For the same compression ratio, the efficiency of Brayton cycle is ____ the efficiency of Otto cycle.

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

Otto cycle efficiency is higher than Diesel cycle efficiency for the same compression ratio and heat input because in Otto cycle

A

Heat rejection is lower

B

Expansion and compression are isentropic

C

Combustion is at constant volume

D

Maximum temperature is higher

Otto cycle efficiency is higher than Diesel cycle efficiency for the same compression ratio and heat input because in Otto cycle ____________

A

combustion is at constant volume

B

expansion and compression are isentropic

C

maximum temperature is higher

D

heat rejection is lower

For the same compression ratio and work capacity, Brayton cycle handles ____ range of volume and ____ range of pressure and temperature than does Otto cycle.

A

larger, smaller

B

smaller, larger

C

both are same

D

none of the mentioned

For the same heat input & compression ratio, efficiency of Otto cycle is higher than that of diesel cycle, because in Otto cycle.

A

Heat rejection is lower

B

Expansion & compression are isentropic

C

Maximum temperature is higher

D

Combustion is at constant volume

For the same heat input & compression ratio, efficiency of Otto cycle is higher than that of diesel cycle, because in Otto cycle.

A

Heat rejection is lower

B

Expansion & compression are isentropic

C

Maximum temperature is higher

D

Combustion is at constant volume

Group I shows different heat addition processes in power cycles. Likewise, Group II shows different heat removal processes. Group III lists power cycles. Match items from Groups I, II and III. Group I Group II Group III P. Pressure constant S. Pressure constant 1. Rankine cycle Q. Volume constant T. Volume constant 2. Otto cycle R. Temperature constant U. Temperature constant 3. Carnot cycle 4. Diesel cycle 5. Brayton cycle

A

P – S – 5, R – U – 3, P – S – 1, Q – T - 2

B

P – S – 1, R – U – 3, P – S – 4, P – T - 2

C

R – T – 3, P – S – 1, P – T – 4, Q – S - 5

D

P – T – 4, R – S – 3, P – S – 1, P – S - 5

Which factor leads to lower thermal efficiency of an actual Otto cycle in comparison of ideal Otto cycle?

A

Increase in specific heat ratio of working fluid with rise in temperature.

B

Decrease in specific heat ratio of working fluid with rise in temperature.

C

Decrease in specific heat of working fluid with rise in temperature.

D

No change in specific hear with change in temperature.

From an alloy, two specimens are machined and tested separately under tension and compression. The engineering stress-strain curves as well as the true stress-true strain curves for tension and compression are plotted in the same diagram. Identify the correct statements:
P. The engineering stress-strain curves in tension and compression are identical.
Q. The true stress-true strain curve in compression is lower than the true stresstrue strain curve in tension due to Bauschinger effect.
R. The true stress-true strain curve in tension is above the corresponding engineering stress-strain, curve.
S. The true stress-true strain curve in tension and compression are identical.

A

P, Q

B

Q, R

C

Q, S

D

R, S

For the same compression ratio, the efficiency of Diesel cycle is __________ Otto cycle.

A

Greater than

B

Less than

C

Equal to

D

None of these

For the same compression ratio, the efficiency of Brayton cycle is ____ the efficiency of Otto cycle.

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