As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio

Which of the following statement(s) is/are incorrect? (i) A turbine is called an impulse turbine if at the inlet of the turbine total energy is only kinetic energy (ii) A turbine is called a reaction turbine if at the inlet of the turbine the total energy is kinetic energy and pressure energy (iii) The inward flow reaction turbine having radial discharge at the outlet is known as Kaplan turbine

A

Only (i)

B

Only (iii)

C

(i) and (ii)

D

(ii) and (iii)

In a newly developed innovative idea brought up by CSIR in India, gas turbine exhaust gas are being utilized to convert feedwater into steam. Certain data of the experiment are as follows: mass flow rate of exhaust gas = 40 kg/hr, enthalpy of exhaust gas at the time of their exit from gas turbine is 600 kJ/kg, steam turbine output as measured by brake dynamometer = 60 hp-sec, thermal efficiency of steam power plant is 0.25, efficiency of exhaust gas in converting feedwater into steam is taken as 50%. Find the enthalpy of exhaust gas remaining after they generate steam from feedwater?

A

350.0KJ/Kg

B

241.2KJ/Kg

C

112.45KJ/Kg

D

512.56KJ/Kg

There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would

A

Remain same

B

Decrease

C

Increase

D

None of the above

Engines are rated at specified conditions. Then which of the following statements are correct? 1. Power developed increases as local temperature increases. 2. Power developed increases as local temperature decreases 3. Power developed is not dependent on local temperature. 4. Power developed increases as local atmospheric pressure increases. 5. Power developed increases as local atmospheric pressure decreases.

A

1 and 4

B

3 and 4

C

3 and 5

D

2 and 4

The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio

A

Increases

B

Decreases

C

First increases and then decreases

D

First decreases and then increases

Which combination of the following statements is correct? The incorporation of reheater in a steam power plant: P: always increases the thermal efficiency of the plant. Q: always increases the dryness fraction of steam at condenser inlet. R: always increases the mean temperature of heat addition. S: always increases the specific work output.

A

P and S

B

Q and S

C

P, R and S

D

P, Q, R and S

Consider the following statements: 1. The air standard efficiency of an Otto cycle is a function of the properties of the working substance (gas) 2. For the same compression ratio and same input, the thermal efficiency of an Otto cycle is more than that of a Diesel cycle 3. Thermal efficiency of a Diesel cycle increases with decrease of cut-off ratio Which of the above statements are correct?

A

1 and 2 only

B

1 and 3 only

C

2 and 3 only

D

1, 2 and 3

The following questions have three statements. Study the question and the statements and decide which of the statement(s) is/are necessary to answer the question. In how many hours tap B can fill the completely empty tank? Statement I: The inlet tap A and the outlet tap C working simultaneously takes 40 hours to fill the tank. Statement II: Efficiency of inlet tap B is equal to efficiency of outlet tap C or 62.5% of the efficiency of inlet tap A. Statement III: The outlet tap C can empty a half filled tank in 12 hours.

A

Statement II and III are sufficient to answer the question.

B

Statement I and II are sufficient to answer the question.

C

Either statement I or III and statement II are sufficient to answer the question.

D

Either statement II or III and statement I are sufficient to answer the question.

E

All the statements are required to answer the question.

The highest pressure gas of a mixture has partial pressure p, the partial pressure of other gases decreases by factor of 2n-1, the partial pressure of second gases decreases by a factor of 2, partial pressure of third gas increases by 4, and so on, if the total pressure of gas mixture is 31p/16, how many gases are present in the mixture?

A

3

B

5

C

10

What is the optimum pressure ratio range for a gas turbine to obtain optimum efficiency?

A

7-8.5

B

10.5-12

C

9.5-10

D

10-20

As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio

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