共查询到18条相似文献,搜索用时 109 毫秒
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新型环保制冷剂氟化醚类物质的热力学分析 总被引:7,自引:1,他引:6
本文筛选了可能作为替代制冷剂的氟化醚类(HFEs)纯物质和混合物,然后对这些工质的制冷循环性能进行了热力学分析。分析结果表明:在醚类纯质及混合物中 c-HFE216、 HFE143a、 c-E2-216、 c-HFE216/HFE143a和c-HFE216/c-E2-216适合替代 CFC12和 HFC134a ; HFE125适合替代 CFC115; HFE134、 HFE245cb β和 HFE143/HFE31-10适合替代 CFC114 ; HFE338mf、 HFE245fa、 HFE143、 HPE263fb、 HFE236ea/HPE245fa和 HFE236ea/HFE143有望成为CFC11的替代物。 相似文献
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电子被HF和HCl分子散射总截面的计算 总被引:1,自引:1,他引:0
利用光学势方法计算了能量在10eV—1000eV范围内电子被H、F和Cl原子散射的总截面,并与已有的实验结果和理论计算进行了比较;又利用可加性规则(additivityrule)计算得到了电子被HF和HCl分子散射的总截面,计算结果也与已有的实验结果和理论计算进行了比较 相似文献
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使用abinitio计算HF/LANL2DZ方法优化出了基态KrHF为C∞v结构,而基态KrFH为Cs结构,同时,计算了平衡几何和离解能,并用abinitio计算MP2/LANL2DZ方法计算了谐性力常数。应用多体项展式法导出了KrFH(X1A′)体系的分析势能函数,研究了势能面上的主要特征 相似文献
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二氧化碳-甲烷混合气体水合物四相区实验研究 总被引:1,自引:0,他引:1
以水合物的形式封存CO2和置换海底的天然气(CH4)水合物需要对CO2-CH4混合水合物的四相平衡状态及数据有清楚的了解。本文通过实验和模型计算对不同组分的CO2-CH4混合水合物的较高四相区(Q2)相平衡进行了测定和表述。实验温度范围为273.16~297 15 K,压力范围分为0~10 MPa。四相区的温度压力范围分别是283.51到287.04 K和4.74到8.37 MPa,甲烷的摩尔组份为0~0.225。结果揭示了相平衡温度和压力随着甲烷组分而变化情况以及四相区的范围和临界点,同时还给出了CO2-CH4混合气体水合物在四相状态下的融化开始和融化结束点。实验结果与热力学模型计算得出的CO2-CH4混合气体水合物相平衡结果进行比较,两者很好吻合,四相平衡区域的存在范围得以明确。 相似文献
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范德瓦尔斯分子p—C6H4FCH3...Ar外部振动的共振双光子电离光谱 总被引:1,自引:0,他引:1
利用单色共振双光子电离光谱技术研究了p-C6H4FCH3与Ar形成的范德瓦尔斯分子p-C6H4FCh3...Ar电子太跃迁O带附近的光谱,观察到了许多谱带。分析表明,这些谱带,除来自于甲基CH3内转动跃迁外,都可以归属为Ar相对于p-C6H4FCH3的振动跃迁。在用三维谐湃郛波函数一组合作为基和内德-琼斯作用的基础上,借助量子力学方法计算了p-C6H4FCH3...Ar分子中范德瓦斯振动的能级,计 相似文献
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将光学势方法与可加性规则(additivityrule)相结合,我们计算了能量在10-1000eV范围内正电子被分子(H2,N2,HCl,NH3,CH4,SF6)散射的总截面,计算结果与已有的实验结果进行了比较。 相似文献
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HFC134a/HCFC141b混合气体水合物相平衡特性 总被引:4,自引:0,他引:4
1引言致冷剂气体水合物具有适合空调蓄冷的理想性质,其形成结晶的温度在8~12℃,在结晶形成“暖冰”时,释放较大的反应热(330~380kJ/kg),并且具有较好的传热性能[1~2]。但早期研究的主要是R11和R12的水合物,其致冷剂是典型的大气臭氧层破坏物质,现已受到了严格的限制。研究和开发新型的CFC替代物气体水合物已成为当前的重点[3]。近年来,中国科学院广州能源研究所在国家自然科学基金和广东省科学基金的支持下,展开了对新型致冷剂气体水合物相变蓄冷材料的研究。文献[4]首次报告了对CFC替代物HFC152a/HCFC141b混合气体水… 相似文献
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混合制冷剂气体水合物生成及融解过程实验研究 总被引:6,自引:0,他引:6
1引言城市建筑物中,空调作为最大用电设备之一,夏季占建筑物耗电总量的一半以上,为了缓解高峰用电负荷并有效利用低谷电力,解决峰期用电紧张的矛盾,达到总体节能的目的,空调蓄冷移峰节电技术被认为是实现城市供电平衡和建筑节能的重要手段。作为实用的空调蓄冷技术,最为重要的是其蓄冷材料的相变温度与空调工况相适应,即在5~12℃发生相变,且相变潜热大,传热性能好.氟里昂气体水合物作为蓄冷材料,具有适合空调储冷的理想性质,可使水在8~12℃水合结晶,形成暖冰时释放反应热,其反应热与结冰潜热相当[1]。然而,由于一些氟里昂… 相似文献
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HFC152a/HCFC141b混合气体水合物相平衡特性研究 总被引:4,自引:1,他引:3
1引言气体水合可使水在8—12”C络合结晶形成水合物,同时释放反应热(蓄冷)。其反应热与传热性能均较理想,被认为是理想的空调蓄冷介质山。早期研究的主要是Rll和R12的水合物。由于Rll和R12严重破坏大气臭氧层而受控,因此寻找替代CFC的新型致冷剂气体水合物成为当前的研究重点[‘-‘]。近年来我们根据混合物性能互补原理,提出了利用混合气体水合物构造性能优良的蓄冷材料的设想[‘1。HFC152a和HCFC141b分别是R12和Rll的首选替代物之一。HFC152a是较活跃的致水合物质,但相变温度和压力偏高。而HCFC141b水合物的相变温度… 相似文献
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制冷剂替代物相平衡性质的分子动力学模拟 总被引:1,自引:0,他引:1
本文利用分子动力学模拟算法研究制冷剂替代物的气液相平衡性质。通过将制冷剂替代物作为极性的2CLJ流体处理,建立了针对它们的 2CLJD 势能模型。利用 NPT+Test Particle 算法对五种制冷剂替代物 (HFC-152a,HFC-143a,HFC-134a,HCFC-142b和HFC-227ea)的气液相平衡性质进行了计算,同时验证了计算结果的热力学一致性。模拟结果与 NIST 的 REFPROP 数据库的最大相对偏差在2%以内。 相似文献
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R. K. Zhdanov T. P. Adamova O. S. Subbotin A. A. Pomeranskii V. R. Belosludov V. R. Dontsov V. E. Nakoryakov 《Journal of Engineering Thermophysics》2010,19(4):282-288
The properties of methane + ethane and methane + propane hydrates of cubic structures sI and sII are theoretically investigated.
It is shown that the composition of the formed binary hydrate strongly depends on the percentage of a heavier guest in gas
phase. For instance, for a 1% molar ethane concentration in gas phase, even at a low pressure, ethane occupies 60% large cavities
in the hydrate sII, and as the pressure grows to 100 atm, it occupies 80% large cavities at a low temperature. The tendency
remains the same at a temperature of higher than the ice melting point, but the methane concentration in the hydrate decreases
to 30%. In the structure sI, the influence of the component composition of the gas mixture on that of the formed hydrate is
