Multi stage vapour compression

Multiple Choice

What is the significance of using multi-stage vapour compression refrigeration systems in industrial applications?

• They allow for higher temperature lifts, making them suitable for processes requiring very low evaporator or very high condensing temperatures.

• They are only used for small-scale household refrigeration.

• They reduce the need for temperature control in chemical industries.

• They eliminate the use of condensers in refrigeration systems.

Multiple Choice

Which of the following is a consequence of increasing temperature lift in single stage refrigeration systems?

• The system becomes more efficient

• The system becomes impractical

• The system operates at lower pressures

• The system requires less energy

Multiple Choice

For fluorocarbon and ammonia based refrigeration systems, which system is used for temperatures below -60°C?

• Single stage system

• Two-stage system

• Three-stage system

• Cascade system

Multiple Select

Which of the following are classifications of multi-stage refrigeration systems?

• Multi-compression systems

• Multi-evaporator systems

• Cascade systems

• Single stage systems

Multiple Select

Which of the following statements about the saturated liquid and vapour in the flash tank is/are correct?

• The saturated liquid at point 8 is fed to the evaporator after throttling.

• The saturated vapour at point 3 is compressed to condenser pressure.

• The saturated vapour at point 3 is throttled to evaporator pressure.

• The saturated liquid at point 3 is compressed to condenser pressure.

Multiple Choice

What is the main function of a flash tank in a refrigeration system?

• To separate refrigerant liquid and vapour at intermediate pressure

• To compress refrigerant to high pressure

• To cool the refrigerant

• To heat the refrigerant

Water cooled = Closed Intercooling, Flash Tank = open intercooling

Multiple Select

Which methods can be used to achieve intercooling of vapour in multi-stage compression systems?

• Water-cooled heat exchanger

• Refrigerant in the flash tank

• Direct expansion

• Air-cooled condenser

Multiple Choice

What is one benefit of intercooling in a compressor system?

• It increases compressor discharge temperature

• It reduces work input and improves lubrication

• It saturates the refrigerant at the inlet

• It increases mass flow rate

Multiple Choice

Which of the following statements about intercooling using liquid refrigerant is correct?

• It is always effective for all refrigerants

• It is not effective for R12 and R22

• It increases power input for ammonia

• It reduces compressor discharge temperature for R12

Multiple Choice

Which of the following is a disadvantage of the multi-stage system with flash gas removal and intercooling?

• Reduced compressor discharge temperature

• Higher refrigerating effect

• Possibility of liquid flashing ahead of the expansion valve

• Lower pressure drop

Multiple Choice

What is the primary function of the liquid subcooler in the refrigeration system shown in the diagram?

• To increase the temperature of the refrigerant before entering the evaporator

• To reduce the temperature of the refrigerant before entering the expansion valve

• To compress the refrigerant vapor

• To remove moisture from the refrigerant

( Open Intercooling )

Multiple Select

Which components are common to both the flash tank system for flash gas removal and the flash tank system for intercooling only?

• Compressor - I and Compressor - II

• Evaporator and Condenser

• Flash chamber and Expansion valve

• All of the above

Multiple Choice

In the two-stage system with flash tank for intercooling only, what is the purpose of the intercooler located between the first and second stage compressors?

• To increase the pressure of the refrigerant

• To reduce the temperature of the refrigerant vapor before entering the second stage compressor

• To separate liquid and vapor phases

• To condense the refrigerant

• Heat Pump Systems

Multiple Choice

In which industry might you require an evaporator temperature as low as -40°C?

• Frozen food industry

• Chemical industry

• Pharmaceutical industry

• Textile industry

Open Ended

Explain why multi-stage vapour compression refrigeration systems are preferred over single stage systems in certain industrial applications.