负载型K2CO3/Al2O3二氧化碳吸收剂的碳酸化反应特性

The carbonation characteristics of K₂CO₃/Al₂O₃ supported sorbent for CO₂ capture was investigated with thermogravimetric apparatus（TGA）,X-ray diffraction（XRD）,scanning electron microscopy analysis（SEM）and N₂ adsorption.The results showed that the carbonation rate of K₂CO₃ before being loaded on Al₂O₃ was slow.However,the K₂CO₃/Al₂O₃ upported sorbent showed excellent carbonation performance.The difference in carbonation behavior between K₂CO₃ nd K₂CO₃/Al₂O₃ supported sorbent was analyzed from the microscopic view.The analytical reagent K₂CO₃ sample was of monoclinic crystal structure and could react quickly with H₂O in the experimental carbonation environment to produce K₂CO₃•1.5H₂O,which was unfavorable to carbonation reaction.When K₂CO₃was loaded on Al₂O₃,the surface area and porosity of the sorbent was improved greatly.So the carbonation properties of the K₂CO₃/Al₂O₃ supported sorbent was also improved.     

负载型钾基CO2吸收剂的结构表征和碳酸化反应特性

The structure identification and carbonation characteristics of several potassium-based supported sorbents for CO₂ capture were investigated with TGA,XRD,XRF,SEM and N₂ adsorption method.Potassium-based sorbents were prepared by impregnation with potassium carbonate on supports,such as cocoanut activated charcoal（AC1）,coal active carbon（AC2）,silica gel（SG）and diatomite（DT）using the iso-volume impregnation method.The results showed that the K₂CO₃ loading amounts of AC1,AC2,SG and DT were 24.1%,22.5%,21.7% and 19.1% respectively.The surface area and pore volume of K₂CO₃/AC1 and K₂CO₃/AC2 were larger than others.In contrast,those of K₂CO₃/DT were small.For K₂CO₃/SG,pore volume was large but surface area was small.K₂CO₃/AC1 and K₂CO₃/AC2 showed excellent carbonation capacity.However,the carbonation capacities of K₂CO₃/SG and K₂CO₃/DT were low.The difference in carbonation capacity of those sorbents were attributed to the difference in pore structure,leading to different supported sorbents.     

Mixed refrigerant composition shift due to throttle valves opening in auto cascade refrigeration system

Auto cascade refrigeration (ACR) cycle with phase separators is widely used in the cryogenic system. The compo-sition of mixed refrigerant has a great effect on the performance of the system. Based on ...     

Effect of Adsorbent Diameter on the Performance of Adsorption Refrigeration

Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.     

采用新型循环方式的硅胶-水吸附式制冷机

The paper proposes an adsorption refrigeration system using silica gel and water as working pair with novel design. In this system, the adsorber, condenser and evaporator are housed in one vacuum chamber, forming an adsorption refrigeration unit. Two such units work alternatively to supply cooling continuously. The construction, parameters of the adsorber, condenser and evaporator and characteristics of the cycle are given. The experimental results demonstrate that the mass recovery process can significantly improve the cooling capacity and COP. The effects of evaporating temperature and cooling water inlet temperature on chiller performance are analyzed. Comparison of the novel system and conventional ones demonstrates that the novel system has a higher performance than the conventional ones with heat recovery process if the problem of cooling loss can be resolved.     

PVAm/PAN复合膜的制备及其对CO2/CH4的分离性能

New polymeric membrane materials——polyvinyl amine (PVAm) with different primary amine contents were synthesized.By covering polyacrylonitrile(PAN) ultrafiltration membranes with PVAm, the PVAm/PAN composite membranes for CO₂/CH₄ separation were prepared. The composite membranes containing more primary amino groups have higher selectivity for CO₂/CH₄.The cross-linking of acid or glutaradehyde could improve the gas permselectivity of the composite membranes. With decreasing CO₂ content in the feed gas, the CO₂/CH₄ separation factor increased.When the feed gas was 25%(vol) CO₂ and 75%(vol) CH₄, the CO₂ permeation rate was 4.1×10^-9cm³(STP) •cm^-2•Pa^-1•s^-1, and the CO₂/CH₄ separation factor was 180.     

