⑵
W0?Q1??1000?66%?660 kJ
?T?600??W0,max?Q1?1?2??1000??1???700 kJ?2000??T1?
?W?W0,max?W0?700?660 kJ?40 kJm1?
5-16
m2?p1V1400?0.1??0.445 kgRT10.287?313
p2V2200?0.1??0.238 kgRT20.287?293
mT?m2T20.445?313?0.238?293T?11??306 Km1?m20.445?0.238
?U?m1cv?T?T1??m2cv?T?T2??0p??m1?m2?RT??0.445?0.238??0.287?306?0.3 MPaV1?V20.1?0.1
?S?m1?s1?m2?s2??Tp?Tp? ?m1?cpln?Rln??m2?cpln?Rln?T1p1?T2p2???3060.3?? ?0.445?1.01?ln?0.287?ln?3130.4??3060.3?? ?0.238?1.01ln?0.287?ln??0.0093 kJ/K2930.2??
T2?T15-17 ⑴
p2?400?2.5?1000 Kp1
q1?cv?T2?T1??0.723??1000?400??433.8 kJ/kgq2?RT3lnv11?0.287?400ln??264.3 kJ/kgv310
⑵
w?q1?q2?433.8?264.3?169.5 kJ/kg
??1?
R?T1?T2??Ws?m?w?m??20??15-18 ⑴
T2??T1?20???1?20?1.4?1??298??258.2 Km?R0.5?1.4?0.287
??1?q2264.3?1??39.0%q1433.8?p?T2?T1?2??p1?⑵
?298?0.41.4?11.4?229.4 K
Ws?m?w?m? ?34.5 kWR?T1?T2?0.287??298?229.4??0.5?1.4???11.4?1
n?1n?p2?T2?T1???p1?5-19
q??1??303????0.1?1.3?11.3?515.5 K
n??1.3?1.40.287cv?T2?T1?????515.5?303?n?11.3?11.4?1 ??50.8 kJ/kg
?s1?q50.8??0.175 kJ/kg?KT0290
T2p?Rln2T1p1
环境熵变：空气熵变：
?1.005?ln?s2?cpln515.51?0.287ln??0.127 kJ/kg?K3030.1
孤立系统熵变：
?siso??s1??s2?0.175?0.127?0.048 kJ/kg?K
?p?T2?T1?2??p1?5-20
w???1??0.2??800????1?1.4?11.4?505.1 K
R?T1?T2?0.2968??800?505.1???218.8 kJ/kg??11.4?1
exu1?exu2?u1?u2?p0?v2?v1??T0?s2?s1??RTRT? ?cv?T1?T2??p0?2?1?p1??p2?505.1800? ?218.8?100?0.2968?????167.6 kJ/kg2001000?? 排开环境所作的功为作功能力损失（51.2kJ/kg）
n?1n1.2?11.2?p?T2?T1?2??p1?5-21
w??0.2??800????1??611.8 K
R?T1?T2?0.2968??800?611.8???279.3 kJ/kgn?11.2?1 RT0.2968?800v1?1??0.237 m3/kgp11000 v2?RT20.2968?611.8??0.908 m3/kgp2200
?s?cpln ?T2pp?RT2?Rln2?ln?Rln2T1p1??1T1p11.4?0.2968611.80.2ln?0.2968ln?0.20 kJ/kg?K1.4?18000.1
exu1?exu2?u1?u2?p0?v2?v1??T0?s2?s1?R?T1?T2??p0?v2?v1??T0?s??10.2968 ???800?611.8??100??0.908?0.237??300?0.21.4?1 ?132.5 kJ/kg ?m?5-22
p1V1200?10??13.94 kgRT10.287?500
Q?mcp?T2?T1??13.94?1.005??600?500??1400.7 kJ?s?cplnT2600?1.005?ln?0.1832 kJ/kg?KT1500
Exq?Q?T0m??s?1400.7?300?13.94?0.1832?634.6 kJ
?R?T1?T2?1.4?0.287??500?320?ws???180.74 kJ/kg??11.4?15-23
Anq?T0m??s?300?13.94?0.1832?766.1 kJ?s?cplnT2p3200.1?Rln2?1.005?ln?0.287?lnT1p15000.5
?0.0134 kJ/kg?Kexh1?exh2?h1?h2?T0?s2?s1??cp?T1?T2??T0?s ?1.005??500?320??300?0.0134?184.92 kJ/kg
?ex?ws180.74??97.7%exh1?exh2184.92
??1?5-24 ⑴
T2?300?20?1??67.3%T1?1000?20
?t?1?⑵
T0300?1??70%T11000
L?Q1??t????1000??0.7?0.673??27 kJ⑶
Q2?Q1?1????1000??1?0.673??327 kJ
?11??11??S?Q1????Q2????T1?T1??T0T2??1?1??1?1 ?1000???327?????0.09 kJ/K9801000300320????
L?T0?Siso?300?0.09?27 kJ
符合！
第六章 习题解答
???v???u???u???v????p???T?p?????????????p?T??v?T??p?T???T?v????p?T 6-1
???h???h???p???v????p??????????v?T??????v?p?v?T??T??T??T???p?????v?T
??p???v??R??R?cp?cv?T??T????????R??T?v??T?p?v?b??p?6-2
???p??a?RT?du?cvdT??T??pdv??pdv?dv????2?Tv?bv?v?????6-3 ⑴
积分：
?u2?u1?T?11??a????v1v2?
?11????v1v2??h2?h1?T??p2v2?p1v1??a?ds?
⑵
cvR??p?dT??dv?dv?T?Tv?b??v
v2?bv1?b
2?s2?s1?T?Rln??p???v???p?cp?cv?T???T??????T?v?T?v??T?p??⑶
??v???p?????????T?v??T?pR??p??????T?vv?b，
??p?????v?T
??p?????v?T
RT2a??p??????2??v?T?v?b?v32
?Tcp?cv??R2?v?b?2RT?v?b?2a?3v?R2a?v?b?1?RTv3
2???p???RT?du?cvdT??T??pdv?cdT??pv???dv??Tv?b?v?????a ?cvdT?2dvv6-4
ds?cvcvR??p?dT??dv?dT?dv?TTv?b??T?v
6-5 dh?Tds?vdp
??h????T??s?p（湿蒸气区T恒定）
??h???p??T?v?????s?T???s?T 6-6
??h???p???p??T?v???????0?s?s??v??v ??s?v
??s???v???p???0, ???????0, ???0??T?p??s?T??p?T
6-7
?q?cvdT?T?v21RT??p?dv?dv?v?b??T?v
v2?bv1?b
q?RTln?v?b?v?RTln6-8
1??v???v??T?p???p???T???v???p???1????????????1??v???T?v??v?p??p?T??T?v???v??p?T
??v?????v?T??p
???p????T?du?cvdT??T??pdv?cdT??pv????dv?T??v?? ???⑴
???v??dh?cpdT??v?T???dp?cpdT??v?T?v?dp?T??p????⑵
⑶
cp??T?cpcv??T??cvds??dp?dv?dp???dv?T??p?vT??v?p?T?vTds?cv??p?dT???dvT?T??v
6-9
工程热力学(第五版)课后习题答案(全章节)
