Concept explainers
a)
The mass of the iron block.
a)
Answer to Problem 133P
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 133P
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
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Chapter 7 Solutions
CENGEL'S 9TH EDITION OF THERMODYNAMICS:
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- A 20 kg aluminum block initially at 500 C is brought into contact with a 20 kg block of iron at 100 C in an insulated enclosure. The final equilibrium temperature of the two blocks is 646.51 K. The specific heat of the aluminum block is 0.973 kJ/kgK. The specific heat of the iron block is 0.45 kJ/kgK. What is the total change in entropy of the two blocks during this process in units of kJ/K? Select the answer that is closest to the true value. A) 0.535 B) 0.987 C) 1.473 D) 1.966 Aarrow_forwardDetermine the change in entropy for an ideal gas that undergoes a change in conditions from a temperature of 300 degrees Celsius and a pressure of 1.2 bar to a temperature condition of 500 degrees Celsius and a pressure of 6 bar. it is known that the value of cp/r= 7/2arrow_forward2. 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_forward
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