The unavailable energy is the product of the lowest temperature of heat rejection and the change of entropy of system during the process of supplying heat.

Related MCQs

• The entropy increase due to internal irreversibility is also called entropy production or entropy generation.
• 1.6 Kg of air is expanded at constant pressure from 100°C to 0°C resulting in entropy change of - 2.0 J/K 3.2 Kg of air is cooled at constant volume from 100°C to 0°C with a change in entropy of -3.0 J/K. The ratio Cp/ Cv is
• In a cyclic heat engine operating between a source temperature of 600°C & a sink temperature of 20°C, the least rate of heat rejection per kW net output of the engine is
• The available energy is known as          and the unavailable energy is known as          
• According to entropy principle, the entropy of an isolated system can never decrease and remains constant only when the process is reversible.
• The rate of entropy increase of the control volume          or          the net rate of entropy transfer to it.
• The rate at which entropy is transferred out must          the rate at which entropy enters the control volume.
• A heat engine is supplied with 250 kJ/s of heat at a constant fixed temperature of 227°C. The heat is rejected at 27°C. The cycle is reversible, if the amount of heat rejected is
• Consider the following statements: The definition of 1. temperature is due to zeroth law of thermodynamics 2. entropy is due to first law of thermodynamics 3. internal energy is due to second law of thermodynamics 4. reversibility is due to Kelvin-Planck's ststement of these statements
• For any reversible process, the change in entropy of the system & surroundings is