ME6301 ET 2marks-16marks, ENGINEERING THERMODYNAMICS Question Bank, ET Short Answers – MECH 3rd SEM Anna University

Two mark questions and answers UNIT II

UNIT II SECOND LAW

1. Define Clausius statement.
It is impossible for a self-acting machine working in a cyclic process, to transfer heat from a body at lower temperature to a body at a higher temperature without the aid of an external agency.
2. What is Perpetual motion machine of the second kind?
A heat engine, which converts whole of the heat energy into mechanical work, is known as Perpetual motion machine of the second kind.
3. Define Kelvin Planck Statement. Nov / Dec 2009
It is impossible for a heat engine to produce network in a complete cycle if it exchanges heat only with bodies at a single fixed temperature.
4. Define Heat pump.
A heat pump is a device, which is working in a cycle and transfers heat from lower temperature to higher temperature.
5. Define Heat engine. Nov / Dec. 2011
Heat engine is a machine, which is used to convert the heat energy into mechanical work in a cyclic process.
6. What are the assumptions made on heat engine?
1. The source and sink are maintained at constant temperature.
2. The source and sink has infinite heat capacity.
7. State Carnot theorem. April / May 2011
It states that no heat engine operating in a cycle between two constant temperature heat reservoirs can be more efficient than a reversible engine operating between the same reservoirs. 8. What is meant by
8. What is meant by reversible process?
A reversible process is one, which is performed in such a way that at the conclusion of process, both system and surroundings may be restored to their initial state, without producing any changes in rest of the universe.
9. What is meant by irreversible process?
The mixing of two substances and combustion also leads to irreversibility. All spontaneous process is irreversible.
10. Explain entropy? Nov / Dec 2011
It is an important thermodynamic property of the substance. It is the measure of molecular disorder. It is denoted by S. The measurement of change in entropy for reversible process is obtained by the quantity of heat received or rejected to absolute temperature.

11. What is absolute entropy?
The entropy measured for all perfect crystalline solids at absolute zero temperature is known as absolute entropy.
12. Define availability. May / June 2009
The maximum useful work obtained during a process in which the final condition of the system is the same as that of the surrounding is called availability of the system.
13. Define available energy and unavailable energy. May / June 2012 Available energy is the maximum thermal useful work under ideal condition. The remaining part, which cannot be converted into work, is known as unavailable energy.