Series OSS                                                                                                                              Code No. 113

                                                        AIR-CONDITIONING AND REFRIGERATION – IV
                                                                                      (Theory)
Time allowed : 3 hours                                                                                                        Max. Marks: 40

Note :    Attempt any five questions. All questions carry equal marks.

 

1. Briefly describe the following :           4x2
(a)    Package unit
(b)    Heating and humidifying equipment

 

2. Why are ducts used in an air-conditioning system ? List the factors due to which pressure of air falls in a duct.     8

 

3. Differentiate between sensing elements and actuating elements, used in a refrigeration control system.  Give examples of both types of elements.                    8

4. Describe the functions and working of a modulating motor.                           8

 

5. List various electrical faults, usually found in a domestic refrigerator. Explain their preventive and breakdown remedial measures.                     8

 

6. Explain the procedure of charging through suction line, with the help of a neat diagram.                   8

 

7. Describe the working of the following
(a)    Compressor
(b)    Relays

 

8. Write short notes on any two of the following :
(i)      Bypass control
(ii)     Safety switches
(iii)    Pressure testing
(iv)    Cooling coil