Experimental investigation and analysis of composite silica-gel coated fin-tube heat exchangers

Desiccant coated heat exchanger provides a promising option for desiccant cooling system, since it can handle sensible load and latent load simultaneously within one component. It is fabricated by coating desiccant material on the surface of conventional fin-tube heat exchanger. In order to enhance the performance of conventional silica gel coated heat exchanger (SGCHE), a novel composite silica gel coated heat exchanger (CCHE) is proposed and fabricated. An experimental setup is built to test and compare the dynamic performance of SGCHE and CCHE. Influences of main operation parameters including water temperatures and inlet air conditions on system performance are analyzed in terms of average dehumidification capacity (D_avg) and thermal coefficient of performance (COP_th). Optimization of cycle switch modes is also discussed. Experimental results show that CCHE has better dehumidification performance compared with SGCHE. In addition, pre-cooling before dehumidification process is found to be advantageous to both D_avg and COP_th.     

Thin-film composite crosslinked polythiosemicarbazide membranes for organic solvent nanofiltration (OSN)

In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoyl chloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement.The membranes exhibited high fluxes toward solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging around 20 L/m² h at 5 bar with a molecular weight cut off (MWCO) of around 1000 g/mol. The PTSC-based thin-film composite membranes are very stable toward polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry.     

A constitutive model for self-reinforced ductile polymer composites

Self-reinforced polymer composites are gaining increasing interest due to their higher ductility compared to traditional glass and carbon fibre composites. Here we consider a class of PET composites comprising woven PET fibres in a PET matrix. While there is a significant literature on the development of these materials and their mechanical properties, little progress has been reported on constitutive models for these composites. Here we report the development of an anisotropic visco-plastic constitutive model for PET composites that captures the measured anisotropy, tension/compression asymmetry and ductility. This model is implemented in a commercial finite element package and shown to capture the measured response of PET composite plates and beams in different orientations to a high degree of accuracy.     

嵌套式复合型材构件制造技术及其专用机床

嵌套式冷轧复合型材构件制造技术包括平整、加强筋成型、第一辊压模具组成型、冲孔、主截面成型、第二辊压模具组的横截面成型、嵌套合抱、第一构件与第二构件嵌套抱合后成为复合型材构件与第三辊压模具组紧贴等工序组成,在冲孔工序之前先完成加强筋成型工序,保证冲孔加工后的孔距尺寸精度,显著提高产品质量;上述所有工序都是设置在同一条生产线上的专用机床连续自动完成,实现了嵌套式冷轧复合型材构件的自动化生产,节约工时,降低产品成本。     

Synthesis of hexacelsian barium aluminosilicate by film boiling chemical vapour process

An original oxide/oxide ceramic-matrix composite containing mullite-based fibers and a barium aluminosilicate matrix has been synthesized by the film boiling chemical vapour infiltration process. Alkoxides were used as liquid precursors for aluminum, silicon and barium oxides. The structure and microstructure of the oxide matrix were characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy and X-ray diffraction. Apart from small residual mullite and amorphous phase amounts, the oxide matrix is composed of the hexacelsian phase, conferring to the material interesting perspectives for high-temperature electromagnetic and structural applications.     

Hydrogen production by electrochemical methanol reformation using alkaline anion exchange membrane based cell

