A 20-ft^3 tank contains ammonia at 20 lbf/in.^2, 80 F. The tank is attached to a line flowing ammonia at 180 lbf/in.^2, 140 F. The valve is opened, and mass flows in until the tank is half full of liquid, by volume at 80 F. Calculate the heat transferred from the tank during this process.

Question

A 20-[latex]ft ^{3}[/latex] tank contains ammonia at 20 [latex]lbf / in .^{2}[/latex], 80 F. The tank is attached to a line flowing ammonia at 180 [latex]lbf / in .^{2}[/latex], 140 F. The valve is opened, and mass flows in until the tank is half full of liquid, by volume at 80 F. Calculate the heat transferred from the tank during this process.

Accepted Answer

C.V. Tank. Transient process as flow comes in.

[latex]m _{1}= V / v _{1}=20 / 16.765=1.193 lbm[/latex]

[latex]m _{ f 2}= V _{ f2 } / v _{ f 2}=10 / 0.026677=374.855 lbm[/latex],

[latex]m _{ g 2}= V _{ g 2} / v _{ g 2}=10 / 1.9531=5.120 lbm[/latex]

[latex]m _{2}= m _{ f 2}+ m _{ g 2}=379.975 lbm \Rightarrow x _{2}= m _{ g 2} / m _{2}=0.013475[/latex]

Table F.8.1, [latex]u _{2}=130.9+0.013475 imes 443.4=136.9 Btu / lbm[/latex]

[latex]u _{1}=595.0 Btu / lbm , \quad h _{ i }=667.0 Btu / lbm[/latex]

Continuity Eq,: [latex]m _{ i }= m _{2}- m _{1}=378.782 lbm[/latex],

From continuity equation

[latex]m _{ i }= m _{2}- m _{1}=379.975-1.193=378.782 lbm[/latex]

Energy eq.: [latex]Q _{ CV }+ m _{ i } h _{ i }= m _{2} u _{2}- m _{1} u _{1}[/latex]

[latex]\begin{aligned}Q _{ CV } &=379.975 imes 136.9-1.193 imes 595.0-378.782 imes 667.0 \&=- 2 0 1 3 3 9 ~ B t u\end{aligned}[/latex]

Question 4.209E: A 20-ft^3 tank contains ammonia at 20 lbf/in.^2, 80 F. The t...

Related Answered Questions