蓄冷空调及气体水合物蓄冷技术

从蓄冷空调的应用背景出发,简述了蓄冷空调技术的发展与现状,并在此基础上详细介绍了气体水合物蓄冷技术,从气体水合物蓄冷工质的选择、气体水合物结晶\熔解特性改善及气体水合物蓄冷装置设计3个方面对目前的研究现状进行了描述,最后提出了一些今后应该重点展开的研究方向     

气体水合物在空调蓄冷中的应用研究进展

介绍了国内外近几年气体水合物蓄冷技术应用研究进展.从节能与环保角度出发,分析了气体水合物作为新型蓄冷工质在空调蓄冷中应用的必要性.从气体水合物相平衡热力学、结晶动力学、数值模拟以及蓄冷装置等方面阐述了气体水合物在空调蓄冷中应用的可行性,为气体水合物蓄冷技术尽快走向实用化提出了研究重点.     

相变蓄冷浆体材料研究进展

相变蓄冷浆体材料具有良好的流动性和高蓄冷密度,既可用作蓄冷材料,也可作为载冷剂来输送冷量,应用前景广阔。相变蓄冷浆体材料包含冰浆、笼型水合物浆体、微胶囊乳液、相变乳状液和微乳液等,其中笼型水合物又包含CO₂水合物、有机制冷剂水合物和季盐类水合物。本文综述了上述相变蓄冷浆体材料的基础物性、制备方法和流动传热特性,并介绍了水合物浆体生成的强化以及浆体流动特性的改善研究,分析比较了几种相变蓄冷材料的优缺点,列举了浆体材料在蓄冷空调系统中的典型应用,并指出了蓄冷技术未来的发展趋势,如尿素–水,乙醇–水和乙二醇–水等自然工质良好的热学性能均为其制备相变蓄冷材料提供了可能。     

蓄冷技术现状及研究进展

阐述了蓄冷技术的发展及其应用进展情况。蓄冷技术根据蓄冷温度区间不同可以应用于蓄冷空调、空气分离、超临界空气储能系统和低温制冷机领域中。不同应用领域采用不同的蓄冷材料。蓄冷空调主要采用水蓄冷、冰蓄冷、共晶盐蓄冷和气体水合物蓄冷等方式;空气分离和超临界空气储能系统的蓄冷材料为热力学性质适宜的显热材料;低温制冷机采用铅等显热蓄冷材料和具有磁相变的磁性材料蓄冷方式。     

相变蓄冷材料及系统应用研究进展

相变蓄冷技术利用相变材料在相变时伴随着的吸热或放热过程对能量进行储存和应用，起到控制温度、降低能耗和转移用能负荷的作用。本文综述了相变温度在25℃以下的相变蓄冷材料及其在不同应用场景的筛选依据，介绍了相变蓄冷材料在食品医疗冷链物流、建筑节能控温与数据中心应急冷却、人体热管理和医疗保健的相变纺织品等领域的应用。从调节相变蓄冷材料相变温度、过冷度、热导率和循环稳定性等方面总结了材料热物性的调控策略，分析了不同调控策略存在的优缺点，指出相变蓄冷系统可通过增强蓄冷系统热导率和强化传热结构来改善普通材料传热性能差的问题。最后从复合相变材料制备到系统设计优化和应用场景拓展等方面对相变蓄冷技术研究方向进行了展望。     

四丁基溴化铵-四氢呋喃系蓄冷水合物

基于二元工质水合物相对单一工质水合物在蓄冷特性方面的优越性,在水合物客体组分总质量分数为31.4%的条件下,实验研究了四丁基溴化铵(TBAB)-四氢呋喃(THF)混合水合物蓄冷特性. 通过改变TBAB-THF组分配比,考察了水合物的诱导时间、近似相变温度、蓄冷面积及释冷面积的变化. 结果表明,TBAB-THF系中TBAB浓度减少使诱导时间增长、温度突变点降低、近似相变温度降低,从而减小了水合物在生长阶段的蓄冷面积,缩短了分解阶段的分解完成时间;TBAB浓度在25.7%~27.4%时,相变温度在6.3~8.0℃之间,与空调冷冻水相近,且释冷面积相对其他浓度较高,可作为蓄冷空调的良好介质.     

