高等化工热力学-流体与平衡

第二讲流体与平衡流体的本质化学特性——非极性、极性、缔合、电解质硬球排斥、色散、静电、偶极、四极等作用力几何特性——球形、椭球形、线形、链状、支链键长、键能、键角、二面角、拓扑结构流体的本质流体内密度不是均匀分布的。流体内密度分布与流体的化学特性和几何特性相关密度分布（即流体结构）直接决定流体的性质分子作用——微观结构——宏观性质流体的本质0123450.00.40.81.2(r)/r气体内密度分布液体内密度分布2.04.06.08.010.00.00.51.01.52.02.53.0298K673Kg(r)r(angstrom)流体的经典热力学描述气体——状态方程立方型、多参数状态方程液体——活度系数模型局部组成模型气体混合——混合规则液体混合——偏摩尔性质平均场近似，均相假设，局部组成流体的经典热力学描述经典状态方程：vdW方程、PR方程、BWR方程2RTapVbV()()()RTaTpVbVVbbVb22300062322(/)()(/)(1)exp()pRTBRTACTbRTaaCT流体的经典热力学描述经典活度系数模型：NRTL、UNIQUAC、UNIFAC212112121212212112EGGGxxRTxxGxxG222112121221212212112lnGGxxxGxxG221212212112212122121lnGGxxxGxxG1212exp()G2121exp()G流体的经典热力学描述lnln()2EiiiiiiijjiiiijiiGzxlnxqxqRTxiiijjjxxriiijjjxqxqexp()ijijURT，；UniversalQuasiChemicalActivityCoefficient流体的经典热力学描述ln[1ln()]mmkikmmkmmnnmnQmmmnnnQXQXimiimimiimxvXxvexp()exp()mnnnmnmnUUaRTTUNIFAC热力学性质假定为体系所含基团性质的加和面积分数摩尔分数流体的现代热力学描述不再分气体与液体，而是先从从流体的化学和几何特性出发，确定流体结构（密度分布）；再由流体结构得到体系能量，由此导出各种热力学性质。有坚实的理论基础，可构建预测性模型。流体的现代热力学描述SAFT方程idhsccdispchainddassocAAAAAAAANkTNkTNkTNkTNkTNkTNkTNkT色散分子缔合离子静电链连接理想气体硬球参考偶极-偶极流体混合流体混合的本质是分子作用的非对称,,,,jiiipnTnTpnnGnGnGdnGdTdpdnTpn,,jiiiTpnnMMn流体混合Gibbs-Duhem方程——热力学一致性检验的唯一标准,.iipxTxMMdTdpxdMTpiinMnM,0iiTpxdM流体混合混合热模型E2i(1)HRx[]()jijijijijijijijkkikikijjkikikkikkkbxGGxxGbGxGx/jijijiabT/ijijijabT0iijjiijjaabb流体的相变纯流体的相图自由度与相律流体相变EPVmABCDFGKB－饱和液体Ｆ－饱和汽体ＡＢ、ＦＧ为稳定平衡ＢＣ、ＥＦ为亚稳平衡ＣＤＥ线，为不稳定平衡，实际上，分裂为汽夜两相。流体相变ˆˆˆ...iiifffiii...ˆlnln(/)iiifxfxIIIff因为所以流体相变汽液相变液液相变流体相变完全互溶体系二元相图dewbubbleHexane(1)-triethylamine(2)流体相变流体相变流体相变完全互溶体系二元相图流体相变部分互溶体系二元相图流体相变——溶解平衡IsothermsforCO2absorptiononto[hmim][eFAP]at298.2,323.2and333.2K流体相变——溶解平衡20040060080010000.000.040.080.120.160.200.24absorptiveamountofsulfurintheIL(mmol/g)concentrationofsulfurinthedodecane(ppmw)[BMIM][FeCl4][BMIM][AlCl4][BMIM][Cl][BMIM]CF3SO3]PredictedadsorptionofdibenzothiopheneindifferentILsat298.15K晶体的本质晶体种类体心立方、面心立方、六面体、斜六面体、斜长方体等不同晶面100，110,111，0001，1100表征晶体结构——晶格矢晶胞尺寸、倒格矢、正格矢，密度分布晶体结构体心立方晶体结构面心立方晶体结构晶体结构冰的晶体结构晶—液界面结构体心立方晶—液界面结构面心立方晶—液界面结构晶—液界面结构冰——水界面结构案例分析（一）N，N二乙基乙醇胺(DEEA)+水体系的热力学研究（1）实验测定DEA+水体系的混合热（2）实验测定DEA+水体系的相平衡案例分析（一）0.00.20.40.60.81.0-2200-2000-1800-1600-1400-1200-1000-800-600-400-200Mahamet.al.MayurMundhwaexperimentHE/J.mol-1XDEA0.00.20.40.60.81.0-3000-2500-2000-1500-1000-500298.15K303.15K323.15KHE/J.mol-1XDEEA混合热案例分析（一）P(kPa)x20304050607080901000.1992335.45343.85350.45355.65359.95363.75367.15370