q1?RT1ln5-14
p1pq2?cv?T1?T2??RT2ln4p2，p3
??1?q2?1?q1cv?T1?T2??RT2lnRT1ln，
p4p3p1p2
T1?T2p?T2ln4??1p3?1?pT1ln1p2
5-15 ⑴
T1??1940 KT2??660 K??1?⑵
T2?660?1??66%T1?1940
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
p1V1400?0.1??0.445 kgRT10.287?313
m2?p2V2200?0.1??0.238 kgRT20.287?293
?U?m1cv?T?T1??m2cv?T?T2??0T?m1T1?m2T20.445?313?0.238?293??306 Km1?m20.445?0.238
p??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?? pT2?T12?400?2.5?1000 Kp15-17 ⑴
q1?cv?T2?T1??0.723??1000?400??433.8 kJ/kgq2?RT3ln⑵
v11?0.287?400ln??264.3 kJ/kgv310
w?q1?q2?433.8?264.3?169.5 kJ/kg??1?q2264.3?1??39.0%q1433.8
5-18 ⑴
Ws?m?w?m?R?T1?T2???20??1
T2??T1?20???1?20?1.4?1??298??258.2 Km?R0.5?1.4?0.287
??1??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?p?T2?T1?2??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
环境熵变：
?s2?cpln空气熵变：
T2p?Rln2T1p1
?1.005?ln515.51?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
??1??0.2??800????1?1.4?11.4?505.1 K
R?T1?T2?0.2968??800?505.1?w???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/kg?2001000?
排开环境所作的功为作功能力损失（51.2kJ/kg）
?p?T2?T1?2??p1?5-21
n?1n?0.2??800????1?1.2?11.2?611.8 K
R?T1?T2?0.2968??800?611.8?w???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 kJAnq?T0m??s?300?13.94?0.1832?766.1 kJ
?R?T1?T2?1.4?0.287??500?320?ws???180.74 kJ/kg??11.4?15-23 Tp3200.1?s?cpln2?Rln2?1.005?ln?0.287?lnT1p15000.5 ?0.0134 kJ/kg?K
exh1?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
第六章 习题解答 符合！
???v???u???u???v????p???T?p?????????????p?v?p?T?????T?T?T?v???p?T 6-1 ????h???h???p???v????p??????????v?T??????T??v?T??p?T??v?T???p?????v?T
??p???v??R??R?cp?cv?T??T????????R?T?Tv?b??v??p???p?6-2
???p??a?RT?du?cvdT??T??pdv??pdv?dv????2v?v?b????T?v?6-3 ⑴
?u2?u1?T积分：
?11??a????v1v2?
?11???v?1v2??h2?h1?T??p2v2?p1v1??a?ds?⑵
cvR??p?dT??dv?dv?Tv?b??T?v ?Rlnv2?bv1?b
2?s2?s1?T??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?v3
?Tcp?cv?R2?v?b?22a?v?b??21??v?b?RTv3
???p???RT?du?cvdT??T??pdv?cdT??pv???dv??Tv?b?v?????a ?cvdT?2dvv6-4
RT2a?3v?R2ds?cvcvR??p?dT??dv?dT?dv?T?TTv?b??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?v??s?v ??s?v
??s???v???p???0, ???????0, ???0??T?p??s?T??p?T
?q?cvdT?T?6-7
v21RT??p?dv?dv??Tv?b??v
v2?bv1?b
q?RTln?v?b?v?RTln6-8
1??v???v?T???p?T?v?p???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
工程热力学第五版课后习题答案
