Refrigeration and Air Conditioning

11. Ammonia-absorption refrigeration cycle requires

1. very little work input
2. maximum work input
3. nearly same work input as for vapour compression cycle
4. zero work input
5. none of the above.

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12. An important characteristic of absorption system of refrigeration is

1. noisy operation
2. quiet operation
3. cooling below 0°C
4. very little power consumption
5. its input only in the form of heating.

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13. Aqua ammonia is used as refrigerant in the following type of refrigeration system

1. compression
2. direct
3. indirect
4. absorption
5. none of the above.

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14. At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant

1. decreases
2. increases
3. remains same
4. depends on other factors
5. none of the above.

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15. Choose the correct statement

1. A refrigerant should have low latent heat
2. If operating temperature of system is low, then refrigerant with low boiling point should be used
3. Precooling and subcooling bf refrigerant are same
4. Superheat and sensible heat of a. refrigerant are same
5. Refrigerant is inside the lubes in case of a direct-expansion chiller.

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16. Choose the wrong statement

1. Temperature of medium being cooled must be below that of the evaporator
2. Refrigerant leaves the condenser as liquid
3. All solar thermally operated absorption systems are capable only of intermittent operation
4. frost on evaporator reduces heat transfer
5. refrigerant is circulated in a refrigeration system to transfer heat.

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17. Clapeyron equation is a relation between

1. temperature, pressure and enthalpy
2. specific volume and enthalpy
3. temperature and enthalpy
4. temperature, pressure, and specil volume
5. temperature, pressure, specific volur and'enthalpy.

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18. Condensing temperature in a refrigerator is the temperature

1. of cooling medium
2. of freezing zone
3. of evaporator
4. at which refrigerant gas becomes liquid
5. condensing temperature of ice.

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19. Cooling water is required for following equipment in ammonia absorption plant

1. condenser
2. evaporator
3. absorber
4. condenser and absorber
5. condenser, absorber and separator (rectifier).

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20. Critical pressure of a liquid is the pressure

1. above which liquid will remain liquid
2. above which liquid becomes gas
3. above which liquid becomes vapour
4. above which liquid becomes solid
5. at which all the three phases exist together.

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