less evident. However, in this case, calculation showed also that for a 1% molar ethane concentration in gas phase, ethane
molecules occupy from 8 to 10% large hydrate cavities, depending on the pressure. This work is concerned with modeling phase
transitions between cubic structures sI and sII of methane + ethane binary hydrates in view of incomplete occupation of cavities
in the hydrate by guest molecules. For an ethane concentration under 2% in the gas mixture, the structure sII becomes more
thermodynamically stable than the structure sI. However, as the ethane concentration grows to 20% in the equilibrium ice-gas-hydrate
and to 40% in the equilibrium water-gas-hydrate, the structure sI becomes more thermodynamically stable. Hence, for low ethane
concentrations in a gas mixture, the structure sI can be formed only as a metastable phase. Phase equilibria of methane hydrate
sI and mixed methane + propane hydrate sII are considered, depending on the gas phase composition. Similar results are obtained
for this equilibrium; this can evidence simultaneous formation of hydrates sI and sII at low propane concentrations. 相似文献
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T. P. Adamova O. S. Subbotin L. -J. Chen V. R. Belosludov 《Journal of Engineering Thermophysics》2013,22(1):62-68
Phase equilibria in a multicomponent ice-gas mixture-hydrate system are investigated for a mixture of nitrogen, oxygen, and methane, depending on the gas phase composition, pressure, and temperature. Equilibrium compositions of the formed hydrates are found, depending on the gas mixture composition. Calculations show that with increasing concentration ofmethane in gas phase the pressure of hydrate formation gradually decreases. It is shown that this pressure at considerable methane concentrations approximately corresponds to partial pressure of methane in the gas phase. Conditions of hydrate formation are calculated in the range of temperatures from 258 to 273 K, at pressures from 1 to 350 atm. The obtained results are in agreement with the known experimental data for hydrates of pure gases-nitrogen, oxygen, and methane. 相似文献
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Matthew Lasich Deresh Ramjugernath 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(5):83
Clathrate hydrates are an ice-like material consisting of gas molecules confined within cavities in a crystalline water lattice. Phase equilibria of clathrate hydrates systems was described using the statistical mechanical theory of van der Waals and Platteeuw. This theory makes use of the fractional occupancy of cavities within the clathrate hydrate lattice in the determination of chemical equilibria. Classical density functional theory with intermolecular interactions restricted to the first hydration shell was employed to determine the fractional occupancy. In addition to the external field describing the gas-water interactions, the effect of a gravitational field was introduced. The results of the calculations show that although the gravitational potential term may be orders of magnitude smaller than the thermal kinetic energy of the gas species or the hydrogen-bond energy holding the clathrate lattice together, it can nevertheless influence the phase equilibrium of the clathrate hydrate system to some degree. The effect of the magnitudes of both the gravitational potential and the local gravitational field are considered too. 相似文献
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Predicting clathrate hydrate phase equilibria is of interest in the area of natural gas exploitation. This proof of concept study presents the application of a simple lattice gas model and classical density functional theory coupled with van der Waals-Platteeuw theory to predict clathrate hydrate phase equilibria for several different hydrate-forming gas species. The dissociation pressure curve is predicted using adsorption isotherms predicted for the gas species in the crystal hydrate lattice. Comparisons are made between predicted phase equilibria (and other properties) and available experimental data. 相似文献