a)
The exit temperature
a)

Answer to Problem 105RP
The exit temperature is
Explanation of Solution
Write energy balance equation for a closed system of steam.
Here, temperature at inlet and outlet condition is
Write the expression for the dryness fraction at state 2
Here,
Write the expression of the internal energy at state 2
Write the expression of the entropy at state 2
Write the expression of the mass of steam
Here, initial volume of steam is
Write the expression of the mass of air
Here, initial temperature is
Write the expression of the amount of fan work done in 24 min.
Here, change in time is
Write the expression of energy balance equation for a closed system of air.
Here, amount of heat transfer injected to the steam radiator is
Conclusion:
From Table A-1, “molar mass, gas constant, and critical point properties”, Obtain the gas constant
From Table A-3, “properties of common liquids, solids, and foods”, Obtain the specific heat
From Table A-6E, “Superheated water”, at the pressure of
From to Table A-5, “saturated water – pressure table”, obtain the following properties at the pressure of
Substitute
Substitute 0.6376 for
Substitute 0.6376 for
Substitute
0.01388 kg for m,
Calculate the volume of air.
Substitute 283 K for
Substitute
Substitute 12.58 kJ for
Thus, the exit temperature is
b)
The entropy change of the steam.
b)

Answer to Problem 105RP
The entropy change of the steam is
Explanation of Solution
Write the expression the entropy change of the steam.
Conclusion:
Substitute 0.01388 kg for m,
Thus, the entropy change of the steam is
c)
The entropy change of the air
c)

Answer to Problem 105RP
The entropy change of the air is
Explanation of Solution
Write the expression for the entropy change of the air.
Conclusion:
Substitute 98.5 kg for
Thus, the entropy change of the air is
d)
The energy destroyed during the process
d)

Answer to Problem 105RP
The energy destroyed during the process is
Explanation of Solution
For a closed system, write the simplification rate form of the entropy balance for the room.
Here, entropy generation is
Calculate the energy destroyed during the process
Here, dead state temperature is
Conclusion:
Substitute
Substitute 283 K for
Thus, the energy destroyed during the process is
Want to see more full solutions like this?
Chapter 8 Solutions
THERMODYNAMICS(SI UNITS,INTL.ED)EBOOK>I
- Recall that the CWH equation involves two important assumptions. Let us investigate how these assumptions affect the accuracy of state trajectories under the control inputs optimized in (a) and (b). (c.1): Discuss the assumptions about the chief and deputy orbits that are necessary for deriving CWH.arrow_forwardPROBLEM 2.50 1.8 m The concrete post (E-25 GPa and a = 9.9 x 10°/°C) is reinforced with six steel bars, each of 22-mm diameter (E, = 200 GPa and a, = 11.7 x 10°/°C). Determine the normal stresses induced in the steel and in the concrete by a temperature rise of 35°C. 6c " 0.391 MPa 240 mm 240 mm 6₁ = -9.47 MPaarrow_forwardFor some viscoelastic polymers that are subjected to stress relaxation tests, the stress decays with time according to a(t) = a(0) exp(-4) (15.10) where σ(t) and o(0) represent the time-dependent and initial (i.e., time = 0) stresses, respectively, and t and T denote elapsed time and the relaxation time, respectively; T is a time-independent constant characteristic of the material. A specimen of a viscoelastic polymer whose stress relaxation obeys Equation 15.10 was suddenly pulled in tension to a measured strain of 0.5; the stress necessary to maintain this constant strain was measured as a function of time. Determine E (10) for this material if the initial stress level was 3.5 MPa (500 psi), which dropped to 0.5 MPa (70 psi) after 30 s.arrow_forward
- For the flows in Examples 11.1 and 11.2, calculate the magnitudes of the Δ V2 / 2 terms omitted in B.E., and compare these with the magnitude of the ℱ terms.arrow_forwardCalculate ℛP.M. in Example 11.2.arrow_forwardQuestion 22: The superheated steam powers a steam turbine for the production of electrical power. The steam expands in the turbine and at an intermediate expansion pressure (0.1 MPa) a fraction is extracted for a regeneration process in a surface regenerator. The turbine has an efficiency of 90%. It is requested: Define the Power Plant Schematic Analyze the steam power system considering the steam generator system in the attached figure Determine the electrical power generated and the thermal efficiency of the plant Perform an analysis on the power generated and thermal efficiency considering a variation in the steam fractions removed for regeneration ##Data: The steam generator uses biomass from coconut shells to produce 4.5 tons/h of superheated steam; The feedwater returns to the condenser at a temperature of 45°C (point A); Monitoring of the operating conditions in the steam generator indicates that the products of combustion leave the system (point B) at a temperature of 500°C;…arrow_forward
- This is an old practice exam question.arrow_forwardSteam enters the high-pressure turbine of a steam power plant that operates on the ideal reheat Rankine cycle at 700 psia and 900°F and leaves as saturated vapor. Steam is then reheated to 800°F before it expands to a pressure of 1 psia. Heat is transferred to the steam in the boiler at a rate of 6 × 104 Btu/s. Steam is cooled in the condenser by the cooling water from a nearby river, which enters the condenser at 45°F. Use steam tables. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Determine the pressure at which reheating takes place. Use steam tables. Find: The reheat pressure is psia. (P4)Find thermal efficiencyFind m dotarrow_forwardAir at T1 = 24°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects Determine mass flow rate of the moist air entering at state 2, in kg/min Determine the relative humidity of the exiting stream. Determine the rate of entropy production, in kJ/min.Karrow_forward
- Air at T1 = 24°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects Determine mass flow rate of the moist air entering at state 2, in kg/min Determine the relative humidity of the exiting stream. Determine the rate of entropy production, in kJ/min.Karrow_forwardAir at T1 = 24°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects (a) Determine mass flow rate of the moist air entering at state 2, in kg/min (b) Determine the relative humidity of the exiting stream. (c) Determine the rate of entropy production, in kJ/min.Karrow_forwardA simple ideal Brayton cycle operates with air with minimum and maximum temperatures of 27°C and 727°C. It is designed so that the maximum cycle pressure is 2000 kPa and the minimum cycle pressure is 100 kPa. The isentropic efficiencies of the turbine and compressor are 91% and 80%, respectively, and there is a 50 kPa pressure drop across the combustion chamber. Determine the net work produced per unit mass of air each time this cycle is executed and the cycle’s thermal efficiency. Use constant specific heats at room temperature. The properties of air at room temperature are cp = 1.005 kJ/kg·K and k = 1.4. The fluid flow through the cycle is in a clockwise direction from point 1 to 4. Heat Q sub in is given to a component between points 2 and 3 of the cycle. Heat Q sub out is given out by a component between points 1 and 4. An arrow from the turbine labeled as W sub net points to the right. The net work produced per unit mass of air is kJ/kg. The thermal efficiency is %.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





