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Two-phase distribution in the vertical flow line of a domestic wet central heating system  [cached]
Fsadni A.-M.,Ge Y.T.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134501030
Abstract: The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.
Wet hydrate dissolution plant
Stankovi? Mirjana S.,Kova?evi? Branimir T.,Pezo Lato L.
Hemijska Industrija , 2003, DOI: 10.2298/hemind0302061s
Abstract: The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. Main goal was increasing the detergent zeolite production capacity. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution. Wet hydrate dissolution is now fully continuous, which is important for maintaining zeolite production quality, as well as for simplifying production. The wet hydrate production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start-up, and repairs. By installing additional process equipment (centrifugal pumps and dissolving reactors) technological bottlenecks were overcome, and by adjusting NaOH tanks and dissolving reactors, the capacities of the process equipment was fully utilized.
Hydraulic Domestic Heating by Throttling  [PDF]
Mohammad A. K. Alia, Tariq Younes, Hussein Sarhan
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.26060
Abstract: In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.
Permeability of a bubble assembly: From the very dry to the wet limit  [PDF]
Florence Rouyer,Olivier Pitois,Elise Lorenceau,Nicolas Louvet
Physics , 2009, DOI: 10.1063/1.3364038
Abstract: We measure the permeability of a fluidized bed of monodispersed bubbles with soap solution characteristic of mobile and non-mobile interfaces. These experimental data extend the permeability curves previously published for foam in the dry limit. In the wet limit, these data join the permeability curves of a hard sphere suspension at porosity equal to 0.4 and 0.6 in the cases of mobile and non-mobile interfaces respectively. We show that the model of permeability proposed by Kozeny and Carman and originally validated for packed beds of spheres (with porosity around 0.4) can be successfully applied with no adjustable parameters to liquid fractions from 0.001 up to 0.85 for systems made of monodisperse and deformable entities with non-mobile interfaces.
Modeling and experimental study on limestone dissolution in wet desulphurization
湿法脱硫中石灰石溶解特性的模型及实验研究

Miao Mingfeng,
缪明烽

环境工程学报 , 2011,
Abstract: The limestone dissolution affects the slurry absorbability of SO2 and the volume of the slurry pool in the wet limestone-gypsum FGD (flue gas desulphurization). Based on theories of the mass transfer and the chemical ion balance, the model to describe the limestone dissolution is built and the experiment is carried out in this paper. Results show that modeling data are basically consistent with the experimental value and the model can perfectly describe the dissolution process. To increase the stirring intensity will obviously increase the dissolution rate in the lower pH slurry, but to increase the stirring intensity has a little influence on the rate in the higher pH slurry. The dissolution index, which is related with the Ca2+ concentration, pH and CO2 pressure in gas phase, and dissolution coefficient which is related with temperature, are defined in this paper. The condition of limestone dissolution is that the dissolution index must be less than dissolution coefficient.
DISSOLUTION OF THE SECOND PHASE DURING CONTINUOUS HEATING PROCESS
匀速加热过程中第二相的扩散溶解

WANG Xiaoying,ZHANG Ruijie,JIE Wanqi,
王晓颖
,张瑞杰 介万奇

金属学报 , 2004,
Abstract: A dissolution model of the plate-like and spherical second phases in the multiphase alloy during continuous heating process with constant rate has been proposed. The effects of heating rate and interface curvature on the concentration profiles in the matrix and the dissolution rate of the second phase were discussed. The model was applied to calculate the dissolved fraction of the second phase before melting during heating process. The calculated results for Al-5.8%Cu alloys, where the eutectic melting fraction of the non-equilibrium eutectic was determined by DSC analysis, agree well with the experimental ones, clearly indicating the validity of the developed model.
Thermochemical Assessment of Solid and Liquid Fuels Used for Domestic Space Heating in Jordan  [PDF]
Khalid M. Tawarah
Green and Sustainable Chemistry (GSC) , 2014, DOI: 10.4236/gsc.2014.44026
Abstract: The gross calorific values of crude and exhausted olive pomace, oak, almond, olive wood, olive oil, kerosene, and diesel are reported in this article. Conversion of crude olive pomace into exhausted olive pomace resulted in 10% reduction in calorific value. The net calorific value of crude olive pomace amounts to 92% of its gross calorific value. The ultimate and proximate analyses of crude olive pomace representing the 2006-2008 olive harvest seasons were determined and compared with analyses pertaining to the 2009-2011 olive harvest seasons in Jordan. Controlled charring of crude olive pomace reduced its mass down to about 20%. Pyrolysis thermogravimetric (TG) and differential thermogravimetric (DTG) curves were recorded under nitrogen atmosphere for crude olive pomace and wood samples. Quantitative data on three DTG major peaks are reported for wood samples and crude olive pomace. A comparison based on market price and calorific value of a fuel showed that olive pomace is the most rewarding fuel for domestic space heating in Jordan.
典型MoSi2发热元件物相与显微结构分析
The Comparative Analysis of Micor-topography for Kanthal and Domestic MoSi2 Heating Element
 [PDF]

