Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two “off the shelf” units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow rate increase of the gases before the chiller inlet. The results show that no risk of cold end corrosion within the chiller heat exchanger exists. In addition, crystallization is not an issue during system operation. Accounting for the electricity and the cooling produced and disregarding the remaining thermal energy, the second strategy is preferred and yields an overall estimated efficiency of 71.7%.     

Dehydrogenation of 11α‐hydroxy‐16α, 17‐epoxyprogesterone by encapsulated Arthrobacter simplex cells in an aqueous/organic solvent two‐liquid‐phase system

BACKGROUND: Arthrobacter simplex cells immobilised in sodium cellulose sulfate/poly‐dimethyl‐diallyl‐ammonium chloride microcapsules were used for the microbial dehydrogenation of 11α‐hydroxy‐16α,17‐epoxyprogesterone to 11α‐hydroxy‐16α,17α‐epoxypregn‐1,4‐diene‐3,20‐dione in an aqueous/organic solvent two‐liquid‐phase system, which is a key reaction in the production of glucocorticoid pharmaceuticals. The aim of the study was to establish a suitable aqueous/organic solvent two‐liquid‐phase system for performing semi‐continuous production in an airlift loop reactor by encapsulated A. simplex cells with the addition of suitable surfactants to achieve a higher yield of the product. RESULTS: n‐Hexane was selected as the most suitable organic solvent. In optimised Tween‐80 emulsion feed mode the conversion in the airlift loop reactor was as high as 97.54% when the time of reaction was 2 h, and the reaction time was greatly shortened. In semi‐continuous production the cultivation with immobilised cells was carried out for five batches in total. The conversion in each batch was above 95% and the enzymatic activity still remained quite high after five batches of biotransformation. CONCLUSION: The results showed that performing the conversion by this method shortened the reaction time and increased the productivity, thus demonstrating the great potential of the method for the dehydrogenation of 11α‐hydroxy‐16α,17‐epoxyprogesterone. Copyright © 2008 Society of Chemical Industry     

Heterogeneous kinetics of oxidation of alcohols: PTC techniques

2‐ethyl‐1‐hexanol, n‐heptanol, and n‐hexanol oxidation by potassium permanganate was carried out in a baffled stirred reactor under heterogeneous conditions using phase transfer techniques. Tricaprylylmethylammonium chloride (Aliquat 336) was employed as the phase transfer catalyst. Kinetics of the oxidation was investigated. The rate constants were determined by varying the concentration of the catalyst, the concentration of alcohols and temperature. The rate constants agree well with those obtained under homogeneous conditions for all the three alcohols. The variation in the values under heterogeneous conditions were found to be less than 6 %.     

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根据储层物性参数以及其它影响因素,应用模栩数学建立了孔眯性玻酸盐岩储集层分类数学模型,并进行了纬合评刹分类.此法克服了长期以来储集层分类的片面性和机械性,使分类更加科学。     

Effect of surface properties of different food contact materials on the efficiency of quaternary ammonium compounds residue recovery and persistence

Residues of quaternary ammonium compounds (QACs) remaining after sanitising were evaluated for a number of materials used in food plants. The residues were collected by swabs and measured using a spectrophotometric method. Surface topography and energy affected the QACs recovery. Highest percentage of QACs recovery was achieved for the tile material (102.2%) which had the most hydrophilic properties and least irregularities in surface topology, followed by stainless steel (82.1%). Meanwhile, the lowest recovery occurred in PVC (42.1%) and resin (44.3%) that exhibited hydrophobic characteristics and abrupt changes in height profile in a given surface area. Monitoring of QACs residues deposited on the surfaces after 7 days showed that the recovery of QACs in PVC and resin reduced significantly (P < 0.05), supposing that QACs might be degraded or interacted with the materials. However, no significant changes in residue recovery were observed for tiles and stainless steel surfaces after 7 days.     

Thermally assisted in-line methylation and gas chromatography with statistical data analysis for determination of fatty acid distribution and fingerprinting of plant seeds and oils

Received: 11 October 1999 / Revised version: 7 December 1999     

阳离子表面活性剂对不同纤维吸附性能的研究

讨论了阳离子表面活性剂－双十八烷基二在氯化铵在棉的确良，尼龙和真丝等织物上的吸附量与ｐＨ，浓度，温度等因素条件下的研究，其吸附量顺序为真丝〉尼龙〉棉〉的确良。     

Enhanced conductivity of bacterial cellulose films reinforced with NH4I-doped graphene oxide

ABSTRACT

Bacterial cellulose (BC) films reinforced with reduced graphene oxide (RGO) platelets were investigated to assess their potential application as solid polymeric electrolytes. BC-RGO composites were further doped with NH₄I at different concentrations to evaluate the effect of NH₄I doping on the conductivity. Scanning electron microscopy images confirmed that GO addition did not alter BC coherent three-dimensional morphology. Electrochemical impedance spectroscopy studies revealed that the ionic conductivity increased with the ammonium iodide salt concentration. The highest conductivity found was 1.32 × 10^?4 S/cm for the samples doped with 5% NH₄I, suggesting that BC-RGO can be a promising candidate for electrochemical applications.     

Is the ubiquitous presence of barium carbonate responsible for the poor aqueous processing ability of barium titanate?

The ubiquitous presence of barium carbonate (BaCO₃ – BC) as an impurity in barium titanate (BaTiO₃ – BT) has been pointed out as the main reason for the well-known difficulties found by many investigators when attempting to process BT powders in aqueous media. Different and controversial arguments have been put forward to justify the observed aqueous processing difficulties of BT, but a satisfactory explanation is still to be found. With this aim, a systematic study was here undertaken to shed further light on the solid/liquid interactions occurring at the surface of BC and BT particles and their impact on the dispersion ability of both powders, separately and mixed in certain proportions. Long term colloidal stability and high solid loadings (60 vol.%) were obtained for BC, while colloidal instability and a lower maximum content of solids (50 vol.%) could be achieved for BT. This responds to the question risen in the title.