南昌大学材料热力学答案

Theproblemsofthefirstlaw1.1aleadbulletisfiredatafrigidsurface.Atwhatspeedmustittraveltomeltonimpact,ifitsinitialtemperatureis25℃andheatingoftherigidsurfaceoftherigidsurfaceisneglected?Themeltingpointofleadis327℃.Themolarheatoffusionoftheleadis4.8kJ/mol.ThemolarheatcapacityCPofleadmaybetakenas29.3J/(molK)铅子弹射向一个寒冷的表面。在什么速度必须前往融化的影响,如果它的初始温度是25℃,加热的刚性表面刚性表面被忽视?铅的熔点为327℃。的摩尔熔化热铅是4.8焦每摩尔。摩尔热容CP的铅可能作为29.3j/(摩尔K)Solution:)/(363102.20721]108.4)25327(3.29[2121)(23322smVvnnWQnMvmvWHTCnQQQabsorbmeltingpmeltincreaseabsorb1.2whatistheaveragepowerproductioninwattsofapersonwhoburns2500kcaloffoodinaday?Estimatetheaverageadditionalpowderproductionof75Kgmanwhoisclimbingamountainattherateof20m/min什么是平均功率的生产在一个人谁燃烧2500千卡的食品在一天的瓦特？估计平均加粉生产75公斤人谁是登高山以20米/分的速度Solution)/(24560208.975)/(12160602410467000//)(104670001868.4102500sin3SJthmgPSJtQtWPJQgincreaBurningBurning1.3Onecubicdecimeter(1dm3)ofwaterisbrokenintodropletshavingadiameterofonemicrometer(1um)at20℃.(a)whatisthetotalareaofthedroplets?(b)Calculatetheminimumworkrequiredtoproducethedroplets.Assumethatthedropletsarerest(havezerovelocity)Waterhaveasurfacetensionof72.75dyn/cmat20℃(NOTES:thetermsurfaceenergy(ene/cm2)isalsousedforsurfacetensiondyn/cm)水一立方分米（1立方分米）被分成20℃，直径一微米（1微米）的液滴。（一）什么是液滴的总面积？（b）计算需要产生的液滴的最小工作。假定液滴垫（具有零速度）水具有72.75达因/厘米的表面张力在20℃（注：术语表面能量（烯/厘米2）也可用于表面张力达因/厘米）Solution)(6.436)106103(1075.72)(106)105.0(4)105.0(34)101(232523263631JSWmnSSSingletotal1.4Gaseousheliumistobeusedtoquenchahotpieceofmetal.Theheliumisinstorageinaninsulatedtankwithavolumeof50Landatemperatureof25℃,thepressureis10atm.Assumethatheliumisanidealgas.(a)whenthevalveisopenedandthegasescapesintothequenchchamber(pressure=1atm),whatwillbethetemperatureofthefirstgastohitthespecimen?(b)Astheheliumflows,thepressureinthetankdrops.Whatwillbethetemperatureoftheheliumenteringthequenchchamberwhenthepressureinthetankhasfallento1atm?气态氦被用于骤冷一热的金属片。氦是在存储在隔热的罐体积为50升和25℃的温度下，压力为10个大气压。假设氦是一种理想的气体。（a）该阀打开，气体逃逸到激冷室中（压力=1atm）中，这将是第一气体的打试样的温度时？（b）由于在氦气流，在罐中的压力下降。会是怎样进入骤冷室中的氦气的温度时，在罐中的压力降低到1个大气压？Solution:)(180118298)(1185.229810101325501010101325)5500(1)()(118)101(298)()(0334.0/00KTTTKRRnCWTbKTPPTTAdiabaticapCRP1.5Anevacuated(P=0),insultedtankissurroundedbyaverylargevolume(assumeinfinitevolume)ofanidealgasatatemperatureT0.Thevalveonthetankisoðenedandthesurroundinggasisallowedtoflowsuicklyintot(etankuntilthepressureinsi`ethetankisequalsthepressureoutside.Assumethatnoheatflowtakesplace.Whatisthe0finaltempeturekftèegaSinthetank?Theheatcap!citymfthegas,CpandCveachíaybe(assumedtobec/nsuantpandSvMhint:onewaytoapproachthexroblemistodefinethesystemasthegasendsupinthetank.