00662 A computational model of a domestic solar heating system with underground spherical thermal storage

00662 A computational model of a domestic solar heating system with underground spherical thermal storage

13 In situ investigations of sintering and crystalliza98100650 tion of lithium aluminosilicate glass ceramics Zimmer, J. et al. Glass Sci. Technol., 1...

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13 In situ investigations of sintering and crystalliza98100650 tion of lithium aluminosilicate glass ceramics Zimmer, J. et al. Glass Sci. Technol., 1997, 70, (6), 186-188. The paper investigates the sintering and crystallization behaviour of a LizO-AlsOs-Si02 glass powder containing TiOz and ZrOz. In-situ measuring methods of high-temperature dilatometry, high-temperature X-ray diffractometry and DTA at heating rates between 0.5 and 20 K/mm were conducted. By comparing the results of the different methods the shrinkage could be explained as an overlap of sintering and crystallization processes. As the heating rate increases, the sintering and crystallization processes are more sharply separated, so that higher final densities of the sintered samples are possible.

Manufacture of glass-ceramic tiles from fly ash. 98100651 Hnat, J. G. et al. PCT Int. Appl. WO 97 37,949 (Cl. CO3ClO/OO), 16 Ott 1997, US Appl. 629,558, 9 Apr 1996, 33 pp. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized in this process under conditions effective for combustion of the organic material and partial oxidization of the metallic contaminants and the glass forming materials. The oxidized glass-forming materials are vitrified to form a glass melt, and the glass melt is then formed into tiles containing metallic contaminants to produce ceramic tiles. Molded nitrogen oxide decomposing ceramics and 98100652 their manufacture Aido, Y. Jpn. Kokai Tokkyo Koho JP 09,248,466 [97,248,466] (Cl. BOlJ351 02), 22 Sep 1997, Appl. 96/57,508, 14 Mar 1996, 8 pp. (In Japanese) The oxidative decomposition of NO, is possible using ceramics with a sintered moulded body of a mixture of coal ash and an AI(HzP04)a based inorganic binder and photo-oxidation catalytic metal oxide applied and fixed on the front and/or back sides of the body. The ceramics are prepared by applying a coating mixture containing the metal oxide and organic or inorganic vehicle on the moulded coal ash-binder mixture before or after sintering. Another application for the ceramics are sound barrier panels for high ways. Processing and characterization of anthracite98100653 based refractory paste Goncalves, M. M. F. er al. Cerum. Ind., 1997, 2, (l/2), 36-40. (In Portuguese) The development of a modified refractory paste consisting of a mixture of calcined anthracite, pitch, and solvents is presented. The paste displays compression resistance and flexure resistance three times greater than the original and an increased total fracture energy. The composition included a binder matrix of pitch with a high level of resin 4, packed aggregate of electrically calcined anthracite with a low level of friable particles, and an optimum level of binder. The electrical resistivity was reduced and the characteristics of application and volumetric variation in firing were kept at adequate levels. Purification of hot dust- and tar-containing waste 98100654 gases Boehm, E. et al. Ger. Offen. DE 19,611,119 (Cl. BOlDSOiOO), 25 Sep 1997, Appl. 19,611,119, 21 Mar 1996, 4 pp. (In German) Waste gases containing hot gas and tar from CaCz manufacture in an arc furnace are passed through ceramic candle filters at 200-900°C to remove dust and then passed through a scrubber or electrostatic filter at 50-200°C for tar removal. The dust content is decreased to ~10 mg/kg waste gas, and the gas is practically tar-free. The candle filters are periodically cleaned by using pressure shocks and/or back-washing. Residual quartz (RQ) content in silica products 98100655 used in the coking industry Witos, J. Karbo-Energochemical-Ekol., 1996, 41, (2), 59-61. (In Polish) The role of residual quartz content in the evaluation of the quality of silica refractories used in the coking industry is reviewed. 98100656 Slagging effects of carbon fly ashes on magnesitechrome refractories Croquevielle, E. A. Key Eng. Mater., 1997, 132-136, (3) 1669-1672. Chemical bond and direct bond magnesite-chromite refractories subjected to slagging and wear process in the arch of a reverberatory furnace and in laboratory studies were studied. The chemical, physical, and mechanical properties of the refractories and fly ashes were tested. From the Cu melting industry used refractories and refractories artificially corroded with carbon fly ashes in laboratory at 1450°C were investigated by hot-stage microscopy, SEM, and electron microprobe analyser. Fly ashes with a high Si02 and Fe content penetrated inside the refractory structure and formed low-melting compounds, especially in a reducing atmosphere, due to the Fe sensibility to the oxygen partial pressure. The atmosphere of the thermal unit, the quantity and chemical composition of the ashes generated during combustion, and the chemical and mineralogical composition of the refractory all determined slagging process.

