Thermodynamics: An Engineering Approach 8th Edition

Published by McGraw-Hill Education
ISBN 10: 0-07339-817-9
ISBN 13: 978-0-07339-817-4

Chapter 4 - Energy Analysis of Closed Systems - Problems - Page 205: 4-114

Answer

a) $T_1=113.3°C$, $T_3=675°C$ b) $m_{2,L} = 0\ kg$ c) $W_b=218\ kJ$

Work Step by Step

a) Since the initial state is saturated at $P_1=160\ kPa$: $T_1=113.3°C,\ v_{1,L}= 0.001054\ m³/kg,\ v_{1,G} = 1.0915\ m³/kg$ Given the initial masses of 1 kg of liquid and 2 kg of steam: $V_1=m_{1,L}v_{1,L}+m_{1,G}v_{1,G} = 2.184\ m³$ Thus the final volume: $V_3=1.2V_1=2.621\ m³$ and $v_3=\frac{V_3}{m}=0.8736\ m³/kg$ With $P_3=500\ kPa, V_3$, from table A-6: $T_3=675°C$ b) Since $V_2=V_1$ $v_2=\frac{V_1}{m}=0.7280\ m³/kg > 0.37483\ m³/kg=v_{2,g,sat}$ Therefore there's no liquid in the second state: $m_{2,L} = 0\ kg$ c) Since from 1-2 the volume is constant there's no boundary work, hence $W_b=W_{b,2-3}=P_2(V_3-V_2)$ $W_b=218\ kJ$
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