带气液分离器自动复叠系统中节流阀开度引起的混合工质浓度偏移(英文)

Auto cascade refrigeration (ACR) cycle with phase separators is widely used in the cryogenic system. The compo-sition of mixed refrigerant has a great effect on the performance of the system. Based on the assumption of infinite volume of phase separator, ACR system with one phase separator is simulated in this paper. The variation of refrigerant composition under different valves opening is obtained. A related experimental system is set up to verify the variation. The result shows that when the valve opening connected to the evaporator increases or the valve opening under the phase separator decreases, the low-boiling component concentration of the working mixture passing through the compressor and condenser increases, while the high-boiling component concentra-tion decreases. Furthermore, the variations of condensation pressure and evaporation pressure under different valves opening are also observed. This paper is helpful to deepen the understanding of ACR system.     

硅酸钠溶液分步碳分制备高纯沉淀氧化硅

By using industrial sodium silicate solution as raw material,high purity SiO₂ powder was successfully synthesized by the split-step carbonation method.The relations between pH value of end point and the removal percentage of impurity at the first carbonation and the purity and yield of product SiO₂ powder at the second carbonation were studied.The SiO₂ powder was characterized by using XRD,SEM,IR and composition analysis.The results showed that when the pH value of end point at the first carbonation was 10.9,the purity of SiO₂ prepared was up to 99.9%.The SiO₂ powder synthesized was amorphous with regular sphere shape,uniform size and no reunion.The reaction mechanism was also discussed.     

碳酸化法制备α-Al(OH)3包覆CaCO3复合晶须

A carbonation process was developed to coat Al(OH)₃ on aragonite whisker. Al(OH)₃ coating was obtained in a suspension,which contained 3Cao·Al₂O₃·6H₂O(C₃AH₆)-NaOH prepared by adding Ca(OH)₂ to NaAlO₂ aqueous solution.The CaCO₃ whiskers coated with fine particles of Al(OH)₃ were prepared by blowing CO₂ gas into the suspension.The formed Al(OH)₃ adhered to the CaCO₃ fibers as the substrate.In order to coat α -Al(OH)₃ on aragonite whisker , the pH value of the solution must be higher than 10.5.The formation of C₃AH₆ and complexation of calcium carbonate molecule with C₃A were the domain factors to get single aragonite phase whisker. Micro-analysis demonstrated that the existence of Al(OH)₃ crystal coating on the surface of aragonite-type calcium carbonate whisker.After the coated whiskers were treated strongly in an ultrasonic water bath.Al(OH)₃ still adhered to the CaCO₃ whiskers well.The reaction mechanism was also mentioned in this paper.     

回料流入口高度对循环流化床提升管流动特性的影响

The axial pressure drop profile and the radial solids distribution were measured in a circulating fluidized bed for evaluating the effects of return gas-solids stream position on the riser flow properties.The saturation carrying capacity of gas for Geldart B typed particles and the flow mode of return gas-solids stream in the bed were discussed.It was found that arranging the inlet at a higher position of the riser would make the bottom bed leaner when U₀ was high and G_s was low.When G_s increased,the longer influenced region of return particles and a small air-staging through lifting the loosening air injection position made the bottom bed become denser significantly.The deceleration and residence of return particles caused a relatively denser but asymmetrical region in the vicinity of inlet.But much more symmetrical solids distribution profile was found in the upper and lower regions far away from the inlet.The effects of inlet height on the flow properties of the riser with air-staging also were analyzed.The secondary air injection below the solids inlet could not cut off the solids exchange in the bed.The bed solids concentration increased when the particles inlet moved to a higher position of the bed when air-staging was adopted.Using CO₂ as tracer,the dispersion of the loop-seal-fluidizing air for transmitting the return particles was investigated.It was found that the loop-seal fluidizing air dispersion rate was low but can be enhanced by the secondary air injection.     