.15372.950.1798335.75344.45350.85355.95360.45364.05367.45370.65373.350.1602335.65343.95350.15355.25359.55363.35366.75369.75372.550.1401335.55343.85350.15355.25359.65363.45366.85369.85372.750.1201335.75343.65349.95355.15359.45363.35366.75369.65372.650.0801335.05343.45349.75354.95359.25363.05366.55369.55372.450.04334.85343.25349.65354.85359.15363.05366.45369.55372.35DEEA和H2O在不同压力和组成下的泡点值案例分析（一）101.3kPa60kPa30kPaT/Kx1y1T/Kx1y1T/Kx1y1372.550.00740.0243359.650.00140.0017341.050.006740.00764372.20.02330.0439359.30.00560.0135341.650.01250.01396372.150.04020.0495359.250.01090.0245341.250.015130.02068372.150.07730.0526359.150.02040.0342341.650.028140.02819372.250.13460.0545359.10.03220.0385341.750.045820.03475372.850.33790.0597359.050.05210.0432341.750.055020.03463373.950.50730.0673359.150.07550.0452342.550.05920.03795379.450.72620.1042359.350.1820.0493342.850.08690.04131372.050.114770.05275359.050.114450.04495342.050.117010.04107371.850.213190.05388359.350.209110.04707342.450.210590.04197372.350.352490.05637359.550.337480.05085343.450.342060.05202397.350.897590.21887382.050.904640.21787361.650.870270.21189386.350.830560.1571369.650.807670.12866350.150.760570.10077361.250.569780.07496344.550.502380.07397案例分析（一）本实验W.V.SteeleTp/KpaTp/KpaTp/Kpa362.5512.02332.52.0022409.27747.366378.4522.02346.0944.0031415.70957.801388.0532.02352.1595.3331422.18970.099392.4537.02361.228.0029428.71684.517396.6542.02368.00310.6642435.281101.296404.3552.02373.49613.325441.89120.75411.0562.02379.23316.669448.548143.21416.9572.02383.98619.937455.247169430.25102.02390.25425.037461.988198.45390.22725.011468.775231.99396.54631.178475.597269.96402.90238.576DEEA的饱和蒸汽压案例分析（一）模型选定——NRTL模型jijijEjiikikkGxGxRTGxln()jijiilljljjjijliijjkikkikkjkkkkGxxGxGGxGxGxE2i(1)HRx[]()jijijijijijijijkkikikijjkikikkikkkbxGGxxGbGxGx案例分析（一）jijigRTijijgRTexp()jijijiG/jijijiabT/ijijijabT0iijjiijjaabb案例分析（一）相平衡计算ˆviiiiiypxf汽相假定为理想混合，水的饱和蒸汽压直接取自文献siiipxp案例分析（一）参数拟合exp2EexpE,calc2exp11p{()}{(H-H)}MppENMcalcpHiiiipppFNp，ln(P/kPa)=A+B/(T/K)+C*ln(T/K)+D*(T/K)ABCD-24.8022143.58865.68909-0.00256DEEA的Antoine方程及参数案例分析（一）拟合结果0.00.20.40.60.81.0-2500-2000-1500-1000-500298.15Kexp303.15Kexp323.15KexpHE/J.Mol-1xDEEA0.00.20.40.60.81.0360370380390400410T(K)x(y)DEEA案例分析（一）a12a21b12/Kb21/Kα1.59059.8297388.272441.10.2DEEA+H2O体系NRTL同时回归方程中的参数案例分析（二）Experiments,correlationandpredictiono