Engineering Questions with Answers - Multiple Choice Questions

# Thermal Engineering MCQ’s – Brayton Cycle

1 - Question

Gas turbine works on _____
a) Dual cycle
b) Otto cycle
c) Brayton cycle
d) Diesel cycle
Explanation: Brayton cycle is used in gas power plant. It is used in open system that is gas turbine.

2 - Question

The compression ratio (r) of dual cycle is equal to _________
a) r = volume of the cylinder at the beginning of the compression/volume of the cylinder at the end of the compression
b) r = volume of the cylinder at the end of the compression/ volume of the cylinder at the beginning of the compression
c) r = clearance volume/ volume of the cylinder at the beginning of the compression
d) r = volume of the cylinder at the end of the compression/clearance volume
Explanation: compression ratio of dual cycle (r)=sweptvolume+clearancevolumeclearancevolume r=volume of the cylinder at the beginning of the compression/volume of the cylinder at the end of the compression

3 - Question

For same maximum pressure and heat input, most efficient cycle is _________
a) Dual cycle
b) Rankine cycle
c) Brayton cycle
d) Diesel cycle
Explanation: Efficiency of brayton cycle is directly proportional to pressure ratio. Therefore for maximum pressure and heat input brayton cycle is most efficient.

4 - Question

Which of the following methods cannot be used to increase the efficiency of brayton cycle?
a) Decreasing pressure ratio
b) Increasing pressure ratio
c) Regeneration
d) Heat exchanger
Explanation: Heat exchanger and regeneration is used to increase the efficiency of brayton cycle. Also, efficiency of brayton cycle is directly proportional to pressure ratio.

5 - Question

In a brayton cycle heat addition takes place __________
a) At constant volume process
b) At constant pressure process
c) First at constant volume then at constant pressure process
d) First at constant pressure then at constant volume process
Explanation: The sequence of processes in brayton cycle is isentropic compression, isobaric heat addition, isentropic expansion and isobaric heat rejection. Therefore heat addition takes place at constant pressure process

6 - Question

In a brayton cycle heat rejection takes place ____
a) At constant volume process
b) At constant pressure process
c) First at constant volume then at constant pressure process
d) First at constant pressure then at constant volume process
Explanation: The sequence of processes in brayton cycle is isentropic compression, isobaric heat addition, isentropic expansion and isobaric heat rejection. Therefore heat rejection takes place at constant pressure process.

7 - Question

In brayton cycle regenerator is placed between __________
a) Turbine and heat exchanger
b) Turbine and intercooler
c) Compressor and intercooler
d) Compressor and heat exchanger
Explanation: In regenerative brayton cycle a regenerator is placed between compressor and heat exchanger. The exhaust from turbine before entering in heat exchanger and then compressed in compressor.

8 - Question

Reheating will _______ the efficiency of brayton cycle.
a) Decreases
b) Increases
c) Zero
d) Remain same
Explanation: Reheating increases the net work output. Reheating necessarily decreases the efficiency.

9 - Question

If regeneration is also used along with reheating the efficiency will _____
a) Decreases
b) Increases
c) Zero
d) Remain same
Explanation: Regeneration in the brayton cycle increases efficiency by recovery of waste heat. Hence if regeneration is also used along with reheating the efficiency will increase.

10 - Question

What is the effect of regeneration in brayton cycle work output?
a) Work output increases
b) Work output decreases
c) Work output becomes zero
d) Work output doesn’t change
Explanation: Regeneration in the brayton cycle increases efficiency by recovery of waste heat. It doesn’t change the net work output.

11 - Question

In how many stages the compression process is divided in intercooling?
a) One
b) Two
c) Three
d) Five
Explanation: In intercooling the compression process is divided into two stages. Air is compressed in first stage is cooled then further compressed in second stage.

12 - Question

Reheat and regeneration in combination used to increases ________
a) Net work output
b) Efficiency
c) Both net work output and efficiency
d) Doesn’t change net work output and efficiency
Explanation: Reheating increases the net work output. Reheating necessarily decreases the efficiency. Regeneration in the brayton cycle increases efficiency by recovery of waste heat. It doesn’t change the net work output.

13 - Question

Intercooling and regeneration in combination used to increases _________
a) Net work output
b) Efficiency
c) Doesn’t change net work output and efficiency
d) Both net work output and efficiency