工程熱力學(xué)第五版習(xí)題答案

1、5-1t,cT1 T2T15-25-45-5Wot,CQ1第五章習(xí)題解答873 31364.14%8730.641410064.14 kWt,CT11000weW0t,CQ10.61000600 kJ < 700 kJ該循環(huán)發(fā)動(dòng)機(jī)不能實(shí)現(xiàn)qCp T2T1.011000 300707 kJ/kgq2RT3lnPaRT3ln 旦RT3InT -P1P2T23001.41.4 10.287300In -362.8 kJ/kg1000w5 q2707'362.8344.2 kJ/kgQ210.6414100 35.86 kWt,C1000 4005-3wQ11t,C3442 48.68%

2、707_T2 1000 300T1100070%t,cq1 0.7 707 495 kJ/kgQ2263 10000089765 kJ/h2932,cT19.77T2293 263293Q11000002,C2.84 kW9.77 3600100000 kJ/h 器 2778 kW工程熱力學(xué)345-62,c29314.65T2293 2735-75-85-92,c得T,313 KQ2t2, cQ120 10000.455 kW9.77 3600Ti T2120036000.3 5 10000Q1 1 t10000 1Q Q2150007000可逆絕熱壓縮終態(tài)溫度T2T1 pP1可逆過(guò)程Q且 W

3、 1.1WT2T1 1.1m cp In 互pT13000.30.11.1mcvT2 T1Rln止P1=0.00286 kJ/kg.K5-10理論制冷系數(shù):1,c制冷機(jī)理論功率:t220 C15000 kJ/h0.37000 kJ/h22000 kJ/h1.4 11.4410.6K不可逆過(guò)程QU W 01.1 U300 1.1410.6 300421.7K0.11.01嚴(yán)3000.287In 030.1258293 2581257001,c 7.37 36007.374.74 kW散熱量：Q1 Q2125700 4.74 3600142756 kJ/h冷卻水量：m1427564867.2 kg

4、/hch2o t 4.19 7Q15-11 W Q,U, 100 30 70 kJ熱源在完成不可逆循環(huán)后熵增0.026kJ/kg.K則第二個(gè)過(guò)程熱源吸熱：Q2 T Q1 0.0261006000.026115.6 kJ2T工質(zhì)向熱源放熱：W Q2U2115.63085.6 kJ5-12可逆定溫壓縮過(guò)程熵變：sRIn 理 0.287 In10.66 kJ/kg KP10.1可逆過(guò)程耗功：p,0.1w RT； ln 10.287 400 In264 kJ/kgP21實(shí)際耗功：w 1.25w 1.25264330 kJ/kg因不可逆性引起的耗散損失：q w w 33026466 kJ/kg總熵變:q

5、_T。0.66663000.44 kJ/kg K5-13 qCv T2 T1 ， q2Cp T3TCv T2T1T3 T111T2 T11V3 v 1P2 P1 1Pt5-14 qRT1 In -， q? q £ T2P2RT2InPlP3cv T1 T2RT2 In R92 1 P3q1RT1 In 旦P2丄 T2 I n1P3T1In 日P21000 1 墨 700 kJ5-15 T,1940 K , T2660 K1T2T1 6601 66% 1940 W0 Q11000 66%660 kJW0,maxQ1 1TTW W0,max W0700 660 kJ 40 kJ5-16

6、m1PM400 0.10.287 3130.445 kgm2pN 2rt2200 0.10.287 2930.238 kgT T；m>CvT T2miTm2T20.445313 0.238 293m,m20.445 0.238306 K5-17 T2 T1 匹 400 2.5P1P 衛(wèi)亠空°445 °238 °287 306 0.3 MPaV1V20.1 0.1S g ®m2sTPTPm1CpInRln -m2Cp In -RInT1P1PT2P23060.30.4451.01In0.287In -3130.40.2381.01ln 3060.28

7、7.0.3 In0.0093 kJ/K2930.21000 Kq1Cv T2T0.7231000 400433.8 kJ/kgq2RT3In0.287400In1264.3 kJ/kgV310w q1q2433.8264.3169.5 kJ/kg1亞1264.339.0%q1433.85-18 Wsm w mR T1T2 20120 120 1.4 1T2T1298m R0.5 1.4 0.28711.4 1T2T1 E2980.4 1.4229.4 KP1258.2 KR Ti T20.287298 229.40.5 1.4 -1.4 1Wsm w m 134.5 kWn 15-19 E T

8、i 匹Pi3031.3 111.3515.5 K0.1T2T11.3 1.40.2871.3 11.4 1515.5 30350.8 kJ/kg環(huán)境熵變:q 5080.175 kJ/kg KT0290空氣熵變：s CpIn Rln也T1P1515 511.005 ln0.287ln0.127 kJ/kg K3030.1孤立系統(tǒng)熵變：SisoS1S20.175 0.1270.048 kJ/kg K11.4 15-20 T2 T1 -P28000.2 g505.1 KP11R T1 T20.2968800505.1218.8 kJ/kgw11.4 1exu1 eXU2 u1U2 P0V2 V1T0

9、 S2S1Cv T1T2REP02P2RTP1505.1800218.81000.2968167.6 kJ/kg2001000排開(kāi)環(huán)境所作的功為作功能力損失(51.2kJ/kg)1.2 15-21R T1T20.2968800 611.8n11.2 1RT10.2968800 一3 一一0.237 m /kgP11000rt20.2968611.830.908 m/kgP2200CplnTl RlnP2RlnT2RlnT1P11T11.40.2968611.80.2ln0.2968l n1.4 18000.1eXu2u1 u2P0 V2V1 T0S2RT1 T2P0 VV1To s279.3

10、kJ/kgwV2s0.20 kJ/kg KS10.2968800611.8P2P11000.908eXu1T世800 竺"2611.8 K11.4 1132.5 kJ/kg0.237300 0.25-22p1V1200RT1100.287 50013.94 kgmcp T2 T113.941.005600 5001400.7 kJCpln 辛T11.005 ln 6000.1832 kJ/kg K500EXqQ T0ms 1400.7300 13.94 0.1832634.6 kJAnqT0ms300 13.94 0.1832766.1 kJ5-23 wsR T1 T21.4 0.287500 320exh1ex5-24 1.4 1180.74 kJ/kgCp咋 Rln0.0134 kJ/kgexh2h11.005500Wsexh1exh2q2P2P1h2T。320Q1Q1T11.005 In320500s2 s1 Cp