氨制冷技术研究进展

氨具有良好的热物性和传输特性,是CFCs与HCFCs理想的替代工质。本文介绍了当今氨在制冷空调领域应用研究的新技术,包括NH₃/CO₂复叠制冷技术、氨用CO₂载冷技术、NH₃冷水机组等,另外,本文还从安全可靠、高效、小型化和自动化等方面阐述了氨制冷技术的发展趋势。我国氨制冷技术的发展较为缓慢,可靠性和先进性与国外差距较大,必须加强氨制冷技术的研发力度,促进我国氨制冷技术的发展。     

R23/R134a一级分凝和二级分凝自复叠喷射制冷循环性能理论分析

基于非共沸混合工质自复叠原理应用于喷射制冷循环的研究,对一级分凝和二级分凝自复叠喷射循环进行了理论分析,研究了使用R134a/R23非共沸混合工质时制冷剂的配比、冷凝温度和蒸发温度对两种循环性能的影响,结果表明：随着低沸点组分R23质量分数由0.10增至0.20,一级分凝循环喷射器压比在3.4附近变化,而二级分凝循环喷射器压比在1.8附近变化,两种循环COP均增大;随着冷凝温度由18℃升至23℃,一级分凝循环喷射器压比由3.242增至3.792,而二级分凝循环喷射器压比由1.860升至1.867,两种循环COP均降低;随着蒸发温度由-10℃降至-15℃,一级分凝循环喷射器压比由3.454降至2.832,而二级分凝循环喷射器压比由1.870降至1.840,两种循环COP均升高,并且在相同工况下,二级分凝循环COP远高于一级分凝循环;二级分凝循环在喷射器压比为1.8时,可获得-15℃温区的制冷温度。     

自复叠制冷系统压力和组分调节

热气旁通调节可有效排除高压对自复叠制冷系统的危害，但对混合工质的组分没有调节作用。针对三级自复叠制冷系统冷凝压力和排气温度较高的特点，提出了带两路旁通的4种压力和组分调控方式。热气旁通调节时冷凝压力周期性波动变化较大，电磁阀开启较频繁，系统开机70 min后才能达到稳定状态。二级相分离器气相出口旁通调节时冷量损失较严重，低温工质的冷量通过旁通管路排放到膨胀容器。一级相分离器气相出口调节和两个相分离器气相出口同时调节时制冷系统的性能很接近，系统开机30 min后即可达到稳定运行状态。通过对压缩机和蒸发器运行工况检测，一级相分离器气相出口调节和两个相分离器气相出口同时调节为较好的自动复叠制冷系统压力和组分调控方式。     

N_2O跨临界二级蒸气压缩制冷循环及回热特性

为解决CO2跨临界循环能效低、排气压力高的问题,将天然工质N2O用于跨临界循环,建立了相应的理论模型,比较了CO2和N2O用于二级蒸气压缩跨临界循环的性能,并分析了回热效率对于CO2和N2O系统能效Ccop和最优高压侧排气压力的影响。结果表明:N2O用于二级蒸气压缩跨临界制冷循环中的综合性能要优于CO2,在所选定的工况范围内,N2O的Ccop值比CO2最多提高13.3%,最优高压侧排气压力最多降低17.7%。回热效率对于CO2和N2O系统的最优高压侧排气压力几乎没有影响,回热循环对于CO2二级压缩跨临界系统的能效提升更为有利。     

中间完全冷却CO_2跨临界双级压缩节流循环

双级压缩是提高CO2跨临界制冷循环性能系数COP的有效途径,且中间完全冷却形式的性能优于中间不完全冷却形式。对于中间完全冷却CO2跨临界双级压缩节流循环,节流形式有一次节流(STDC循环)和两次节流(DTDC循环)。分析了高压压力和气体冷却器出口温度对STDC循环和DTDC循环的性能影响,并与CO2跨临界单级压缩(STSC)节流循环进行了比较。结果表明:在给定条件下,DTDC循环的COP值最大、STDC循环的最优高压压力值最高;随着气体冷却器出口温度的升高,3个循环的最大COP均减小,最优高压压力均升高,压缩机的等熵效率均降低。对于DTDC和STDC循环,最优中间压力值偏离高压压力与低压压力的几何平均值,但是对系统的性能系数影响不大。     

