SECOND LAW

According to Kelvin-Planck's statement of second law of thermodynamics,

• it is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

• it is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

• it is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body

• none of the above

Which is the incorrect statement about Carnot cycle?

• It is used as the alternate standard of comparison of all heat engines.

• All the heat engines are based on Carnot cycle.

• It provides concept of maximising work output between the two temperature limits.

• all of the above

The area under the temperature-entropy curve (T - s curve) of any thermodynamic process represents

• heat absorbed.

• heat rejected

• either (a) or (b)

• none of these

Which of the following is the correct statement of the second law of thermodynamics?

• It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work.

• It is impossible to transfer heat from a body at a lower temperature to a higher temperature, without the aid of an external source

• There is a definite amount of mechanical energy, which can be obtained from a given quantity of heat energy.

• all of the above

The efficiency of Carnot cycle depends upon

• temperature limits

• pressure ratio

• volume compression ratio

• cut-off ratio and compression ratio

The gas turbine cycle with regenerator improves

• thermal efficiency

• work ratio

• avoids pollution

• none of these

A reversed heat engine

• receives heat from a low temperature region

• gives heat to a high temperature region

• receives a net inflow of work

• all of the mentioned

For a heat pump, coefficient of performance is given by (Q1 is the heat taken from low temperature region and Q2 is the heat given to high temperature region)

• Q1/(Q1-Q2)

• Q2/(Q1-Q2)

• 1- (Q1/Q2)

• 1- (Q2/Q1)

For the same T1 and T2, COP increases with ____ in temperature difference.

• increase

• decrease

• no change

• none of the mentioned

In absorption system, compressor in vapour compression cycle is replaced by absorber-generator assembly.

• true

• false