可推算非共沸多元混合物临界区饱和蒸气压的新方程

本文根据混合工质假临界温度的推算式,推导出利用各组分等对比态温度的饱和蒸气压计算混合工质的蒸气压的新方程。推算式中的两个与混合物组成及温度有关的系数,可用非临界区用两点文献值标定．用R401系、R404A和 R407系的三元混合工质的文献值与计算值做了比较,泡点压力和露点压力的推算值的绝对偏差平均值小于1．5％。     

多元混合工质泡点和露点的推算研究

本文在对二元和三元混合液的泡点和露点研究基础上,导出了理想混合物的泡点压力和露点压力与组分的关系式,并通过对R401(A/B/C)、R407(A/B/C/D/E)、R409(A/B)等系列三元混合物的研究,推荐了多元混合物泡点压力和露点压力与对比温度的关联式,上述算法和推算式通过多种混合工质的实验值或文献推荐值比较检验,平均偏差在1%以内,个别点的最大偏差也就在2%左右,满足工程使用精度。     

基于自由体积理论及跨接方程的黏度推算模型

结合自由体积理论黏度模型与跨接方程,本文建立了一个适用于从气相到液相且包含临界区在内的黏度推算模型。以水为研究对象,对其对比密度ρ_r(0.01～2.57)、对比温度T_r(0.46～1.12)范围内的黏度进行了计算,计算值与文献实验值的相对偏差绝对平均值为1.81%,近临界区域相对偏差绝对平均值为4.6%。与现有的自由体积理论黏度模型相比,本文建立的黏度推算模型显著提升了近临界区域黏度的计算精度。     

一个新的物质特性参数——构形因子及其应用

本文根据物质分子结构的基本概念和对比态原理提出了一个表征物质特性的新参数——构形因子ζ,其定义为使用对比温度Tr=0.7的饱和液体体积数据,作者计算得到了40种物质的ζ值,该参数具有清晰的物理意义,数值范围比较适宜,规律性也较好.它可用来关联热力学性质和传递性质而具有较好的精度,例如,关联纯物质的第二维里系数时,计算得18种纯物质的压缩因子的平均误差只有0.8％。     

离子对电荷转移配合物[NO2Py]x[C0(mnt)2]的合成、光谱和磁性表征

合成了两种新的离子对电荷转移配合物 [NO2 Py]x[Co(mnt) 2 ],(NO2 Py =1 (4 nitrobenzyl)pyridinium ;mnt=maleonitriledithiolate;x=1or2时分别对应配合物 2和 1) ,并用元素分析和红外光谱、电喷雾质谱和固体反射电子光谱等谱学方法对两种配合物进行了表征。两种配合物在 77K到 30 0K范围内的变温磁化率结果表明 ,配合物 2是抗磁性物质 ,经Pascal′s常数校正后的配合物 1的磁化率遵循改进的Bleaney Bowers方程 ,实验值和理论计算值能很好的吻合 ,非线性最小平方二乘法拟合所得的最佳拟合参数为 :g =2 392 ,2J/k=5 9K和θ=- 4 9K ,一致性因子R=7 2 0 × 10 -9(R=∑(χobsi - χcalcdi ) 2 / ∑(χobsi ) 2 )。     

近临界区表面光散射法乙醇界面性质的实验研究

针对高温及近临界区流体界面性质测量难题,本文研究了表面光散射法在该温度区间流体表面张力和黏度的高精度测量方法。获取了饱和状态下乙醇在温度范围为303 K~T_c内的表面张力和黏度,并利用实验数据分别拟合了对应的van der Waals方程和含临界项的温度倒数多项式方程,在全温度范围内实验值与方程的偏差均在1.5%之内。同时分析了表面光散射法测量流体表面张力和黏度的测量扩展不确定度,当对比温度T_r=T/T_c0.9时,表面张力和黏度的测量不确定度分别为1%和2% (k=2);当对比温度0.90 T_r 0.99时,测量不确定度范围分别为1%~7%和2%~3%(k=2)。     

离子对电荷转移配合物[NO2Py]x[Co（mnt）2]的合成、光谱和磁性表征

合成了两种新的离子对电荷转移配合物[NO2Py]x[Co(mnt)2],(NO2Py=1-(4-ritrobenzyl)pyridinium;mnt=maleonitriledithiolate;x=1or2时分别对应配合物2和1),并用元素分析和红外光谱、电喷雾质谱和固体反射电子光谱等谱学方法对两种配合物进行了表征.两种配合物在77K到300K范围内的变温磁化率结果表明,配合物2是抗磁性物质,经Pascal′s常数校正后的配合物1的磁化率遵循改进的Bleaney-Bowers方程,实验值和理论计算值能很好的吻合,非线性最小平方二乘法拟合所得的最佳拟合参数为g=2.392,2J/k=5.9K和θ=-4.9K,一致性因子R=7.20×10-9(R=∑(χobsi-χcalcdi)2/∑(χobsi     