单机双级滚动活塞压缩机热泵系统的性能特性

将R410A为工质的单机双级滚动活塞压缩机闪发器系统用于房间空调器,能有效地降低排气温度、提升制冷/制热能力,具有显著的节能效果。通过对单机双级滚动活塞压缩机闪发器热泵系统的分析计算,得出压缩机适宜的高低压腔容积比为4/5。对研制出的样机进行了实验研究,结果表明,在蒸发温度为5℃,冷凝温度为35～45℃的工况下,制冷COP_r最高可达3.81,排气温度低于91℃;蒸发温度为-5～-10℃,冷凝温度为40℃时,制热COP_h最高可达3.38,排气温度低于111℃。     

Thermodynamic analysis of absorption refrigeration cycles using ionic liquid + supercritical CO2 pairs

Absorption refrigerators are alternative systems to conventional compression cycles in which the energy necessary for the refrigeration is provided by heating instead of mechanical power. Commercial absorption refrigerators use two absorbent/refrigerant pairs: NH₃-H₂O and H₂O-LiBr. These systems have some limitations due to the difficulty of separating absorbent and refrigerant, the narrow refrigeration temperature range, or the possibility of corrosion and salt deposition. The application of ionic liquids as absorbents with supercritical carbon dioxide as refrigerant can solve some of these problems because separation of ionic liquid from CO₂ is easy due to the negligible vapor pressure of ionic liquids. In this work, suitable ionic liquids-CO₂ pairs have been selected considering their phase equilibrium properties, calculated with the Group-Contribution equation of state developed by Skjold-Jørgensen. The energetic efficiency of the process with ionic liquids has been estimated by calculation of the Coefficient of Performance (COP) of the process. It has been found that the process with ionic liquids has a lower COP than conventional NH₃-H₂O systems due to the necessity of operating with a higher solution flowrate. Nevertheless, near-optimum performance is obtained in a wide range of process conditions.     

Performance analysis of activated carbon + HFC-134a adsorption coolers

The purpose of this paper is to present the results of performance analysis of a heat driven continuous vapor adsorption refrigerator with activated carbon as the adsorbent and 1,1,1,2-tetrafluoroethane (HFC-134a) as the refrigerant. A set of four adsorption cells takes on the role of the mechanical compressor in the conventional vapor compression refrigeration (VCR) system. Three specimens of activated charcoal under various packing densities were investigated. A parametric analysis was carried out with several evaporating, condensing/adsorbing and desorbing temperatures which are typical operating conditions catered to by HFC-134a. A new integrated relative performance evaluation scheme is proposed. It uses the maximum cycle uptake difference as a factor against which the coefficient of performance (COP) and exergetic efficiency are evaluated. It is shown that there is an optimal set of operating conditions wherein the exergetic efficiency is the maximum. A major part of the thermal energy input is for sensible heating of the compressor body.     

CO2/R170混合物作为复叠式制冷系统低温环路制冷剂的性能

针对CO2/R170混合物在复叠式制冷系统低温环路使用的工况，建立了固液平衡和汽液平衡的数学模型，决定了保证混合物在较低温度下不结晶的配比。在一定的配比范围内对混合物进行了循环性能和可燃性分析。研究了混合物配比对循环性能参数和可燃性的影响，以及中间温度在高温环路使用R290、低温环路使用CO2/R170混合物时，复叠式制冷系统整体制冷系数（COP）的变化趋势。研究表明，这种混合物适宜作为复叠式制冷系统低温环路的制冷剂。     

固体吸附制冷系统中的气液回热

对固体吸附制冷系统中的气液回热进行了研究,对回热量在吸附制冷系统中的影响进行了理论分析,并通过试验验证了气液回热对系统产生的积极影响.