Papers by Keyword: Water Vapor

Abstract: Electroplating industry has by-products, most of which are harmful. The paper considers the issue of removing aerosol emissions during chrome coating. We developed a droplet separator, which was granted a patent for a useful model. Based on the model, we proposed a stage-by-stage technical procedure for cleaning gas-air mixture to optimize the performance of gas-cleaning equipment during hard chrome coating. We calculated the amounts of water vapor and chromic anhydride which is released during chrome plating without cleaning and when using the developed procedure for gas mixture cleaning. We determined maximum surface concentrations of pollutants in exhaust gases after cleaning.

Abstract: Exhaust manifolds for diesel engines are made of high-Si ferritic nodular cast irons. It is experimentally well established that their oxidation kinetics are highly sensitive to the presence of water vapor, though the mechanism for such an effect is still controversial. In the present work, isothermal oxidation tests were performed on a SiMo nodular cast iron at 700°C and 800°C in dry and humid air for 25 and 50 hours. Other samples were oxidized for 50 h with in-situ change in H₂O content after 25 h, switching from dry air to humid air or the other way round. Samples were then analyzed using XRD, SEM-EDS and Raman spectroscopy. Thermogravimetric records clearly showed the effect of temperature and environment on oxidation and decarburization. The kinetics of these phenomena depends on silica formation at the metal-oxide interface. At both temperatures, water vapor was seen to promote internal oxidation of Si instead of its external oxidation. This leads to higher oxidation kinetics at 700°C and higher decarburization kinetics at 800°C.

Abstract: This study is aimed at finding a new application of chitosan film in energy conversion material. A water vapor cell in a single chip form which consists of chitosan film on the top layer, patterned gold layer in the middle and isolator substrate in the bottom layer was manufactured and used to convert water vapor into electrical power by direct chemical interaction. When the water vapor was exposed onto chitosan film surface, the chitosan film resistance changed and as a consequence, the output voltage and current could be measured. The electrical power was significantly increased by combining several cells, namely twenty cells in series, twenty cells in parallel, twenty cells in series-parallel and twenty cells in parallel-series. It was found that twenty cells in series have the highest electrical power. Furthermore, the lifetime of a water vapor cell under water vapor exposure maintained until eight months. Therefore, chitosan film has evidenced a huge potential as energy conversion material to produce a water vapor panel in future.

Abstract: In this study, three different alloys Stainless Steel 316 (SS316), Titanium 6Al-4V (Ti6A-l4V) and Hastelloy 276 (H276) were exposed to the wet environment with 12% of water vapor and Ar-20%O₂ for 10 h at 900 °C. The oxidation behavior of the samples was analyzed using weight change measurement technique and optical microscope (OM). The phases of the oxide layer on corroded sample were determined using X-ray diffraction (XRD). The difference in the weight gain indicating the difference in the rate of the oxide growth for the samples. Sample Ti6A-l4V showed the most aggressive oxidation behavior compared to the other samples. OM analysis showed a multilayer oxide scale formed on the Ti6A-l4V and H276 samples but only single layer of oxide forms on SS316. Oxide scale for the samples were analyzed using XRD, the result showed the formation of chromia (Cr₂O₃) on SS316. Titanium oxide (TiO₂ ) and alumina oxide (Al₂O₃) were detected on Ti6Al4V, while H276 showed the formation of nickel manganese oxide (Ni_7.2Mn_0.2O₈) and nichromite (NiCr₂O₄).

Abstract: The article is focused on the physical analysis of water vapour in functional gap. The creation of condensate (respectively frost) in the cavity is not treated by norms or regulations. The level of importance of condensation is different depending on the material basis. In case of wooden window constructions, the surface treatment is degraded and their technical-physical features. The primary reason of condensation is transfer of humidity through the cavity between the window casement and its frame at reaching the temperature of dew point. The transfer causes: the difference of air pressures (which drifts vapour) – infiltration and exfiltration and diffusion of vapour (different saturation of vapour in external and internal air, diffusion flux is, under certain circumstances, able to flow in a different direction than airflow).

Abstract: The problem of outer condensation occurs considerably towards the end of summer and early autumn. Surface condensation on the outside of the glazing is rare in the corners, given the fact that the outer edges of the glazing are heated due to a thermal bridge. The coldest point on the outside of the glazing is generally in the middle with the lowest level of heat losses. Surface condensation of water vapour appears on the external surface of an insulating glazing, if the temperature at the surface of the glazing is substantially lower than the air temperature and if it drops below the dew point.

Abstract: In order to investigate the high temperature oxidation behavior of AISI 430 stainless steel in atmosphere with humidity, the thermogravimetric analysis (TGA) has been conducted for different duration under air with variable absolute humidity (from 0% to 5%) at 800 °C and 900 °C. XRD has been used to determine residual stresses in each layer and in substrate. It has been found that the oxidation kinetics and residual stresses were affected by the water vapor. After oxidation, the oxide scale composed of an inner Chromia (Cr₂O₃) layer and an outer Mn_1.5Cr_1.5O₄ spinel layer, while breakaway oxidation happened with the introduction of water vapor at 900 °C. The residual stresses in each of oxide layer are in compression and their levels varied with oxidation conditions.

Abstract: Single phase CuO films have been successfully synthesized by thermal oxidation of cupper foil in air with water vapor. The structural and optical properties of CuO films were investigated. It is observed that the grain size increases with increasing the oxidation temperature. The optical band gap of CuO film is determined by the transmittance and reflectance spectra.

Abstract: Three typical solution schemes of adjoint problems of heat transfer, phase transformations and chemical reaction at the forest fuel material surface were analyzed in this work. Characteristic times of thermal decomposition reaction suppression of forest fuel materials (needles of pine and fir-tree, leaves of birch) were presented for concerned heat transfer models. Effective heat exchange conditions which are characterized by minimal times of chemical reaction suppression in forest fuel materials and minimal extinguishing agent's expenditure were established.

Abstract: In order to obtain an ideal sample inlet membrane for ion mobility spectrometers (IMS), fumed silica was modified using hexamethyldisilazane and was incorporated into the matrix of polydimethylsiloxane (PDMS) silicone rubber to fabricate PDMS/silica mixed matrix membranes with different thickness. Dimethyl methylphosphonate (DMMP) permeability of thin silicone rubber membranes (SRM) with the least thickness of approximate 5μm was studied. DMMP concentration interior to the SRM showed the linear correlation to that external to the SRM. Thickness and temperature of SRM were two important factors influencing the permeation proportion of DMMP. Most water vapor was prevented to transfer through the SRM. In addition, the SRM had a good selectivity of DMMP/water vapor and the maximum separation factor was 4.82 when the temperature of membranes reached 80 °C.