Test: Refrigerant Compressors - 1 - Mechanical Engineering MCQ

Air     enters a compressor at a temperature of 27°C. The compressor pressure ratio is 4. Assuming an efficiency of 80%, the compressor work required in kJ/kg is:

Select statements from List-II matching the processes in List-I. Enter your answer as A, B if the correct choice for (1) is (A) and that for (2) is (B)

A centrifugal compressor is suitable for which of the following? 

Which type of valves is generally used in reciprocating refrigerant compressors?

In a single stage reciprocating air compressor, the work done on air to compress it from suction pressure to delivery pressure will be minimum when the compression is 

The capacity of an air compressor is specified as 3 m³/min. It means that the compressor is capable of:

When a burnt out hermetic compressor is replaced by a new one, it is desirable to include in the system a large drier-cum ·strainer also. This is to be placed in

Match List-I (Name of equipment) with List-II (Pressure ratio) and select the correct answer using the code given below the lists:

Which one of the following statements is correct?

In reciprocating compressors, one should aim at compressing the air 

Roots blower is an example of:

Assertion (A): A reciprocating air compressor at sea level would deliver a greater mass of air than a compressor on a mountain.

Reason (R): The compressor ratings are given for “free air”. 

Assertion (A): In multi-stage compressors, the polytropic efficiency is always greater than the isentropic efficiency.

Reason(R): Higher the pressure ration, the greater is the polytropic efficiency.

During steady flow compression process of a gas with mass flow rate of 2 kg/s. increase in specific enthalpy is 15kJ/kg and decrease in kinetic energy is 2 kJ/kg. The rate of heat rejection to the environment is 3kW. The power needed to drive the compressor is:

When are shock waves formed in air compressors?

For a two-stage reciprocating air compressor, the suction pressure is 1.5 bar and the delivery pressure is 54 bar. What is the value of the ideal intercooler pressure? 

What is the preferred intercooler pressure for a two stage air compressor working between the suction pressure p_s and the delivery pressure p_d?

Reciprocating compressors are provided with