抽成真空（P=0），辱骂箱由在温度T0的一个非常大的量的理想气体的（假定无限量）包围。水箱上的阀是oðened和周围的气体被允许流动suickly成吨（例如罐，直到压力insi`e罐是等于外界压力。假定没有热流发生。这是the0finaltempeturekf的TEE气？！在罐中的热帽城市MF的气体，Cp和CV每个IAY被（假定为c/nsuantp和SvMhint：接近xroblem的一种方法是定义系统作为气体结束了在罐中。solution0/000/00)0()(TPPTTPPTTAdiabaticPPCRCR1.6Calculatetheheatofreactionofmethanewithoxygenat298K,assumingthattheproductsofreactionareCO2andCH4(gas)[Thisheatofreactionisalsocalledthelowcalorificpowerofmethane]converttheanswerintounitesofBtu/1000SCFofmethane.SCFmeansstandardcubicfeet,takenat298and1atm计算的甲烷与氧气的反应热在298K，假定反应的产物是二氧化碳和甲烷（天然气）[反应的该热也被称为甲烷的低发热量]转换的答案为英制热量单位/1000的SCF联信甲烷。SCF是指标准立方英尺，在298和1大气压采取NOTE:thisvalueisagoodapproximationforthelowcalorificpowderofnaturalgasDATA:)()()(224gOHgCOgCHFOR80.5705.9489.17]/[0298molgKcalHsolution)1000/(9.2610252103048.01101076.191)/(76.191)89.1780.57205.94()2(22333332982982224422SCFBtumolgKcalHHHHHOHCOOCHCHOHCO1.7Methaneisdeliveredat298Ktoaglassfactory,whichoperatesameltingfurnaceat1600K.Thefuelismixedwithaquantityofair,alsoat298K,whichis10%inexcessoftheamounttheoreticallyneededforcompletecombustion(airisapproximately21%O2and79%N2)(a)Assumingcompletecombustion,whatisthecompositionofthefluegas(thegasfollowingcombustion)?(b)Whatisthetemperatureofthegas,assumingnoheatloss?(c)Thefurnaceprocesses2000kgofglasshourly,anditsheatlossestothesurroundingsaverage400000kJ/h.calculatethefuelconsumptionatSTP(inm3/h)assumingthatforgasH1600-H298=1200KJ/KG(d)Aheatexchangerisinstalledtotransfersomeofthesensibleheatofthefluegastothecombustionair.Calculatethedecreaseinfuelconsumptionifthecombustionairisheatedto800K甲烷输送在298K到玻璃工厂，而经营一个熔化炉，在1600K的燃料与空气的量在298K，这是10％的过量理论上所需要的完整的燃烧量（混合时，也空气是约21％的O2和79％N2）（一）假设完全燃烧，什么是烟道气（燃气燃烧以下）的组成？（二）什么是气体的温度，假设没有热损失？（三）炉处理的玻璃2000公斤每小时，并且它的热损失到周围环境中的平均400000千焦耳/小时。在计算STP的燃油消耗（以m3/h）的假设气体H1600-H298=1200KJ/KG（d）一个热交换器安装将一些烟道气的显热的燃烧空气。计算燃料消耗的降低，如果燃烧空气被加热到800KDATASTPmeansT=298K,P=1atm22224ONOHCOCHfor2.82.89.117.1316)/(CmolcalCPSolution)(210448.1125.9100076.191298)/(25.9)]87.012.72(2.843.179.1171.87.13[01.0)(%87.0%%12.72%%43.17%2%%71.8)11.1(221791.1231%22)(0,,222222224KTTTCmolcalXCCbONCOOHCOOHCOOCHaiippp)/(1644)0224.011868.448.11)8001600(48.1125.9189570(102800000)/(189570)298800)](48.1187.8)48.1125.9[(100076.191)()/(87.848.11/]211002.22.816[)()/(