四丁基氯化铵水合物的蓄冷特性

探讨了一种新型季铵盐——四丁基氯化铵的水合物作为蓄冷工质的可行性,对其蓄冷特性进行了实验研究:研究了溶液浓度、循环次数及添加成核剂硼砂对四丁基氯化铵水合物的生长特性的影响。实验结果表明:浓度为40%的TBAC溶液相变过程相对稳定,更适合空调蓄冷工况;添加成核剂硼砂使TBAC溶液的相变温度降低了2℃,结晶过冷度减小2℃;经过多次重复水合反应后,溶液在结晶过程中的过冷度减小了1.5℃,相变温度无变化。利用DSC测试得到四丁基氯化铵水合物相变温度为10.41℃,相变潜热为197.707J.g-1。     

气体水合物蓄冷技术研究进展

综述了国内外制冷剂气体水合物蓄冷技术的研究进展。概括描述了制冷剂气体水合物的相平衡热力学、结晶动力学研究，介绍了水合物蓄冷系统及蓄／释冷过程的研究成果：相平衡研究水合物形成的压力、温度条件；动力学研究水合物的生成，包括添加剂和外场等的作用；蓄冷过程研究系统运行可靠性及优化控制。最后简要展望了今后的主要研究方向。     

水合物利用技术应用进展

过去的几十年中,对于水合物的研究不单单集中在抑制天然气水合物的生成上,基于水合物的生成利用技术也得到了广泛的研究。基于水合物的生成利用技术是环保和可持续的新技术,利用不同气体生成水合物相平衡条件的差异,可用于气体分离、置换开采。由于水合物具有较高的气体浓度,可用于气体的存储。利用水合物较高的化解潜热,可将其用于蓄冷。本文综述了国内外水合物技术的研究应用现状,分析了水合物技术在气体分离与存储、溶液浓缩分离、蓄冷、二氧化碳（CO₂）置换开采等领域有前景的研究方向。但是其水合反应速率慢、生成压力高、后期分离困难,极大地限制了水合物利用技术的工业应用。展望了水合物技术未来的研究发展方向,开发安全、高效和环保的水合物促进剂,开发高效水合物反应设备,开发连续水合物工艺,以便早日实现工业应用。     

相变蓄冷材料在冷链物流中的研究进展

综述了相变蓄冷材料在冷链物流中的研究进展;介绍了冷链物流在我国的发展形势;总结了国内外关于相变蓄冷材料在组成成分、方法制备、蓄冷性能及应用效果等方面的研究概况;梳理了关于冷链物流过程中的各种储运设备在结合相变蓄冷材料前后的性能对比,对相变蓄冷材料在冷链物流中的应用发展前景做出了展望。     

Proposing ab initio assisted lattice distortion theory for phase equilibrium: Pure and mixed refrigerant gas hydrates

With promising applications in cold storage and seawater desalination, various refrigerant gas hydrates are experimentally studied for their phase equilibrium behavior; however, the theoretical modeling to predict their formation conditions is under development. Although a high degree of lattice distortion is expected in these gas hydrates due to highly polar and nonspherical molecules of refrigerants, this issue is not addressed in the van der Waals–Platteeuw theory. With this research gap, we formulate a lattice distortion theory for both pure and mixed refrigerant hydrates. For the first time, ab initio methodology comprising the spin-component scaled MP2 method with Dunning's basis set is implemented for estimating cavity potential of refrigerant hydrates. The extent of lattice distortion is documented in terms of reference chemical potential and enthalpy differences, which are obtained by regressing the Holder's equation with the experimental data of refrigerant hydrate formation. A critical observation is made that the reference properties linearly vary with the “Boltzmann weighted energy-well depth” of the guest. Analyzing the accuracy of the model using average absolute relative deviation between experimental and predicted pressure of hydrate formation, the proposed lattice distortion model outperforms the existing thermodynamic models for variety of pure and mixed refrigerant hydrates.     

水合物形态学研究进展

水合物技术在气体分离、气体储存、海水淡化、蓄冷等领域有巨大的应用潜力。研究水合物的生长方式和形态特征在提高水合物储气量、降低水合物开采风险和防止水合物管道堵塞等方面有重要意义。本文从分子尺度的水合物晶格结构、毫米尺度的水合物晶体形态学和厘米尺度的水合物宏观生长形态学三个方面系统回顾了水合物形态学研究进展：总结了不同客体分子生成的不同类型水合物的不同晶格结构;从笼型水合物和半笼型水合物两个方面,阐述了过冷度、液相组成对水合物晶体形态学的影响;从金属表面传热、相界面传质、晶核加入以及促进剂的使用四个方面,介绍了水合物生长形态学的生长方式及其机理。本文总结了形态学研究对水合物技术工业化应用的积极作用并为水合物形态学研究的进一步发展提供参考。     

