spring benders, reamers, tube            cutters, etc.

6.2.     Tools and procedures for            servicing window unit air-           conditioner.

6.3.     Different methods of diagnosing            faults systematic and            observation.

6.4.     Common faults in refrigeration            systems and their symptoms –              leakage, faulty units, faulty            compressor, poor cooling            and current leakage.

 

 

 

 

 

6.2.1.   Servicing of a window              air-conditioner.

 

 

 

 

 

 

(c)    Maintenance and         Testing

6.5.     Techniques of effective repairs             in refrigeration and air-                        conditioning systems.

6.6.      Techniques of trouble shooting              in a given system.

6.7.       Testing for leakages, polarity,              insulation continuity, pressure              and efficiency.

 

6.8.        Maintenance of compressors,               evaporators, motors,                             condensers, valves,                        accumulators and contactors.

 

 

 

 

 

6.7.1.   Demonstrate how to             test for leakages,              polarity continuity and              efficiency.

6.8.1.    Demonstrate how to              repair faults in              compressors,               evaporators, motor               and condensers.

7 Installation processes

(a)    Piping, Ducting and         Trunking

 

 

 

 

 

 

 

 

 

 

(b)   Motors and        generators

 

 

 

 

 

 

(c)   Cold room

 

7.1.     Concept of piping, ducting and            trunking.

7.2.     Piping a condenser and an            evaporator.

7.3.     Ducting, trunking and installation            of air-conditioners.

 

7.4.    Piping, ducting and trunking tools           – mallet hammer, flaring tools,           silver tape, dot-punch, bending           spring, amaflex, hacksaw, PVC            pipes.

7.5.     Types, functions, operations and            application of motors and            generators.

7.6.     Installation procedures for            motors and generators.

7.7.     Maintenance of motors and            generators in a refrigeration            system.

7.8.     Working principles of cold room.

7.9.     Cold room installation            procedures.

 

 

 

 

 

7.3.1.    Installation of  a                split air-conditioner.

 

 

 

 

 

 

 

 

 

 

7.7.1    Servicing of motors              and generators.

7.10.    Factors affecting cold room            operations.
8. Insulation processes

Insulation of refrigeration and air-conditioning system.

8.1.     Importance of insulation of                            refrigeration and air-conditioning            systems.

8.2.     Types of insulating materials –                              glasswool, fibre glass,             polysterene foam, wood,             bitumen, ceramic, etc.

8.3.      Functions and properties of             insulation materials.

8.4.      Procedure for insulating             refrigeration and air-           conditioning systems.

9. Entrepreneurship.

(a)    Business concept.

 

 

 

 

 

 

(b)    Marketing

 

 

 

 

(c)    Accounting

 

9.1.     Concept of business enterprise            and types of businesses – sole             proprietorship, partnership,             limited liability, etc.

9.2.     Sources of finance – loan,            mortgage, shares, overdrafts,            savings, etc.

9.3.     Types, functions of marketing             styles.

9.4.      Meaningful marketing at the             least cost.

9.5.      Marketing protocol and cost.

9.6.      Principles of Accounting.

9.7.      The concept of business as a              separate entity.

9.8.       Ledger, trial balance and             balance sheet.

 

 

 

 

 

 

 

 

 

 

9.4.1.    Carry out a              commercial marketing              survey to set up              refrigeration and

air-conditioning              business.

 

9.8.1.    Preparation of ledger              and balance sheet.


LIST OF FACILITIES AND MAJOR EQUIPMENT/MATERIALS REQUIRED:

  1. Complete tool box (RAC) –             3
  2. Set of oxy-acetylene brazing equipment      –             2
  3. Power pillar drilling machine –             1
  4. Power grinding machine –             1
  5. Portable hand drilling machine –             2
  6. Portable table grinding machine –             2
  7. Vacuum pump –             1
  8. Recovery and recycling machine –             1
  9. Spotter recovery pump –            2
  10. Table vice –             4
  11. Workbench –             2
  12. Hand blower –             1
  13. D. O. T. recovery cylinders big size   –             1
  14. D. O. T. recovery cylinders (medium)         –   1
  15. Manifold gauge                                                             –             2
  16. Reamers –             4
  17. Pipe benders (various sizes) spring and mechanical –             1
  18. Ratchet wrenches –             2
  19. Hacksaw –             4
  20. Pliers (different types)                                                 –             1 each
  21. Set of screwdrivers –             4
  22. Mallet hammers –             2
  23. Ball-pein hammer –             2
  24. Electronic leak detectors –             1
  25. Electronic charging scale –             2
  26. Trolleys –             1
  27. Halogen touch light –             1
  28. Alcometer –             1
  29. Various types of refrigerant (R134A, 600A and 717)

SUGGESTED READING LIST

  1. Ananthranrayazan P. N. (2005) Basic refrigeration and air conditioning 3rd Edition, Tata McGraw Hill, New Delhi.
  1. Whitman, W. C. Johnson, W. M. (1995) Refrigeration’s Air-conditioning Technology 3rd Edition, Delmar Publisher, Albany, N. Y.
  1. Rajput R. K. (2006) Refrigerant and air-conditioning 1st Edition, S. K. Kataria and Sons, Naizarak, Delhi.
  1. Roy J. Dossat. Principles of Refrigeration 4th Edition, Spectrum Publishers.

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