Gas turbine cycle with regenerator……….
increases thermal efficiency.
allows high compression ratio.
decreases heat lost in exhaust.
increases the work output.
By incorporating which of the following methods, the specific work output of open cycle gas turbine power plant can be improved?
Only intercooling.
Only reheating.
Only heat exchanger.
Both intercooling and reheating.
Which one of the following conditions has to apply for a heat exchanger to work in a Brayton cycle?
Turbine exit temperature should be less than compressor exit temperature.
Turbine exit temperature should be more than compressor exit temperature.
Turbine exit temperature should be equal to compressor exit temperature.
It does not depend upon the turbine and compressor exit temperatures.
Common Data for Questions Q4 to Q8
In a Brayton cycle, air enters the compressor at 1 bar, 300 K and is compressed to a pressure ratio of 5. The air is then heated first in a heat exchanger and then in combustion chamber to a maximum permissible temperature of 1100 K. The heated air is then expanded in a two-stage turbine such that expansion work is maximum. After the first stage of turbine, the air is reheated to 1100 K. The compressor has an isentropic efficiency of 88%. The isentropic efficiency of both the turbines is 85 % and the heat exchanger has an effectiveness of 66 %. Determine the following: (considering properties of air as Cp = 1.005 kJ/kg K, specific heat ratio = 1.4)
Actual temperature (K) at the exit of compressor is ..........
387
475
499
436
Actual temperature (K) at the exit of low-pressure turbine is ..........
936
908
874
769
Total heat added (kJ/kg) into the combustion chamber and reheater is ..........
526
332
387
551
The back work ratio of the cycle is ..........
0.52
0.48
0.37
0.29
Thermal efficiency (%) of the cycle is ..........
21
40
27
35
Common Data for Questions Q9 to Q13
A gas turbine engine consists of a two-stage compression with perfect intercooling and a turbine. Air is taken in at a pressure and temperature of 1 bar and 278 K respectively. The compressed air is passed through a heat exchanger and then the combustion chamber. The heat exchanger has an effectiveness of 70%. The turbine inlet pressure and temperature are 7 bar and 1000 K respectively. The isentropic efficiency of both the compressors is 90% and that of turbine is 86%.
(Consider: for air, Cp = 1.005 kJ/kgK, Specific heat ratio = 1.4)
Based on the above data, answer the given sub questions:
Total work (kJ/kg) consumed by the compressors is ..........
241
199
157
100
Heat added (kJ/kg) into the combustion chamber is ..........
253
369
446
304
Back work ratio of the cycle is ..........
0.49
0.42
0.38
0.54
Net work output (kJ/kg) of the cycle is ..........
170
159
198
181
Efficiency (%) of the cycle is ..........
42
26
38
51
Where are the ans
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