Concept explainers
a)
The mass of the iron block.
a)
Answer to Problem 158P
The mass of the iron block is
Explanation of Solution
Write the expression for the energy balance equation for closed system.
Here, energy transfer into the control volume is
Write the expression to calculate the mass of the water.
Here, density of the water is
Write the expression to calculate the total work done by the paddle wheel.
Here, rate of paddle wheel by fan is
Conclusion:
Substitute
Here, change in total internal energy for iron is
From the Table A-3E, “the properties of common liquids, solids and foods table”, select the density of water at room temperature as
Substitute
Substitute
From the Table A-3E, “the properties of common liquids, solids and foods table”, select the specific heat at constant pressure at room temperature for water and iron as
Substitute
Thus, the mass of the iron block is
b)
The entropy generation during the process.
b)
Answer to Problem 158P
The entropy generation during the process is
Explanation of Solution
Write the expression for the entropy balance equation of the system.
Here, rate of net entropy in is
Conclusion:
Substitute 0 for
Substitute
Thus, the entropy generation during the process is
Want to see more full solutions like this?
Chapter 7 Solutions
EBK THERMODYNAMICS: AN ENGINEERING APPR
- A 40-kg aluminum block initially at 227°C is brought into contact with a 40-kg block of iron at 50°C in an insulated enclosure. Determine the final equilibrium temperature (in °C) and the entropy change (kJ/K) for each substance and the total for this process. Refer to the tables at the back of the prescribed textbook for the required values.arrow_forwardDetermine the units of the quantity sbar/Ru, where sbar is the molar specific entropy and Ru is the universal gas constant.arrow_forwardAir is expanded from 320 psia and 500°F to 100 psia and 50°F. Assuming constant specific heats, determine the change in the specific entropy of air. Use the table containing the ideal gas specific heats of various common gases. (Round the final answer to five decimal places.) The change in the specific entropy of air is Btu/lbm.R.arrow_forward
- Steam at a temperature of 210°C, has a specific entropy of 7.1167 kJ/kg-K. Determine the specific internal energy in kJ/kg.arrow_forwardDetermine the specific volume, specific entropy and specific internal energy of steam at a pressure of 2MN/m² and with a temperature of 325°Carrow_forwardIf one kg of air initially at a temperature of 165°C and pressure of 7 bar is heated at constant pressure till the volume is doubled. Determine the change of entropy. Take C = 1.005 kJ/kg K, C = 0.718 kJ/kg K. %3D %3Darrow_forward
- 2. Steam at a temperature of 300°C has a specific volume of 0.09765 m3/kg. Determine the pressure, specific internal energy, and entropy.arrow_forwardA piston-cylinder device contains a saturated water. During a constant- pressure process, 538 kJ of heat is transferred to the surrounding air at 23°C. Determine the total entropy generation during this heat transfer process if the change of entropy is - 1.4 kJ/kg. K.arrow_forwardA piston-cylinder device contains 13 kg of refrigerant-134a at 750 kPa and 70 ∘C. The refrigerant is then cooled at constant pressure until it comes to thermal equilibrium with the atmosphere, which is at 20 ∘C. (a). Determine the amount of entropy transfer (S) into the atmosphere. (b). Determine the change of entropy (ΔS) of the refrigerant. (c). Determine the entropy generated (Sgen,univ) in the system's universe.arrow_forward
- Two blocks A (cp=0.9 KJ/kg-K) and B (cp=0.38 KJ/kg-K) which are initially at 95°C and 540°C, respectively are brought together into contact and isolated from the surroundings. They are allowed to reach a final state of thermal equilibrium. Determine the entropy change of each block and of the isolated system. Mass of block A and B are 0.45 kg and 0.9 kg respectively.arrow_forwardA piston/cylinder arrangement contains 2 kg of ammonia at a temperature 132.45 ℃ and a pressure 5 MPa. The piston floats. Heat is added to the system until the temperature of ammonia reaches 416.37 ℃. Is this process reversible in principle? Just answer with one or two sentences, without doing any computations. Determine the change of entropy for ammonia during the process. Use both the tables and correlations. Do you expect a positive or a negative change in entropy? Please, explain [one sentence is enough].arrow_forwardIn an experiment, a certain amount of air is heated at constant pressure from 1.7 m3, 27 0C and 97 kPa to 414 0C. It is then cooled at constant volume back to its initial temperature. Calculate the change specific entropy in the cooling process in the correct unit in SI and 1 decimal place. Take Specific heat at constant pressure and constant volume for air as 1.005 kJ/kg K and 0.717 kJ/kg K respectively. add units.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