Chapter 6, Problem 6.35CU

The entropy of an ideal gas depends on both T and P. The function s° represents only the temperature-dependent part of entropy.

D2

Starting from the 1st law of thermodynamics, prove that the change in the T₂ entropy of an ideal gas undergoing a process is equal to C, In + R In / T₁

A unit mass of a substance undergoes an irreversible process from state 1 to state 2 while gaining heat from the surroundings at temperature T in the amount of q. If the entropy of the substance is s1 at state 1 and s2 at state 2, the entropy change of the substance Δs during this process is (a) Δs < s2 – s1 (b) Δs > s2 – s1 (c) Δs = s2 – s1 (d) Δs = s2 – s1 + q/T (e) Δs > s2 – s1 + q/T

Based on this question, can you explain in words the theory behind the second law of thermodynamics with this question and how it is solved? Thank you

When two systems are in contact, the entropy transfer from the warmer system is equal to the entropy transfer into the cooler one at the point of contact. That is, no entropy can be created or destroyed at the boundary since the boundary has no thickness and occupies no volume.

Steam enters a turbine operating at a steady state at a pressure of 4 MPa, at temperature of 400 degrees Celcius, and a velocity of 200m/s . Saturated vapor exits at 100 degrees Celcius with a velocity of 100 m/s. Heat transfer from the turbine to its surroundings takes place at the rate of 20 kJ/kg of steam at a location where the average surface temperature is 350K. (a) Write the energy and entropy balance equations for a control volume the includes only the turbine and its contents (b) Determine the work produced, in kJ/kg of steam flowing. (c) For a control volume that includes only the turbine and its contents, calculate the rate of entropy production in kJ/kg*K (d) Assume the turbine described above is located in a factory where  the ambient temperature is 27 degrees Celcius. Determine the rate of entropy production in kj/kg*Kof steam, for an inlarged control volume that included the turbine and enough of its immediate surroundings so that heat transfer takes place from the…

An ideal gas initially at 70 °C and 1 bar undergoes the following reversible processes, completing a cycle. 1-2: the gas is compressed adiabatically to 150 °C. 2-3: it is then cooled at constant pressure from 150 °C to 70 °C. 3-1: finally, the gas is expanded isothermally to a final pressure at 1 bar. Take Cp 1.005 kJ/g K, Cv= 0.705 kJ/g K. Sketch the cycle P-V diagram for the entire cycle. Calculate W,Q and Au for the entire cycle.

1. 1 kg of propane contained within a piston-cylinder assembly undergoes a process from an initial state of Pi = 15 bar and X = 50% to a final state of P2 =4 bar, T2 = 24°C. The work done by the propane during the process is 50 kJ, and heat transfer to the surroundings occurs at a surface with an average temperature of 47°C. Kinetic and potential energy changes can be neglected. Determine the entropy production of the system (kJ/K).