制冷剂及其混合物黏度的计算

本文在收集了制冷剂R11、R12、1%13、R22、R23、R32、R13B1、R113、R114、R123、R124、R125、R134a、R141b、R142b、R143a、R152a、R227ea、R236ea、R236fa、R245ca、R245fa、R1234yf、R1234ze及其二元和三元混合物黏度数据的基础上,结合自由体积理论和混合法则建立了一种可以计算制冷剂及其混合物黏度的推算模型。对于纯质制冷剂的黏度,模型预测值与实验值之间的相对偏差绝对平均值小于1.5%,最大相对偏差绝对值小于3.1%。对于制冷剂二元和三元混合物的黏度,模型预测值与实验值之间的相对偏差绝对平均值小于3.6%,最大相对偏差绝对值小于7.5%。     

用ICP-AES测定三烷基氧膦(TRPO)-煤油体系中的稀土元素

研究了以乙醇作为稀释剂直接有机溶液ICP-AES进样测定30%三烷基氧膦(TRPO)-煤油体系中的稀土元素。30%三烷基氧膦(TRPO)-煤油含量在4%～20%之间变化时稀土元素的谱线强度变化缓慢。随着水含量在1%～7%内的增加,稀土元素La,Pr,Nd和Sm的谱线强度略有下降,而Ce随着水含量的增加而增加。HNO₃浓度在0.065～0.315 mol·L-1范围内对稀土元素的相对谱线强度的影响不大。同时研究了元素Fe和Zr在该体系中对稀土元素的基体干扰问题,Fe对稀土元素的干扰不显著,但当Zr的浓度大于稀土元素10倍时,稀土元素Ce,Pr和Nd的相对谱线强度受到一定程度的干扰。该方法的应用范围即30%三烷基氧膦(TRPO)-煤油含量在4%～20%为宜,稀土元素La,Ce,Pr ,Nd ,Sm检测限分别为0.012 ,0.040,0.029,0.040,0.021 μg·mL-1,相对标准偏差小于2%;且与湿法消化法相比该方法的相对误差小于3%。该方法与无机消解水溶液进样ICP-AES法相比,该方法操作简单、快速,可以满足分析的要求。     

微孔中简单流体混合物扩散系数的分子动力学模拟与关联

为了了解简单流体混合物在微孔介质中的流动和传递性质 ,对微孔中氩和氪流体混合物的扩散系数进行了计算机模拟和关联模型研究 .运用平衡分子动力学方法模拟了宏量条件下饱和氩流体的扩散系数和恒温氪流体的扩散系数 ,模拟值与文献实验值符合良好 ,从而程序的正确性得到验证 .然后 ,采用类似Bitsanis等人的方法模拟了平板湿壁微孔中氩和氪等摩尔流体混合物在不同对比温度、不同对比密度以及不同对比孔径条件下的扩散系数 ,发现孔径很小的时候扩散系数会急剧的增大 .同时基于这些模拟值 ,参考CE理论和Heyes关系式 ,以对比温度、对比密度以及对比孔径为变量 ,关联出两个简单流体等摩尔混合物在微孔中扩散系数的计算模型 .模型的计算结果与计算机模拟值能够较好地吻合     

TPT2 and SAFTD equations of state for mixtures of hard chain copolymers

We present the second-order thermodynamic perturbation theory (TPT2) and the dimer statistical associating fluid theory (SAFTD) equations of state for mixtures consisting of hetero-nuclear hard chain molecules based on extensions of Wertheim's theory for associating fluids. The second-order perturbation theory, TPT2, is based on the hard sphere mixture reference fluid. SAFTD is an extension of TPT1 (= SAFT) and is based on the non-spherical (hard disphere mixture) reference fluid. The TPT2 equation of state requires only the contact values of the hard sphere mixture site-site correlation functions, while the SAFTD equation of state requires the contact values of site-site correlation functions of both hard sphere and hard disphere mixtures. We test several approximations for site-site correlation functions of hard disphere mixtures and use these in the SAFTD equation of state to predict the compressibility factor of copolymers. Since simulation data are available only for a few pure copolymer systems, theoretical predictions are compared with molecular simulation results for the compressibility factor of pure hard chain copolymer systems. Our comparisons show a very good performance of TPT2, which is found to be more accurate than TPT1 (= SAFT). Using a modified Percus-Yevick site-site correlation function SAFTD is found to represent a significant improvement over SAFT and is slightly more accurate than TPT2. Comparison of SAFTD with generalized Flory dimer (GFD) theory shows that both are equivalent at intermediate to high densities for the compressibility factor of copolymer systems investigated here.     