Space heating and cooling

98lOO657 Study on structure of zirconia ceramic membrane Wu, J. et al. Wuji Cailiao Xuebao, 1996, 11, (4) 719-722. (In Chinese) Derived by a sol-gel process, using zirconyl chloride as starting material, non-supported zirconia ceramic membranes were characterized by DTATG, XRD, BET, and SEM. The results showed that the membranes were highly oriented. The tetragenal zirconia was precipitated at low temperature then transformed into the monoclinic phase which was thermodynamically stable at high temperature. The pores with a diameter of less than 50 nm took on the double value distribution. Experimental analysis corroborated the structure model of the ceramic membranes. 98100658 Use of coal fly ash for ceramics: a case study for a large Spanish power station Queralt, 1. et al. Fuel, 1997, 76, (8) 787-791. Binary mixtures of fly ash from the Teruel power station (NE Spain) and plastic clays from the Teruel coal mining district were used to manufacture ceramic products with up to 50 wt% of mullite and 16 wt% of feldspars. The firing behaviour of fly ash and the ceramic mixtures were investigated by determining their changes in mineralogy and basic ceramic properties such as colour, bulk density, water absorption and firing shrinkage. To determine the changes on heating suffered by both the fly ash and the ceramic bodies, firing tests were carried out at temperatures between 900 and 1200°C in short firing cycles. The resulting ceramic bodies exhibit features that suggest possibilities for use in paving stoneware manufacture, tiling and conventional brickmaking. 98lOO659 Waste heat utilization in a ceramic industry Akter, S. and Hossain, I. Inc. J. Energy Res., 1997, 21, (13) 1215-1221. Investigates the scope for energy conservation in a ceramic factory. It was found that the sensible heat of the flue gas from kilns could be used to heat the casting shop. A pebble bed waste heat regenerator was chosen to collect the sensible heat of the flue gas. Experiments were performed on a pilot plant scale pebble bed to study its characteristics using a flue gas stream whose temperature and composition were similar to the factory conditions. The results of the heating cycle showed that 14500 kcal hh’ of heat can be collected from flue gas in a 0.126 m3 bed. This information was used to design a complete retrofit system. Financial analysis of the proposed project showed that it has a pay-back period of I5 months.

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98100660 Air drying in an adsorption column for cooling operations in open-cycle adsorption systems Stegou-Sagia A. and Damanakis, M. Applied Energy, 1997, 56, (I), 9-26. The paper presents a computer algorithm which has been developed concerning the heat-and-mass transfers during the process of air drying in an adsorption column with silica-gel. It is well known that such a column is the major component in open-cycle adsorption systems used, in countries with high solar radiations, for cooling operations. The method proposed is based on an appropriate solution of the system of differential equations describing the operation of the physical model. The model accounts for an adsorption column with adiabatic mass-transfer and climatic data for Athens, Greece. Results for the temperature, humidity, enthalpy of air and silica-gel within the column are given for a wide range of parameters, such as the distance from the air entrance section in the column, the hour, the day, the season, the place, etc. 98100661 Analysis of a latent heat cold storage unit Ismail, K. A. R. and Gonqalves, M. M. Int. .I. Energy Res., 1997, 21, (13) 1223-1239. A conduction based model is presented for solving the phase change heat transfer problem around a vertical cylinder submersed in the phase change medium. The energy equation is coupled to the flow problem by an energy balance. The system of equations is solved numerically by using the average control volume technique and the AD1 approach. The results show the effects of the variation of the Biot number, Stefan number, the inlet fluid temperature and the ratio of the outer to the inner tube radius on the solidified mass fraction, NTU, effectiveness and the time for complete solidification. 98100662 A computational model of a domestic solar heating system with underground spherical thermal storage Inalli, M. er al. Energy, 1997, 22, (12), 1163-1172. This theoretical study deals with a domestic heating system assisted by solar energy stored in an underground spherical container. The system includes a heat pump. The analytical model employed calculates the water temperature in the storage vessel, as well as the temperature distribution in the surrounding geological structure, by using the monthly-average solar radiation and ambient temperature. Storage temperature, collector efficiency, performance coefficient of the heat pump (COP) and annual solar fraction are computed and presented in various graphs. The importance of seasonal solar energy storing in the ground is demonstrated.

Fuel and Energy Abstracts

January 1998

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