Previous year question paper for ARAC (Diploma Automobile Engineering 5th)

1. Principles of Refrigeration (10 hrs)

1.1 Meaning

1.2 Refrigeration Methods

1.3 Units of Refrigeration

1.4 Reversed Carnot Cycle

1.5 Heat Pump

1.6 Coefficient of Performance

1.7 Rating of Refrigeration Machines

2. Refrigeration Systems (12 hrs)

2.1 Air Refrigeration cycle-applications and its limitations.

2.2 Vapour Compression Cycle.

2.3 Effect of sub cooling and super heating.

2.4 Departure of actual vapour compression cycle from theoretical cycle.

2.5 Effect of varying condensing and suction temperature on coefficient of

performance.

2.6 Simple mathematical calculation with pressure - enthalpy charts.

2.7 Vapour absorption cycle.

2.8 Actual vapour absorption cycle and application

3. Refrigerants (06 hrs)

3.1 Important properties of a refrigerant.

3.2 Properties and application of commonly used refrigerants such

 as R11, R12, R22, NH3 and Water.

3.3 Newer refrigerants.

4. Refrigeration System, Components and Controls (04 hrs)

4.1 Function, types, specification and constructional details of components

such as compressor, condenser, throttling device, evaporator,

oil, separator, accumulator.

4.2 Various controls - solenoid valve, thermostat, low pressure/high

pressure cut out, safety switch.

5. Psychrometry (08 hrs)

5.1 Various terms- Dry and wet bulb temperatures, saturation, dew point,

adiabatic saturation, temperature, relative humidity, absolute humidity,

humidity ratio.

5.2 Psychrometric chart and its uses.

5.3 Psychrometric processes - sensible heating and sensible cooling,

humidification and dehumidification, cooling and dehumidification, heating

and humidification, and their representation of psychrometric chart.

5.4 Simple problems.

6. Air Conditioning (06 hrs)

6.1 Introduction

6.2 Metabolism in human body

6.3 Human comfort

6.4 Applications of air-conditioning

7. Air conditioning System (10 hrs)

7.1 Principles of automobile air conditioning.

7.2 Air distribution systems, concept of filter, damper, fan, blower, air register

and diffuser, case/duct system, engine cooling and heater circuit.

7.3 Auto air conditioning systems - operating conditions, car air conditioning,

bus air conditioning, truck air conditioning, performance, rating, typical

installations.

7.4 Causes of failure of auto air conditioners.

7.5 Trouble shooting