Concept explainers
The state of liquid water is changed from 50 psia and 50°F to 2000 psia and 100°F. Determine the change in the internal energy and enthalpy of water on the basis of the (a) compressed liquid tables, (b) incompressible substance approximation and property tables, and (c) specific-heat model.
(a)
The specific internal energy of water on the basis of the compressed liquid table.
The specific enthalpy of water on the basis of the compressed liquid table.
Answer to Problem 79P
The specific internal energy of water on the basis of the compressed liquid table is
The specific enthalpy of water on the basis of the compressed liquid table is
Explanation of Solution
Determine the change in an initial specific enthalpy of the liquid water.
Here, the specific enthalpy at 50 F temperature is
Determine the specific internal energy of water on the basis of the compressed liquid table.
Here, the initial specific internal energy of water is
Determine the specific enthalpy of water on the basis of the compressed liquid table.
Here, the initial specific enthalpy energy of water is
Conclusion:
From the Table A-4E, “Saturated water”, obtain the value of initial internal energy and enthalpy at temperature 50 F.
Substitute
From the Table A-7E, “Compressed liquid water”, obtain the value of final internal energy and enthalpy at pressure 2000 psia and temperature 100 F.
Substitute
Thus, the specific internal energy of water on the basis of the compressed liquid table is
Substitute
Thus, the specific enthalpy of water on the basis of the compressed liquid table is
(b)
The specific internal energy of water on the basis of the incompressible substance and property tables.
The specific enthalpy of water on the basis of the incompressible substance and property tables.
Answer to Problem 79P
The specific internal energy of water on the basis of the incompressible substance and property tables is
The specific enthalpy of water on the basis of the incompressible substance and property tables is
Explanation of Solution
Determine the specific internal energy of water on the basis of the incompressible substance and property tables.
Here, the initial specific internal energy of water is
Determine the specific enthalpy of water on the basis of the incompressible substance and property tables.
Here, the initial specific enthalpy energy of water is
Conclusion:
From the Table A-4E, “Saturated water”, obtain the value of initial internal energy and enthalpy at temperature 50 F and 100 F.
Substitute
Thus, the specific internal energy of water on the basis of the incompressible substance and property tables is
Substitute
Thus, the specific enthalpy of water on the basis of the incompressible substance and property tables is
(c)
The specific internal energy of water on the basis of the specific heat model.
Answer to Problem 79P
The specific internal energy of water on the basis of the specific heat model is
Explanation of Solution
Determine the specific heat of water.
Here, the specific heat of water is
Conclusion:
From the Table A-3E(a), “Properties of common liquids, solids, and foods”, obtain the value of specific heat of water is
Substitute
Thus, the specific internal energy of water on the basis of the specific heat model is
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Chapter 4 Solutions
EBK THERMODYNAMICS: AN ENGINEERING APPR
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