Test: Refrigerant Compressors - 2 - Mechanical Engineering MCQ

The discharge pressure of the compressor in the refrigeration system goes up due to the

Which one of the following statements is true?

Two-stage compressors takes in air at 1.1 bar and discharges at 20 bar. For maximum efficiency, the intermediate pressure is:

A 3-stage reciprocating compressor has suction pressure of 1 bar and delivery pressure of 27 bar. For minimum work of compression, the delivery pressure of 1st stage is:

The heat rejection by a reciprocating air compressor during the reversible compression process AB, shown in the following temperatureentropy diagram, is represented by the area: 

Phenomenon of choking in compressor means

Assertion (A ): T he isothermal efficiency of a reciprocating compressor becomes 100% if perfect cooling of the fluid during compression is attained.

Reason (R): Wor k do ne in a reciprocating compressor is less if the process of compression is isothermal rather than polytropic. 

The suction pressure is 1 bar and delivery pressure is 125 bar. What is the ideal intermediate pressure at the end of first stage for a 3-stage air compressor?

When the discharge pressure is too high in a refrigeration system, high pressure control is installed to:

Which one of the following statements is true?

For a multistage compressor, the polytropic efficiency is:

The usual assumption in elementary compressor cascade theory is that 

In a reciprocating air compressor the compression works per kg of air. 

Consider the following statements:

1. Reciprocating compressors are best suited for high pressure and low volume capacity.  

2. The effect of clearance volume on power consumption is negligible for the same volume of discharge  

3. While the compressor is idling, the delivery valve is kept open by the control circuit.  

4. Inter-cooling of air between the stages of compression helps to minimize losses. 

Of these statements:  

In a two-stage reciprocating air compressor, the suction and delivery pressures are 1 and 4 bar respectively. For maximum efficiency, the intercooler pressure is  

The optimum intermediate pressure P_i for a gas turbine plant operating between pressure limits P₁ and P₂ with perfect inter cooling between the two stages of compression (with identical isentropic efficiency is given by:  

3-stage reciprocating compressors have suction pressure of 1 bar and delivery pressure of 27 bar. For minimum work of compression, the delivery pressure of first stage is:

Four-stage compressor with perfect inter-cooling between stages compresses air from 1 bar to 16 bar. The optimum pressure in the last intercooler will be:

Which of the following statements is not correct for the volumetric efficiency of a reciprocating air compressor? 

Which of the following statements are correct for multi staging in a reciprocating air compressor?

1.It decreases the volumetric efficiency.  

2.The work done can be reduced.  

3. small high-pressure cylinder is required.  

4.The size of flywheel is reduced. 

Select the correct answer using the codes given below 

Consider the following statements

The volumetric efficiency of a reciprocating compressor can be enhanced by:

1. Heating the intake air  

2. Decreasing the clearance volume        

3. Cooling the intake air 

Which of these statements is/are correct? 

The ratio of the clearance volume to the displacement volume of a R12 reciprocating compressor is 0.05. Specific volume at inlet and outlet of compressor are 0.04 and 0.02 m³/kg respectively. Volumetric efficiency of the compressor is:

Consider the following statements:The volumetric efficiency of a compressor depends upon

1. Clearance volume

2. Pressure ratio  

3. Index of expansion 

Of these correct statements are:  

A gas engine has a swept volume of 300 cc and clearance volume of 25 cc. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. What is the volume of the mixture taken in per stroke?

Which of the following techniques are employed for control of reciprocating compressors? 

1. Throttle control  

2. Clearance control

3. Blowing air to waste  

Select the correct answer using the code given below:

What does application of centrifugalair compressors lead to

In centrifugal compressor terminology, vane less space refers to the space between