黄文江,周颖,李斯,马成良,史幸福,王世界
- , 2017,
Abstract: 采用XRD、SEM和EDS等手段分别对Kanthal公司Super1700、Super1800和国产某厂三种不同MoSi2发热元件的物相组成、微观形貌和微区元素成分进行分析,探讨了非MoSi2相对典型发热元件使用性能的影响,结果表明:(1)单质Mo对MoSi2发热元件使用温度的提高非常不利;在高温条件,参与的单质Mo会与氧气反应生成气相的MoO3,使发热元件表面鼓包并造成玻璃膜破坏。(2)国产发热元件生产过程中应适当提高膨润土的加入量,并严格控制膨润土中K、Na等活性碱金属氧化物的量。(3)通过添加W元素合金化的方法来制备复合MoSi2粉并取代传统的MoSi2粉,可以提高发热元件的使用温度和使用寿命。
The phase composition, microstructure and micro-area elements analysis of Kanthal and domestic MoSi2 heating element were studied by X-ray diffraction analysis(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS). The impacr of other substancesexcept for the MoSi2 phase on the performance of typical MoSi2 heating elements was investigated. The results showed that:(1)Elemental Mo was detrimental to improving the service temperature of the MoSi2 heating element. MoO3 gas was formed by the reaction of residual Mo and oxygen at high temperture, resulting in the emergence of bubble on the surface and damage to the glass film. (2)It was necessary to increase the amount of bentonite during the production process of domestic heating element, while the amount of K, Na and other active alkali metal oxide in the bentonite was strictly controlled.(3)The MoSi2 composite powders were synthesized via alloying method of adding W in replace of traditional MoSi2 powders, which could improve the service life and operating temperature of the heating element.
Catalytic Wet Air Oxidation of Oxalic Acid using Platinum Catalysts in Bubble Column Reactor: A Review  [PDF]
S. Roy,M. Vashishtha,A. K. Saroha
Journal of Engineering Science and Technology Review , 2010,
Abstract: Wastewater treatment and re-use of industrial process water are critical issue for the development of human activities andenvironment conservation. Catalytic wet air oxidation (CWAO) is an attractive and useful technique for treatment of effluentswhere the concentrations of organic pollutants are too low, for the incineration and other pollution control techniquesto be economically feasible and when biological treatments are ineffective, e.g. in the case of toxic effluents. In CWAO,combustion takes place on a Pt/Al2O3 catalysts usually at temperatures several degrees below those required forthermal incineration. In CWAO process, the organic contaminants dissolved in water are either partially degraded by meansof an oxidizing agent into biodegradable intermediates or mineralized into innocuous inorganic compounds such as CO2,H2O and inorganic salts, which remain in the aqueous phase. In contrast to other thermal processes CWAO produces no NOx,SO2, HCl, dioxins, furans, fly ash, etc. This review paper presents the application of platinum catalysts in bubble columnreactor for CWAO of oxalic acid.
Decreases in Mercury Wet Deposition over the United States during 2004–2010: Roles of Domestic and Global Background Emission Reductions  [PDF]
Yanxu Zhang,Lyatt Jaeglé
Atmosphere , 2013, DOI: 10.3390/atmos4020113
Abstract: Wet deposition of mercury (Hg) across the United States is influenced by changes in atmospheric conditions, domestic emissions and global background emissions. We examine trends in Hg precipitation concentrations at 47 Mercury Deposition Network (MDN) sites during 2004–2010 by using the GEOS-Chem nested-grid Hg simulation. We run the model with constant anthropogenic emissions and subtract the model results from the observations. This helps to remove the variability in observed Hg concentrations caused by meteorological factors, including precipitation. We find significant decreasing trends in Hg concentrations in precipitation at MDN sites in the Northeast (?4.1?±?0.49%?yr ?1) and Midwest (?2.7?±?0.68%?y r?1). Over the Southeast (?0.53 ±?0.59%?yr ?1), trends are weaker and not significant, while over the West, trends are highly variable. We conduct model simulations assuming a 45% decrease in Hg emissions from domestic sources in the modeled period and a uniform 12% decrease in background atmospheric Hg concentrations. The combination of domestic emission reductions and decreasing background concentrations explains the observed trends over the Northeast and Midwest, with domestic emission reductions accounting for 58–46% of the decreasing trends. Over the Southeast, we overestimate the observed decreasing trend, indicating potential issues with our assumption of uniformly decreasing background Hg concentrations.
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