RAC-VCR Systems (CO2)

The correct sequence of the components of a vapour compression refrigerator is

• Evaporator, compressor, condenser and throttle valve

• Throttle valve, evaporator, condenser and compressor

• Evaporator, compressor, throttle valve and condenser

• Condenser, compressor, throttle valve, evaporator

A single-stage VCR system cannot be used to produce ultra-low temperatures because

• Refrigerants for ultra-low temperatures are not available

• Ice formation takes place at ultra-low temperatures

• Efficiency will decrease considerably

• Heat leakage into the system will be excessive

h at start, end of compression & at end of condensation are 185 kJ/kg, 210 kJ/kg & 85kJ/kg. COP=

• 0.25

• 5.34

• 4

• 1.25

Replacing water cooled condenser with air-cooled in VCR system with constant evaporator pressure causes

• Decrease in condensation pressure

• Decrease in pressure ratio

• Decrease in power consumption

• Increase in condensation temperature

In a simple vapour compression cycle, the refrigerant, immediately after expansion valve is

• Wet vapour

• Saturated liquid

• Subcooled liquid

• Dry vapour

The chemical formula for R134a is

• CHClF4

• C2Cl3F3

• C2Cl2F4

• C2H2F4

Which one of the following is responsible for the operation of a thermostatic expansion valve?

• Pressure changes in evaporator

• Temperature changes in evaporator

• Degree of superheat in evaporator

• Degree of subcooling in evaporator

The VCR cycle represented is in which coordinate system, with state 1 as exit of evaporator

• P-h

• T-s

• T-h

• P-s

Which of the following statements regarding ammonia absorption system is correct? The solubility of ammonia in water is

• A function of the temperature and pressure of the solution

• A function of the pressure of the solution irrespective of the temperature

• A function of the temperature of the solution alone

• Independent of the temperature and pressure of the solution

Cooling tower approach is the difference between...

• Dry bulb and wet bulb temperature

• Water outlet and water inlet temperature

• Water outlet and condenser temperature

• Water outlet and wet bulb temperature