Concept explainers
a)
The total entropy change and exergy destruction by treating the mixture as an ideal gas.
a)
Answer to Problem 73P
The entropy generated is
The energy destroyed is
Explanation of Solution
Write the entropy balance equation to obtain the expression of entropy generation in terms of
Here, mass of
Write the expression to obtain the energy destroyed during a process
Here, initial temperature is
Conclusion:
Refer Table A-2b, “Ideal gas specific heats of various common gases”, obtain the specific heat at constant pressure of
From Equation (I) obtain the value of
The partial pressure of
Here, constant pressure specific heat is
Substitute 6 kg for
From Equation (I) obtain the value of
The partial pressure of
Substitute
Substitute
Thus, the entropy generated is
Substitute 293 K for
Thus, the energy destroyed is
b)
The total entropy change and exergy destruction by treating the mixture as a non ideal gas using Amagat’s law.
b)
Answer to Problem 73P
The entropy generation is
The energy destroyed is
Explanation of Solution
Write the expression to obtain the initial reduced temperature of
Here, critical temperature of
Write the expression to obtain the initial and final reduced pressure of
Here, critical temperature of
Write the expression to obtain the final reduced temperature of
Here, critical temperature of
Write the expression to obtain the initial reduced temperature of
Here, critical temperature of
Write the expression to obtain the initial and final reduced pressure of
Here, critical temperature of
Write the expression to obtain the final reduced temperature of
Here, critical temperature of
Write the expression to obtain the entropy change for
Write the expression to obtain the entropy change for
Here, number of moles of
Write the expression to obtain the surrounding entropy change
Here, surrounding heat is
Write the expression to obtain the entropy generation
Write the expression to obtain the energy destroyed during a process
Here, initial temperature is
Conclusion:
Substitute 160 K for
Substitute 5 MPa for
Substitute 200 K for
Refer Figure A-30, “Generalized entropy departure chart”, obtain the value of
Substitute 160 K for
Substitute 5 MPa for
Substitute 200 K for
Refer Figure A-30, “Generalized entropy departure chart”, obtain the value of
Substitute
Substitute 0.75 kmol for
Substitute –4,745 kJ for
Substitute
Thus, the entropy generation is
Substitute 293 K for
Thus, the energy destroyed is
Want to see more full solutions like this?
Chapter 13 Solutions
EBK THERMODYNAMICS: AN ENGINEERING APPR
- Determine the entropy change of 1.5 moles of ammonia that is heated from 180°C to 750°C. The system operates at an atmospheric pressure on a steady flow process.arrow_forwardCase 1: 1 kg of water initially at 20 C is heated to 100 C by contact with a heat reservoir at 100 C. Assume Cp for water is constant at 4.2 kJ/ kg *K. What is the entropy change of the water? What is the entropy change of the reservoir? What is ΔSTotal ? Case 2: Now, as an alternative, 1 kg of water at 20 C is first heated to 60 C by contact with a heat reservoir at 60 C, and then this water is heated from 60 C to 100 C by contact with a heat reservoir at 100 C. What is the entropy change of the water? What is the entropy change of the reservoir? What is ΔSTotal ?arrow_forwardMethane, flowing at 17.5 kmol/hr, is compressed in a steady-state adiabatic compressor (87%efficient) from 0.1013 MPa and -240°F to 0.4 MPa. What is the work required in kJ per mole ofmethane? What is the work required in kW? What is the rate of entropy generation in kJ/K hr?Use the provided diagramarrow_forward
- Write down the equation for macroscopic entropy change ∆S in a process taking a system between equilibrium states a and b in terms of infinitesimal heat flow and the temperature at which it occurs.arrow_forwardA mixture of hydrocarbon gases is composed of 60 percent methane, 25 percent propane, and 15 percent butane by weight. This mixture is compressed from 100 kPa and 20°C to 1400 kPa in a reversible, isothermal, steady-flow compressor. Calculate the work and heat transfer for this compression per unit mass of the mixture. The universal gas constant is R₁ = 8.314 kPa-m³/kmol-K. Use the table containing the molar mass, gas constant, and critical-point properties. P₂ 60% CH4 25% C₂H₂ 15% C₂H10 (by mass) 100 kPa 20°C W The work input for this compression per unit mass of the mixture is The heat transfer for this compression per unit mass of the mixture is kJ/kg. kJ/kg.arrow_forwardRequired information Problem 07.021 - DEPENDENT MULTI-PART PROBLEM - ASSIGN ALL PARTS NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. During the isothermal heat addition process of a Carnot cycle, 700 kJ of heat is added to the working fluid from a source at 400°C. Problem 07.021.b - Entropy change of source in a heat addition process Determine the entropy change of the source. (You must provide an answer before moving on to the next part.) The entropy change of the source is KJ/K.arrow_forward
- Arrange the given systems in order from highest entropy to lowest entropy. liquid salt water at -10°C spring water vapor at 100°C Highest entropy Lowest entropy Answer Bank other entropies equal all entropies equal solid spring water at -2°Carrow_forwardConsider an ideal gas (pv = RT ) and address the following. Your answers may contain p, v, T, cp, R. a) Find the relationship describing how the enthalpy varies with pressure at a constant temperature, i.e.,determine the functional form of (∂h/∂p)T b) Find a relationship for how the entropy varies with pressure at a constant temperature, i.e.,(∂s/∂p)T For the next two parts, now consider a gas that is described by the following truncated virial equation-of-state:Z = (pv/RT) = 1 + B′p + C′p2 where B′ and C′ and constant, temperature-independent parameters. Address the following. Your answers may contain p, v, T, cp, B′, C′. c) Find a relationship for (∂h/∂p)Td) Find a relationship for (∂s/∂p)Tarrow_forwardWhat is entropy and its application?arrow_forward
- 2. In a power station, saturated steam is generated at 252°C by transferring heat from the hot gases gener- ated in the combustion chamber. The gases are cooled from 1100°C to 550°C during transferring the heat for steam generation. Determine the increase in total entropy of the combined system of gas and steam and increase in unavailable energy on the basis of one kg of steam generated. Assume water enters the boiler at saturated condition and leaves as saturated steam. [Ans. 1.99 kJ/K ; 597 kJ/kg of steam formed]arrow_forward(a) How much heat flows from 1.00 kg of water at 38.2°C when it is placed in contact with 1.00 kg of 22°C water in reaching equilibrium? (b) What is the change in entropy due to this heat transfer? (c) How much work is made unavailable, taking the lowest temperature to be 22°C?arrow_forwardA partition separating a chamber into two compartments is removed. The first compartment initially contains oxygen at 600 kPa and 100°C; the second compartment initially contains nitrogen at the same pressure and temperature. The oxygen compartment volume is twice that of the compartment containing nitrogen. The chamber is isolated from the surroundings. Determine the change of entropy associated with the mixing of the O2 and N2. HINT: Assume that the process is isothermal.arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY