基于13X沸石分子筛/MgCl_2的复合吸附剂性能实验研究

复合吸附剂的吸附性能是吸附制冷循环过程中的一个重要参数,基于测试整体成型复合吸附剂吸附性能的需要,本文设计搭建了一种整体成型吸附剂性能测试装置,对复合吸附剂MgCl_2-13X进行了吸附性能测试实验。结果表明:该实验装置中吸附床外侧底部的温度变化速率较接近吸附床内部底部吸附剂的温度变化速率,二者温度变化速率相差0.01~1.9℃/min,整个吸附和脱附过程二者温度的平均值相差约3.24%,能够满足吸附剂性能测试实验的要求。吸附剂性能测试实验及电镜下吸附剂的微观结构表明:浸泡法制备的复合吸附剂的吸附性能与MgCl_2溶液的浓度有关,MgCl_2能够改善13X沸石分子筛的吸附性能,本实验测得当MgCl_2溶液的浓度为15%时所制得复合吸附剂MX3性能最优,其最大吸附量为0.32 g/g,最大吸附速率0.59 g/min,相比单一吸附剂13X沸石分子筛提高了20%。     

双效双重热化学吸附制冷性能实验研究

建立了基于吸附-再吸附原理和内部回热技术的双效双重热化学吸附制冷实验系统,对其可行性及工作性能进行了实验研究。测试结果表明:双效双重热化学吸附制冷热力循环技术用于制冷空调领域是完全可行的,在每次循环过程中由外界热源输入一次高温解吸热可实现四次冷量输出;当采用NiCl2为高温盐吸附剂、MnCl2为中温盐吸附剂、BaCl2为低温盐吸附剂、NH3为制冷剂时,在加热温度为265℃、制冷温度为15℃、冷却温度为30℃的工况下,双效双重热化学吸附制冷循环的COP达到1.1。在此基础上分析了吸附制冷阶段和再吸附制冷阶段冷量输出过程的制冷功率变化特性,发现再吸附过程吸附反应强于吸附反应。     

一种太阳能吸附制冷用复合吸附剂的研究

利用分子筛巨大的比表面积以分子筛为载体通过浸泡CaCl2溶液的方法制备复合吸附剂,在模拟实际使用条件下,对不同浓度CaCl2溶液制备的复合吸附剂的吸附、解吸性能进行了测定.并将吸附解吸性能最好的复合吸附剂在自制的模拟制冷装置上进行了制冷实验.结果表明,复合吸附剂具有良好的吸附、解吸性能,最大吸附量达46.93%,在自制模拟装置上系统COP达0.25,SCP为0.078w/g,符合太阳能吸附制冷的要求.     

以硫化石墨为吸附剂基质的再吸附制冷性能分析

相比于传统的吸附式制冷,再吸附制冷作为一种新型的制冷方式,其结构更加简单,并且其制冷性能系数也比相同条件下的吸附式制冷系统要高,故有较好的应用前景。但受到吸附剂的传热传质性能的限制,难以实现高效的再吸附制冷。本文利用硫化石墨作为吸附剂的基质,对其导热系数以及渗透率进行了测试比较,优选吸附剂。并且针对再吸附制冷系统建立了相关数学模型,分析不同工况条件下吸附剂工质对的性能。对整个再吸附制冷过程进行模拟仿真,从而得到不同工况下的制冷性能。结果表明,采用新型复合吸附剂的再吸附系统,COP最大可达到0.3以上,SCP最大可达到161 W/kg。     

吸附式制冷中对规整复合吸附剂的性能测试

随着新型制冷方式的发展,越来越多的学者专家开始投入到吸附式制冷的研究领域,在吸附式制冷中,吸附剂的传热性能是影响其效率的主要因素之一。为更好的制备规整复合吸附剂有必要对散状吸附剂进行研究。本文就散状吸附剂的性能进行测试分析,设计了一种既适用于散状吸附剂又适合规整复合吸附剂的吸附性能测试系统。同时,对GC、GC10、GC20、GC30、GC40五种规整的复合吸附剂进行了吸附性能测试实验。     

气体的吸附干燥

综述了气体吸附干燥所用主要吸附剂的吸附性能及吸附法干燥气体的工艺原理、工艺流程及其不同的干燥再生方式以及影响吸附干燥的主要因素。     

吸附制冷系统中固化吸附剂性能的实验研究

在吸附制冷系统中,常用的吸附剂为粉末或颗粒形态,吸附剂颗粒之间的热阻和吸附剂与传热面之间的接触热阻很大,而采用固化吸附剂可以有效提高吸附剂的导热性能。本文以硫化膨胀石墨(ENG-TSA)为基质制备了固化活性炭(AC)吸附剂和固化氯化钙(Ca Cl2)吸附剂,针对固化吸附剂设计了无翅片的吸附床结构,并建立了一个低压蒸气驱动的吸附式制冷系统。通过实验对固化吸附剂的性能进行了测试,分析了吸附剂的传热性能、循环时间和蒸发/冷凝温度对吸附制冷系统性能的影响。结果表明:采用AC/ENG-TSA吸附剂,系统COP、SCP和体积制冷密度分别达到0.140,86.1 W/kg和16.11 k W/m~3;采用CaCl_2/ENGTSA吸附剂,系统COP、SCP和体积制冷密度分别达到0.279,288.6 W/kg和54.03 k W/m~3,性能较传统的吸附剂有明显的提高。     

用于吸附单元管的烧结沸石吸附剂的性能强化实验

以填充烧结微米金属-沸石混合吸附剂的吸附单元管为载体,针对填充有不同混合吸附剂的吸附单元管进行了一系列性能试验,并研究分析了吸附单元管在不同热源温度和风速下的制冷特性。结果显示,填充微米铝粉的混合吸附剂吸附单元管的制冷性能最佳,脱附水量比100%分子筛颗粒的要大31.8%,且循环时间缩短了117 min。在一定范围内,热源温度和风速的提高缩短了系统的循环周期,有利于吸附单元管制冷性能的提升。     

ZSM-5沸石在空调应用中的吸附脱附性能研究

针对固体吸附式制冷在空调领域的应用,建立了一套采用ZSM-5沸石-水作为吸附工质对的实验研究系统,对其吸附脱附性能进行了实验研究,得到了吸附脱附性能曲线。比较了不同吸附床温度以及吸附床有无保温情况下,ZSM-5沸石分子筛对水的吸附情况:低温情况对水蒸气的吸附量随吸附时间明显增加,但吸附率逐渐变慢;床温升高,吸附剂达到吸附平衡所需时间缩短,平衡吸附量则有所降低。     

非平衡吸附特征的吸附床传热传质特性

建立椰壳活性炭-甲醇吸附式制冷系统吸附床传热传质数学模型,应用该模型进行具有非平衡吸附特性的吸附床传热传质研究,利用数值方法对数学模型进行求解,讨论了吸附床在冷却过程中吸附剂温度、吸附速率、吸附量、制冷系数以及单位质量吸附剂制冷功率与时间的关系,吸附床在加热过程中吸附剂温度、脱附速率及脱附量与时间的关系.研究结果表明:吸附床在整个吸附过程中的吸附速率存在一个峰值0.001 2 ks/s,吸附床在整个脱附过程中的脱附速率存在一个峰值0.001 7ks/s,吸附剂温度变化率在换热阶段趋于平缓,制冷系数值在吸附阶段近似呈线性增长,而单位质量吸附荆制冷功率在吸附阶段存在一个峰值35 kW/kW.     

变压吸附系统吸附剂吸附容量的实验研究

运用实验的方法对变压吸附系统中吸附剂的吸附容量进行了研究.分析不同因素对吸附剂吸附容量的影响,包括吸附温度、吸附压力,给出吸附容量在这些因素影响下的变化规律,同时比较了不同吸附剂的吸附容量.实验结果可对工业选用吸附剂以及变压吸附系统的优化设计提供必要的数据.     

Experimental investigation on hydrogen adsorption performance of composite adsorbent in the tank with high vacuum multilayer insulation

Hydrogen is one of the main residual gases in the high vacuum multilayer insulated tank. H₂ adsorption performance of the composite adsorbent was investigated by using a test bench, an X-ray diffraction and a scanning electron microscopy.The composite adsorbent is composed of molecular sieve 5A and getter that includes the different proportion of PdO and Ag₂O. The getter shall is laid as flat as possible when fed into the tank. Leakage and outgassing rate can be decreased by 64% after placing getter. The crystal phase structure of PdO and Ag₂O in getter is unchanged by adsorption performance. Experimental results showed that the H₂ adsorption rate is high at the initial stage, and then it starts to become slow during a relatively long period. The type IV isotherms were obtained with these samples, and the H₂ adsorption principle is also discussed. The optimum percentage content of Ag₂O in the getter is 22%. Under the allowed highest pressure, the composite adsorbent that includes 15% Ag₂O, 85% PdO and molecular sieve 5A is preferentially used in the tank interlayer. The experimental results and performance analyses can be used in the design of the high vacuum multilayer insulated tank.     

掺杂改性锂基材料吸附CO2的研究进展

锂基吸附剂因稳定性强、理论吸附量大、吸附温度较高等优点,成为近年来捕获烟道气中CO₂的研究热点。主要论述了熔融盐掺杂、金属阳离子掺杂和其他元素掺杂的锂基材料对CO₂的捕获效果,并比较了它们的相关性能,对开发锂基吸附材料的研究和发展方向进行了展望。     

Removal of phosphate species from solution by adsorption onto calcite used as natural adsorbent

Phosphates are very important basic materials in agricultural and other industrial applications. Phosphorus is often present in low concentrations in wastewater, almost solely in the form of organic and inorganic phosphates (ortho- and poly-phosphates). The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. The usual methods of treatment are either biological or physicochemical by sedimentation. This paper studies the removal of phosphate species by adsorption onto calcite used as natural adsorbent. The phosphate solutions were prepared artificially by adding certain quantities of K2HPO4 in water. The effect of equilibrium pH, phosphate/mineral ratio and contact time was studied. The results showed that pH plays an important role in the removal of phosphate species from solution, with removal being more efficient in the basic pH region. The experimental results also show that adsorption is also efficient for high ratios phosphate/adsorbent. Finally, the adsorption process is time dependent. Based on the experimental results a possible mechanism of phosphate removal onto calcite surface is proposed. As a general conclusion, phosphate species seem to be efficiently removed from solutions using calcite as natural adsorbent. In addition, the adsorption product can be used as fertilizer for acid soils.     

Microcolumn studies of dye adsorption onto manganese oxides modified diatomite

The method described here cannot fully replace the analysis of large columns by small test columns (microcolumns). The procedure, however, is suitable for speeding up the determination of adsorption parameters of dye onto the adsorbent and for speeding up the initial screening of a large adsorbent collection that can be tedious if a several adsorbents and adsorption conditions must be tested. The performance of methylene blue (MB), a basic dye, Cibacron reactive black (RB) and Cibacron reactive yellow (RY) was predicted in this way and the influence of initial dye concentration and other adsorption conditions on the adsorption behaviour were demonstrated. On the basis of the experimental results, it can be concluded that the adsorption of RY onto manganese oxides modified diatomite (MOMD) exhibited a characteristic "S" shape and can be simulated effectively by the Thomas model. It is shown that the adsorption capacity increased as the initial dye concentration increased. The increase in the dye uptake capacity with the increase of the adsorbent mass in the column was due to the increase in the surface area of adsorbent, which provided more binding sites for the adsorption. It is shown that the use of high flow rates reduced the time that RY in the solution is in contact with the MOMD, thus allowing less time for adsorption to occur, leading to an early breakthrough of RY. A rapid decrease in the column adsorption capacity with an increase in particle size with an average 56% reduction in capacity resulting from an increase in the particle size from 106-250 microm to 250-500 microm. The experimental data correlated well with calculated data using the Thomas equation and the bed depth-service time (BDST) equation. Therefore, it might be concluded that the Thomas equation and the BDST equations can produce accurate predication for variation of dye concentration, mass of the adsorbent, flow rate and particle size. In general, the values of adsorption isotherm capacity obtained in a batch system show the maximum values and are considerably higher than those obtained in a fixed-bed.     

Development of microwave assisted zeolite–water adsorption heat pump

A microwave assisted zeolite–water adsorption heat pump system was designed, manufactured and investigated experimentally. The influence of operation time of microwave oven on performance of the adsorption heat pump was studied. The performance criteria: coefficient of performance, specific cooling power and volumetric cooing power, were calculated for the designed and tested adsorption heat pump system. The regeneration of adsorbent bed was achieved very rapidly (35 min) by using microwave heating system. The poor thermal conductivity of adsorbent did not affect the periods of isosteric heating and isobaric desorption processes.     

分形理论在固体吸附式制冷系统中的应用研究

固体吸附式制冷系统中吸附剂一般是多孔介质结构，吸附剂的内部结构特征对传热特性和吸附质的传质特性有直接影响，进而影响吸附解吸时间。本文探讨利用分形理论来分析固体吸附剂的结构特点，为目前通过对吸附剂的固化处理来提高吸附剂的传热速率的处理方法提供理论上的分析，并指出最佳分形维数的分形结构。     

SCB-g-MMA的固相接枝制备及其吸附性能

采用固相接枝法将甲基丙烯酸甲酯(MMA)接枝到碱处理后的甘蔗渣(SCB)表面,得到固相接枝产物甲基丙烯酸甲酯接枝甘蔗渣(SCB-g-MMA),并通过XRD、FTIR、13 C NMR、SEM和BET(Brunauer-Emmett-Teller)测试等方法对其结构进行表征分析。将SCB-g-MMA作为亚甲基蓝(MB)的吸附剂,进行吸附性能研究。结果表明:在室温下,MB初始浓度在50~400mg/L范围内,当吸附剂投加量大于等于10g/L时,溶液pH范围在6~12,吸附时间超过40min,SCB-g-MMA对MB的去除率达到99%;当吸附剂投加量为2.5g/L时,对MB的吸附量可达97.3mg/g。SCB-g-MMA对MB吸附动力学和吸附等温线更符合准二级动力学方程和Freundlich等温吸附模型。     

Study the adsorption of phenol from aqueous solution on hydroxyapatite nanopowders

In this study, the hydroxyapatite (HAp) nanopowders prepared by chemical precipitation method were used as the adsorbent, and the potential of HAp nanopowders for phenol adsorption from aqueous solution was studied. The effect of contact time, initial phenol concentration, pH, adsorbent dosage, solution temperature and adsorbent calcining temperature on the phenol adsorption, and the adsorption kinetic, equilibrium and thermodynamic parameters were investigated. The results showed that the HAp nanopowders possessed good adsorption ability to phenol. The adsorption process was fast, and it reached equilibrium in 2h of contact. The initial phenol concentration, pH and the adsorbent calcining temperature played obvious effects on the phenol adsorption capacity onto HAp nanopowders. Increase in the initial phenol concentration could effectively increase the phenol adsorption capacity. At the same time, increase in the pH to high-acidity or to high-alkalinity also resulted in the increase in the phenol adsorption capacity. Increase in the HAp dosage could effectively increase the phenol adsorption percent. However, the higher calcining temperature of HAp nanopowders could obviously decrease the adsorption capacity. The maximum phenol adsorption capacity was obtained as 10.33mg/g for 400mg/L initial phenol concentrations at pH 6.4 and 60 degrees C. The adsorption kinetic and the isotherm studies showed that the pseudo-second-order model and the Freundlich isotherm were the best choices to describe the adsorption behaviors. The thermodynamic parameters suggested that the adsorption of phenol onto HAp was physisorption, spontaneous and endothermic in nature.     

沙柳活性炭纤维改性及其对铅离子的吸附性能

采用硝酸对自制的沙柳活性炭纤维进行处理来制备改性吸附材,并与未改性活性炭纤维进行对比,借助红外光谱、扫描电镜等方法分析两者的性能及结构差异。在含铅污水的净化试验中,重点对比分析了水溶液pH值对吸附效果的影响,线性吸附等温线及吸附动力学模型拟合的差异及循环再吸附性能。结果表明:经硝酸改性后活性炭纤维的整体形貌保持不变,其表面含氧官能团及微孔数量增多。随着pH值的增大,改性吸附剂对铅离子的吸附量和吸附速率均大于未改性活性炭,用Langmuir吸附等温线模型和准二级动力学模型可以更好地描述此吸附过程,且改性活性炭纤维具有良好的循环再吸附性能。