Electrochemical methanol reformation (ECMR) is an alternative promising technology for producing hydrogen at low energy consumption compared to water electrolysis. In this process, solid polymer electrolyte Nafion® is widely employed, due to its superior proton conductivity. However, major limitations are the utilisation of expensive platinum based catalysts, high cost of the above membrane and the crossover of methanol through the polymer electrolyte membrane. In the present work, attempt has been to made to use low cost polymer electrolyte membrane and less noble electro catalyst. A series of Anion Exchange Membranes (AEM) are synthesized from Poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) for its application in ECMR. PPO is successfully made into anion conducting by chloromethylation followed by quaternization. Two AEM's are synthesized by optimizing chloromethylation reaction time to 5 h and quaternization time to 5 and 8 h and are labelled as QPPO (C5, Q5) and QPPO (C5, Q8) respectively. Further, with the view to improve the anion conductivity further, composite AEMs are prepared by incorporating inorganic anion conducting quaternized graphene oxide particles in the matrix of PPO and QPPO (C5, Q8) polymers separately to obtain two polymers PPO/QGO and QPPO/QGO. The anionic conductivity of PPO/QGO and QPPO/QGO polymer is 1.2 × 10⁻⁴ and 1.5 × 10⁻⁴ S cm⁻¹ respectively. Both the membranes are subjected as electrolyte for ECMR application using membrane electrode assembly made by with in house synthesized nitrogen doped graphene supported Pd catalyst (Pd/NG) as anode catalyst and commercial Pt/C as cathode catalyst. The performance of composite membrane was compared with the commercial Fumasep® FAA anion exchange membrane. The polarization studies of ECMR cell with composite membrane shows comparable performance with that of commercial Fumasep® FAA-2 FAA membrane. The durability of the membrane(s) in the electrolysis environment was tested for about 20 h.     

响应曲面法优化电催化降解染料废水工艺的研究

采用中心复合设计的响应曲面法预测电催化降解染料废水的最优条件。具体以Ti/SnO₂-Sb 电极作为阳极，应用响应曲面法研究了pH、施加电压值、电极间距对亚甲基蓝溶液脱色效率的影响。研究结果表明模型拟合精度R²=0.9942，初始pH、施加电压值、电极间距及交互作用对脱色率响应值影响大。模型预测最佳反应条件pH为 6.98，施加电压6.0 V，电极间距为1.01 cm时，脱色效率预测值达到98.68%。采用实验进一步验证该模型，预测最佳条件下三次实验脱色率平均值98.47%。该方法可用于优化电催化降解染料废水的工艺参数，为实际废水处理提供优化方案。     

Fabrication of multi-filler thermoset-based composite bipolar plates for PEMFCs applications: Molding defects and properties characterizations

The bipolar plate (BP) material should possess contradictory properties. They should also manufacture from low-cost methods and materials. In the current investigation, thermoset-based composite materials reinforced with conductive fillers, and the compression molding process is implemented. In addition to fabricating the bipolar plates (BPs) with and without the flowing channels, alleviating the defects during the molding process is performed. The channels are perfectly formed on the plates with the designed depth of 0.65 mm and 0.5 mm of width. In the meanwhile, we alleviate different molding defects, which spoil the surface appearance and part properties. Regarding the physical properties, the water contact angle is measured to be around 85°. The through-plane electrical conductivity of molded plates showed high values up to 38 S/cm, and the interfacial contact resistance measured to be 18–24 mΩ cm². The mean value of the flexural strength of the produced samples was equal to 47 MPa, which is almost twice the DOE target (>25 MPa).     

Facile synthesis of polyoxometalate-based composite with doped ternary NiCoFe cations as electrocatalyst for oxygen evolution reaction

The construction of efficient and low-cost electrocatalysts for oxygen evolution reactions (OER) to replace precious catalysts is a necessity to achieve economic production of hydrogen. Herein, we report an efficient tri-metallic electrocatalysts for the OER that is prepared by incorporate nickel, cobalt and iron cations on Triton X-100/phosphotungstic acid organic-inorganic composite without utilize any binders or energy consumer procedure. Considering to the synergy effect of simultaneous absorption of NiCoFe cations on composite substrate, the as-made tri-metallic catalyst exhibits excellent OER activity with a small overpotential of 210 and 330 mV at a current density of 10 and 100 mA cm^?2, respectively. Moreover, remarkable trends in electrocatalytic activity of mono-, bi- and tri-metallic electrocatalysts at low (10 mA) and high (100 mA) current density are observed. In addition, this new families of non-precious metal catalyst shows long-term durability in 1 M KOH.     

减震隔声降噪地垫的研发

介绍我国分户楼板隔声及其隔声研究现状,详细阐述多层复合结构的减震隔声降噪地垫的结构、性能和安装,减震隔声降噪地垫与木地板配合使用,将其铺装于扫平层的140 mm厚现浇钢筋混凝土楼板之上,经江苏省建工建材检测中心检测,撞击声隔声为61 dB,能很好地满足住宅分户楼板撞击声隔声L'nT,W≤65 dB的要求。