Chemical Engineering Thermodynamics - Study Mode
[#166] The following heat engine produces power of 100000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is
Correct Answer
(D) 320, 000 kW
[#167] Degress of freedom at triple point will be
Correct Answer
(A) 0
Explanation
Solution: For a triple point number of components $$= 1$$ Number of phases in equilibrium $$= 3$$ So, by Gibbs phase rule $$f = c - emptyset + 2 = 1 - 3 + 2 = 0$$
[#168] Refrigeration cycle
Correct Answer
(B) Involves transfer of heat from low temperature to high temperature
Explanation
Solution: Refrigeration is just the reverse of heat engine so, it takes heat from low temperature by taking the help of surroundings and transfers it to high temperature reservoir.
[#169] Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as
Correct Answer
(A) P + F - C = 2
Explanation
Solution: The Gibbs phase rule for non-reacting system and for equilibrium system is given as $$F=C-P+2$$
[#170] High pressure steam is expanded adiabati-cally and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process:
Correct Answer
(B) ΔH ≠ 0 and ΔS = 0
Explanation
Solution: For a reversible adiabatic process the entropy change is zero since $$dS = frac{{delta Q}}{T}$$ But the enthalpy change need not be zero since the internal energy and pressure energy may vary during the process.