Phase behavior of gas hydrates in nanoporous materials: Review

A precise understanding of phase behavior for a variety of both artificial and natural processes is essential to achieving scientific and technological goals. There has been growing research interest in gas hydrates confined in nanoporous media aiming to simulate and analyze the unique behavior of natural gas hydrates in sediments. Moreover, the appearance of peculiar properties due to the confinement effect stimulates research on gas hydrate technology for gas separation, such as CO₂ capture from versatile pre/post combustion emissions. In spite of their importance, reliable phase equilibrium data on gas hydrates confined at a nanoscale are scattered throughout the literature, while those in bulk state are abundant. Accordingly, we surveyed the previous studies on the phase behavior of gas hydrates in various nanoporous materials to include and provide valuable information and knowledge for start-up researchers in various gas hydrate fields.     

The use of lipids as phase change materials for thermal energy storage

Phase change materials (PCMs) are substances capable of absorbing and releasing large amounts of thermal energy (heat or cold) as latent heat at constant temperature as they undergo a change in state of matter (phase transition), commonly, between solid and liquid phases. Since the late 1940s, researchers have recognized the potential for phase change materials to play an essential part in energy storage systems and the search for suitable substances has received increasing interest. Currently, the global PCM market is estimated to grow from $ 460 million in 2013 to approximately $ 1.15 billion by 2018. Fats, oils, and their derivatives are diverse in their structures and among the few renewable feedstocks available that have melting and enthalpy profiles among other properties comparable to those of commercial paraffin waxes currently used in PCM applications. This has led to the investigation of triglycerides, fatty acids, esters, alcohols, and other lipid‐based derivatives as potential PCMs and much research examining lipid‐based materials as PCMs has been published. This article gives a brief overview of phase change materials, highlights the various types of lipid substances examined for PCM applications, and suggests potential future areas of study.     

考虑间接换热额外换热温差的间歇过程储热集成

间歇过程流股间换热有直接换热和间接换热两种方式,通过储热介质进行间接换热会产生额外的换热温差。现有的夹点分析方法考虑间接换热额外换热温差后,难以得到经济且可行的储热集成方案。本文在夹点分析的基础上,提出了一种考虑间接换热额外换热温差的间歇过程储热集成方法。该方法首先使用不同的直接换热和间接换热温差进行热级联分析,确定储热集成后的最小冷、热公用工程用量,识别储热位置和储热量,并依据热级联分析结果,建立时间段温焓图确定储热介质温度,得到储热方案。然后,将储热流股转化为放热时间段的冷流股和需热时间段的热流股,进行换热网络综合与优化,得到符合实际应用的储热集成方案。最后,通过经典实例证明了所提方法的可行性和有效性。     

A comprehensive review of the effect of different kinetic promoters on methane hydrate formation

Gas hydrates have recently emerged as a better alternative for the production, storage, and transportation of natural gases. However, factors like slow formation rate and limited storage capacity obstruct the pos-sible industrial application of this technique. Different types of promoters and synergists have been developed that can improve the kinetics and storage capacity of gas hydrates. This review focuses on dif-ferent kinetic promoters and synergists that can be utilized to enhance the storage capacity of hydrates. The main characteristics, structure and the possible limitations of the use of these promoters are likewise portrayed in detail. The relationship between structure and storage capacity of hydrates have also been discussed in the review. Current status of production of gas from hydrates, their restrictions, and future difficulties have additionally been addressed in the ensuing areas of the review.     

Technology readiness level of gas hydrate technologies

Gas or clathrate hydrates are non-stoichiometric crystalline materials known primarily for the operational and safety problems they pose during hydrocarbon processing as well as a potential source of unconventional natural gas. Gas hydrates also have a variety of other applications, mostly representing opportunities for technology development such as gas separations and seawater desalination. This dual nature of gas hydrates is best represented by the two faces of a Janus particle. Although the research on the various gas hydrate-based technologies has been reviewed, the focus has been on the phase equilibrium and kinetic data needed for process design. On the other hand, the status of the technologies in terms of their commercialization has not been methodically assessed. In this work, we employ the nine-level technology readiness level (TRL) tool to classify the various technologies that are based on gas hydrate crystallization. A brief review of the current status of the technologies is presented first, followed by the status of each one on the TRL scale.