Conversion of low-grade heat from FCC absorption-stabilization system to electricity by organic Rankine cycles: Simulation and optimization

In this study, the organic Rankine cycle (ORC) is applied to be integrated into the fluid catalytic cracking (FCC) absorption-stabilization system to extract and convert the low-grade process heat to electricity. This newly integrated system is simulated by the Aspen Plus software. For the simulation, eleven different dry and isentropic working fluids are selected to investigate the energy conversion performance of the incorporated ORC system. It is found that, the performance depends highly on the operational parameters, such as mass flow rate and the evaporation pressure of the working fluids, outlet temperature of the process stream. After optimization, the working fluids R124 and R227ea are determined to be the best candidates due to their highest output net work in HCT (high critical temperature) and LCT (low critical temperature) working fluids, respectively. A further optimization has been conducted based on the economic evaluations (i.e., electricity production cost (EPC) and total annual profit (TAP)). Results show that, for the HCT working fluids, the use of working fluid of R245fa allows the EPC to be the lowest, while the application of R124 obtains the highest TAP. For the LCT working fluids, R227ea is the best choice due to its lowest EPC and highest TAP.     

二元混合工质的氧化分解机理研究

基于量子化学密度泛函理论对低全球变暖潜值工质R152a与R600a进行了氧化分解机理研究. 通过对它们的主要起始反应路径分析及能量变化情况计算,结果表明：R152a与R600a热分解的起始反应可以分为工质自身热分解和与氧气碰撞分解两类,其中工质自身热分解的反应能垒比工质与氧气反应的能垒高,并且R600a比R152a更容易发生氧化分解;在二者混合后的起始反应阶段,R600a更容易先发生分解,而链式反应中R152a与自由基的反应更占优势;两种工质与自由基的反应大部分为放热反应,可以向反应体系提供热量,促进链式反应的进行. 相关结果可为新型混合工质的氧化分解机理研究提供参考.     

The compressibility theorem for quantum simple fluids at equilibrium

An extension of the compressibility theorem for quantum simple fluids within the pathintegral approach is presented. First, it is demonstrated that in the absence of quantum exchange, the isothermal compressibility can be formulated in an exact manner with the use of the pair radial correlation function of the path-integral centroids corresponding to the particles of the fluid. This adds up to the two known formulations based on the pair correlations between true quantum particles, namely the instantaneous and the pair linear response correlations. To complement this extension, an exact Ornstein-Zernike equation for pair centroid correlations is derived, which permits accurate estimates for the isothermal compressibility to be obtained. Several fluids are studied, new numerical results for the latter quantity are reported to support the theoretical points, and some difficulties present in this sort of calculation are discussed. The systems studied are the following: the quantum hard sphere fluid with and without attractive Yukawa interaction, liquid helium-4 and liquid para-hydrogen. Finally, the possibilities of extending the theorem to deal with quantum exchange are considered, and it is shown that the extension and its computational Ornstein-Zernike scheme also hold for a Bose fluid.     

Shear instability in fluids with a density-dependent viscosity

We present a shear instability, which can be triggered in compressible fluids with density-dependent viscosity at shear rates above critical. The instability mechanism is generic: It is based on density-dependent viscosity, compressibility, as well as flow two-(three-)dimensionality that provides coupling between streamwise and transversal velocity components and density variations. The only factor stabilizing the instability is fluid elasticity. The corresponding eigenvalue problem for a plane Couette flow is solved analytically in the limiting cases of large and small wave numbers.     

不同工质中汽泡周围电场特性研究

为探明外加电场作用下,不同工质对强化沸腾换热的影响,本文采用了FC-72、R11、R113和R123四种工质,定量研究了两相系统中汽泡周围电场分布特性,探讨了工质介电常数对汽泡的作用规律．结果表明:随着工质介电常数的增加,电场非均匀性增强,电场对汽泡的作用加剧．这为不同工质对EHD沸腾强化效果不同提供了理论依据．     

Thermodynamic perturbation theory for the (12-6-n) fluids

A perturbation method in which attractive forces are taken as perturbation of the repulsive (reference) forces is applied to calculate the thermodynamic properties of (12-6-n) fluids in terms of the properties of hard-sphere fluid. The numerical values of the thermodynamic properties (free energy per particle, compressibility and excess internal energy) for a range of temperature and density are given for (12-6-8) fluids. Further, two perturbation schemes are adopted to evaluate the total radial distribution function using the EXP version of the optimized cluster theory (OCT). The numerical results are reliable as reported at two states (T* = 1·036,ρ* = 0·65 andT* = 0·719ρ* = 0·85) for the (12-6-8) fluid and the Lennard-Jones (12-6) fluid as well.     

制冷空调领域CO_2替代合成工质可行性分析

介绍了天然工质CO2在制冷空调领域里的应用概况,分析比较了CO2与自然工质氨、碳氢化合物作为替代工质的可行性。指出了从对环境的长期影响来考虑,在几种常用的自然工质中,CO2用来替代人工合成工质最具竞争力。针对CO2应用中的问题,提出了相应的技术措施。     

一个新的方阱流体状态方程

将方阱势能函数视为硬球势的一短程均匀负势的叠加,并由统计力学方法导出了相应的状态方程,这个方程包含两个定标的径向分布函数。利用已知的压缩因子分子动力学模拟数据,回归得到了这两个径向分布函数,从而建立了一个新的方肼流体状态方程。它的吸引项要比Alder等人回归得到的简单得多,与方阱流体压缩因子的MD数据一致性也更好,特别是在高密度区域。