# Mechanical Engineering - Thermodynamics - Discussion

Discussion Forum : Thermodynamics - Section 1 (Q.No. 3)
3.
The efficiency and work ratio of a simple gas turbine cycle are
low
very low
high
very high
Explanation:
No answer description is available. Let's discuss.
Discussion:
34 comments Page 1 of 4.

Soham Mitra said:   8 years ago
Rankine cycle used in thermal power plants deals on heating up water in constant pressure while changing its phase. The process will has greater thermal efficiency compared to any other cycles. Otto cycle can't be used because heat supplied to the system is in constant volume process, not allowing steam to expand properly.

If Otto cycle forced to used, the pressure will be too high for any material (vessel) to withstand. Diesel also can't be used, because while heat supplied to the system, the fluid deliver work to the surrounding. This not applicable because the work should be extracted by steam turbine.

YOGESH GAYAKE said:   8 years ago
But my question is that turbine is used to rotate the generator for generating the electricity & its rotate with the help of steam pressure. Then how we can calculate its efficiency & work ratio. But still we assure that the 70% of power from turbine is used to run the compressor itself. So it's correct but, how we can say its very low. Please suggest answer.

Chauhan Hardik N. said:   8 years ago
I think that, since the specific volume (reciprocal of density) of air is high, the compression of air requires more work.

Hence, the major fraction of the work developed by the turbine is utilized in driving the compressor.

Therefore, the efficiency of the simple gas turbine plant is too low.

Rajkumar said:   10 years ago
Since the specific volume (reciprocal of density) of air is high, the compression of air requires more work. Hence, major fraction of the work developed by the turbine is utilized in driving the compressor. Therefore, the efficiency of the simple gas turbine plant is too low.

Anshu maan mishra said:   1 decade ago
The ratio of the actual work output of the turbine to the work output that would be achieved if the process between the inlet state and the exit state was isentropic.

DK SINGHGUPTA said:   9 years ago
We all know that work ratio-turbine work /net work that means turbine work means positive work so the answer is low but how the answer is very low.

Because there will be more availability in the exit of the turbine. That's why rankine cycle is used combined with gas power plant.

Awinash kumar said:   1 decade ago
Mechanical efficiency of gas turbine is about 95%. It is not clear in question although thermal efficiency is about 15-20%.