Concept explainers
A 0.5-m3 rigid tank contains refrigerant-134a initially at 160 kPa and 40 percent quality. Heat is now transferred to the refrigerant until the pressure reaches 700 kPa. Determine (a) the mass of the refrigerant in the tank and (b) the amount of heat transferred. Also, show the process on a P-V diagram with respect to saturation lines.
(a)
The mass of the refrigerant.
Answer to Problem 29P
The mass of the refrigerant is
Explanation of Solution
Write the expression for the energy balance equation.
Here, the total energy entering the system is
Substitute
Here, the mass is
Calculate the specific volume of the refrigerant.
Here, the specific volume of saturated liquid is
Calculate the specific internal energy of the refrigerant.
Here, the specific internal energy of saturated liquid is
Write the expression for mass of the refrigerant.
Here, the initial specific volume is
Conclusion:
From the Table A-12, “Saturated refrigerant-134a” to obtain the value of specific volume of saturated liquid, the specific volume of saturated vapour, the specific internal energy of saturated liquid, and the specific internal energy change upon vaporization of the saturated refrigerant 134a at 160 kPa of pressure as
Substitute
Substitute
Refer to Table A-13, “Superheated refrigerant-134a”, obtain the below properties at the final specific volume
Write the formula of interpolation method of two variables.
Here, the variables denote by x and y are specific volume and internal energy.
Show the specific volume at
S. No |
specific volume, |
Specific internal energy , |
1 | ||
2 | ||
3 | 367.31 |
Calculate final specific internal energy of refrigerant at the final specific volume
Substitute
From above calculation the final specific internal energy of refrigerant at the final specific volume
Substitute
Thus, the mass of the refrigerant is
(b)
The amount heat transfer to a rigid tank.
Answer to Problem 29P
The amount heat transfer to a rigid tank is
Explanation of Solution
Substitute
Thus, the amount heat transfer to a rigid tank is
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Chapter 4 Solutions
Thermodynamics: An Engineering Approach
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