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Humidity Range (humidity + range)
Kinds of Humidity Range Selected AbstractsLarge-Scale Synthesis of Long Crystalline Cu2-xSe Nanowire Bundles by Water-Evaporation-Induced Self-Assembly and Their Application in Gas SensingADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Jun Xu Abstract By a facile water evaporation process without adding any directing agent, Cu2-xSe nanowire bundles with diameters of 100,300,nm and lengths up to hundreds of micrometers, which comprise crystalline nanowires with diameters of 5,8,nm, are obtained. Experiments reveal the initial formation/stacking of CuSe nanoplates and the subsequent transformation to the Cu2-xSe nanowire bundles. A water-evaporation-induced self-assembly (WEISA) mechanism is proposed, which highlights the driving force of evaporation in promoting the nanoplate stacking, CuSe-to-Cu2-xSe transformation and the growth/bundling of the Cu2-xSe nanowires. The simplicity, benignancy, scalability, and high-yield of the synthesis of this important nanowire material herald its numerous applications. As one example, the use of the Cu2-xSe nanowire bundles as a photoluminescence-type sensor of humidity is demonstrated, which shows good sensitivity, ideal linearity, quick response/recovery and long lifetime in a very wide humidity range at room temperature. [source] DEHYDRATION CHARACTERISTICS OF PAPAYA (CARICA PUBENSCENS): DETERMINATION OF EQUILIBRIUM MOISTURE CONTENT AND DIFFUSION COEFFICIENTJOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2009R. LEMUS-MONDACA ABSTRACT This study determined the drying kinetics behavior of papaya at different temperatures (40, 50, 60, 70 and 80C). Desorption isotherms were determined at 5, 20 and 50C over a relative humidity range of 10,95%. The Guggenheim, Anderson and de Boer models were found to be suitable for description of the sorption data. The samples reached equilibrium moisture of 0.10 ± 0.01 g water/g dry matter. Fick's second law model was used to calculate the effective diffusivity (6.25,24.32 × 10 - 10 m2/s). In addition, experimental data were fitted by means of seven mathematical models. The kinetic parameters and the diffusion coefficient were temperature-dependent and were evaluated by an Arrhenius-type equation. The modified Page model obtained the best-fit quality on experimental data according to statistical tests applied. PRACTICAL APPLICATIONS The main utility of this study is the application of both different empirical models and the diffusional model in tropical fruits' dehydration, which can be considered a basis for a very accurate estimation of drying time and the optimization of the same process. Two newly mathematical models are proposed in this study, through which a good fit on the data of experimental moisture content was achieved. The study of drying of papaya cultivated in Chile engages a great technological interest, because this product is widely used in the development of different products such as candying, canning, juice, syrup and marmalade. In addition, papayas cultivated in Chile, along with other tropical fruits cultivated in Brazil, Colombia and the Caribbean, have become especially important in the exportations of these countries. The major markets for these products include the U.S.A., the European Community and Asia. [source] Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity rangeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Guillaume Frutsaert Abstract New alternating copolymers comprising a chlorotrifluorinated backbone and imidazole-terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton-conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three-step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI-alt-CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi-alt-CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi-alt-CTFE) with sPEEK lies in the range of 4,10 mS cm,1 at 40,70 °C and, for blend membranes rich in poly(Imi-alt-CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223,231, 2010 [source] Microstructure and humidity sensitive properties of MgFe2O4 ferrite with Ni and Mn substitutionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004E. Rezlescu Abstract It was studied the effect of manganese and nickel ions on the microstructure and humidity sensitivity of the electrical resistivity of Mg ferrite. The humidity sensitivity depends on composition. The MgMn0.2Fe1.8O4 is sensitive in a wide humidity range, between 11% and 85%RH. The other compositions are sensitive at high humidities only, between 43% and 98%. The response time of a.c. resistivity to the humidity variations was measured to be about 120 seconds for all compositions. This sensor element can be used for controlling the humidity in microwave ovens. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Analysis of leakage currents in photovoltaic modules under high-voltage bias in the field,PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2002J. A. del Cueto As photovoltaic modules become more widely disseminated in high-power or utility-power applications, their ability to withstand high voltage relative to ground becomes a reliability issue. Long-term effects of exposure to high-voltage stress in the field are investigated. Starting in early 1998, four commercially available PV modules inaugurated the high-voltage stress test at the Outdoor Test Facility at NREL. Modules representing both crystalline and amorphous silicon technologies were deployed on the high-voltage stress testbed located outdoors in order to simulate and assess operation in high-voltage array configurations. They were biased at positive and negative polarity 600 V at all times,except for 1 min at noon each day, when they were subjected to 2200 V bias,and their leakage currents to ground were monitored continuously. The ubiquitous effects of moisture on leakage conductance are analyzed. Module leakage conductance is found to be thermally activated with a characteristic energy that depends on relative humidity. Separate current paths likely responsible for leakage conductance are analyzed and identified at opposite ends of the relative humidity range. Leakage current data are integrated against time to arrive at accumulated charge due to long-term, high-voltage exposure. Published in 2002 by John Wiley & Sons, Ltd. [source] Re-entrainment of wall deposits from a laboratory-scale spray dryerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2007M. J. Hanus Abstract This work has determined the magnitude of re-entrainment and established the operational parameters that may be manipulated to influence re-entrainment of salt particles for a small-scale spray dryer (Buchi B-290). The wetness of the spray dryer wall deposits was found to significantly influence the magnitude of re-entrainment. It was shown both experimentally and numerically that wet deposits form at low nozzle air-to-liquid ratios (<2000), which form large droplets that dry slowly, while the initial droplet velocity did not have a large influence on wet deposition. Wet deposits form strong liquid and solid bridges, and thus deposits formed from wet particles were difficult to re-entrain. Less than 2% of deposits formed at nozzle air-to-liquid ratios less than 2000 were re-entrained, while 15.4 to 21.2% of dry deposited particles (formed at nozzle air-to-liquid ratios ranging from 2308 to 3409) were re-entrained. The threshold re-entrainment velocity of sodium chloride particles in the Buchi B-290 spray dryer was found to be between 4 and 7.7 ms,1, which is consistent with the lower-end threshold velocities presented in the literature. No significant trend relating relative humidity to the magnitude of re-entrainment was found in the 0.2,7.4% average relative humidity range, suggesting that the adhesive forces in spray dryer wall deposits are fairly constant across this relative humidity range. Decreasing wall deposit wetness through use of high (>2000) nozzle air-to-liquid ratios and use of high main gas velocities increased the re-entrainment of wall deposits in this spray dryer. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||