On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?

Related Mcqs:

1. The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents_____________________?

   A. condensation of the refrigerant vapour
   B. evaporation of the refrigerant liquid
   C. compression of the refrigerant vapour
   D. metering of the refrigerant liquid
   E. none of the above

2. Short horizontal lines on pressure-enthalpy chart show__________________?

   A. constant pressure lines
   B. constant temperature lines
   C. constant total heat lines
   D. constant entropy lines
   E. constant volume lines

3. Vertical lines on pressure-enthalpy chart show constant_______________?

   A. pressure lines
   B. temperature lines
   C. total heat lines
   D. entropy lines
   E. volume lines

4. Allowable pressure on high-pressure side or ammonia absorption system is of the order of_________________?

   A. atmospheric pressure
   B. slightly above atmospheric pressure
   C. 2-4 bars
   D. 5-6 bars
   E. 7-10 bars

5. A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is________________?

   A. Ammonia
   B. Carbon dioxide
   C. Freon
   D. Brine
   E. Hydrocarbon refrigerant

6. The COP of a vapor compression plant in comparison to vapor absorption plant is ________________?

   A. more
   B. less
   C. same
   D. more/less depending on size of plant
   E. unpredictable

7. Formation of frost on evaporator in refrigerator ________________?

   A. results in loss of heat due to poor heat transfer
   B. increases heat transfer rate
   C. is immaterial
   D. can be avoided by proper design
   E. decreases compressor power

8. Critical pressure of a liquid is the pressure_________________?

   A. above which liquid will remain liquid
   B. above which liquid becomes gas
   C. above which liquid becomes vapour
   D. above which liquid becomes solid
   E. at which all the three phases exist together

9. The vapor pressure of refrigerant should be_________________?

   A. lower than atmospheric pressure
   B. higher than atmospheric pressure
   C. equal to atmospheric pressure
   D. could be anything
   E. none of the above

10. Reducing suction pressure in refrigeration cycle_________________?

    A. lowers evaporation temperature
    B. increases power required per ton of refrigeration
    C. lowers compressor capacity because vapour is lighter
    D. reduces weight displaced by piston
    E. all of the above