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Melting characteristics along a bundle of horizontal heated cylinders immersed in a liquid ice layer
96 ANNUAL LITERATURE SURVEY 1996 flow processes. Irreversibilities in these processes are related to temperature and mole-fraction deviations from equilibrium which result from internal-exchange delays. The method is applied to a heat-rejecting, two-phase, counter flow of an NH3/H2 O binary mixture with liquid matter in excess. A parametric study with different values of the three delay ratios involved has been performed and yields, among others, entropy production, temperature deviations, and heat exchange with the ambient. (Authors)
Fluidized-bed combustion for energy production from olive cake Abu-Qudais M., Energy (Oxford), 1996, 21/3 (173-178). In English. An experimental combustion study is presented of olive-oil mill waste (olive cake, OC) in a fluidized bed combustor. Tests were performed in a 13.2-cm i.d. reactor. Cold-flow tests included investigations of the effects of particle-size distribution, fluidization velocity, and bed height. Combustion was carried out by feeding the OC in a bed of sand particles. The temperature distribution was found to become fairly uniform 12 cm above the distributor plate. The combustion intensity was about 812 kg/m ~ -h and increased with bed height between 0. l and 0.15 m. The combustion efficiency ranged from 86 to 95 % and increased with air-flow rate. (Author) Development of two biomass control strategies for extended, stable operation of highly efficient biofilters with high toluene ioadings Smith F.L., Sorial G.A., Suidan M.T., Breen A.W., Biswas P. & Brenner R.C., Environmental Science & Technology, 1996, 30/5 (1744-1751). In English. For stable long-term continuous operation of highly loaded trickle bed air biofilters, the prevention of plugging due to accumulating biomass is essential for avoiding biofilter failure. Two biomass control strategies were evaluated to maintain high VOC removal efficiencies at high toluene loadings over 200 days. A sustained toluene removal efficiency of over 99°/. was achieved. Backwashing with medium fluidization was found to be very effective in preventing accumulation of excess biomass. The use of nitrate (NO3 -b0 instead of ammonia (NH3 -N) as the sole source of nutrient-nitrogen (N) was very effective in reducing the observed biomass yield. (from Authors) Decomposition of hydroxybenzoic and humie acids in water by ultrasonic irradiation Nagata Y., Hirai K., Bandow H. & Maeda Y., Environmental Science & Technology, 1996, 30/4 (1133-1138). In English. Sonochemical decomposition of a series of hydroxy-benzoic acids such as monohydroxy-, 3,4-dihydroxy-, 3,4,5-trihydroxybenzoic acids, tannic acid, and reagent and prepared humic acids in water under argon or air atmosphere was investigated. It is suggested that, in sonolysis under argon, the main sonochemical decomposition of the substances employed in this study proceeds via reactions with OH radicals in the bulk solution and that the contribution of thermal decomposition in cavitation bubbles or the interfacial region (between the bubbles and bulk solution) is small. In the sonolysis under air atmosphere, the role of oxygen was small in monohydroxybenzoic acids but increased with increasing numbers of OH groups substituted on the aromatic ring, suggesting the occurrence of decomposition of polyhydroxybenzoic acids induced by oxygen molecules at the interface. The chloroform formation potentials of 3-hydroxybenzoic acid and humic acids decreased due to the sonication, but the reduction in the potential was less than the corresponding amounts of decomposition of the starting substances. (from Authors) Melting characteristics along a bundle of horizontal heated cylinders immersed in a liquid ice layer Yamada M., Fukusako S., Morizane H., Myoung-Hwan Kim & Schneider W., Experimental Thermal & Fluid Science, 1996, 12/3 (305-312). In English. Experiments were performed to investigate the melting of liquid ice along a bundle of horizontal heated cylinders. A mixture of fine ice particles and ethylene glycol aqueous solution was adopted as the liquid ice for the test. In one set of experiments, the liquid ice was a quiescent layer, whereas in a second set of experiments the liquid ice was a fluidized bed layer. Measurements were carried out for a range of initial concentration of aqueous binary solution, heat flux, and airflow rate for fluidization. The heat transfer coefficient for the fluidized liquid ice bed was more than 25 times as large as that for the quiescent liquid ice bed. (from Authors)
Interactions of particles and mierobubbles with turbulence Maxey M.R., Chang E.J. & Wang L.-P., Experimental Thermal & Fluid Science, 1996, 12/4 (417-425). In English. Dilute, dispersed two-phase flows arise in many contexts ranging from solid particles or droplets in gas flows to bubbles in liquids. Many of the flows of interest are turbulent, which presents a complex problem to analyze or to determine the dominant physical processes contributing to the observed phenomena. Advances in experimental techniques have made it possible to measure directly turbulent and particle velocity fluctuations in dilute systems. This has provided a counterpart to advances in computational and analytical models and a basis on which to test these models. Three specific areas are considered: the fluctuating forces on an individual particle in an unsteady flow, the response of a solid particle to a turbulent air flow, and the corresponding response of a small bubble in turbulent liquid flows. (from Authors) Free jet expansion and gas entrainment characteristics of a plunging liquid jet Evans G.M., Jameson G.J. & Rielly C.D., Experimental Thermal & Fluid Science, 1996, 12/2 (142-149). In English. The change in effective jet diameter is measured as a function of free jet length for vertical liquid jets passing through air. The data are incorporated into a model to predict the rate of gas entrainment for a liquid jet plunging into a confined column of liquid. In the model it was assumed that the total gas entrainment rate included gas contained within the effective diameter of the free jet at the plunge point and an annular film adjacent to the surface of the jet, where the outer boundary of the film was defined to be the separating stream-
Fluidized-bed combustion for energy production from olive cake Abu-Qudais M., Energy (Oxford), 1996, 21/3 (173-178). In English. An experimental combustion study is presented of olive-oil mill waste (olive cake, OC) in a fluidized bed combustor. Tests were performed in a 13.2-cm i.d. reactor. Cold-flow tests included investigations of the effects of particle-size distribution, fluidization velocity, and bed height. Combustion was carried out by feeding the OC in a bed of sand particles. The temperature distribution was found to become fairly uniform 12 cm above the distributor plate. The combustion intensity was about 812 kg/m ~ -h and increased with bed height between 0. l and 0.15 m. The combustion efficiency ranged from 86 to 95 % and increased with air-flow rate. (Author) Development of two biomass control strategies for extended, stable operation of highly efficient biofilters with high toluene ioadings Smith F.L., Sorial G.A., Suidan M.T., Breen A.W., Biswas P. & Brenner R.C., Environmental Science & Technology, 1996, 30/5 (1744-1751). In English. For stable long-term continuous operation of highly loaded trickle bed air biofilters, the prevention of plugging due to accumulating biomass is essential for avoiding biofilter failure. Two biomass control strategies were evaluated to maintain high VOC removal efficiencies at high toluene loadings over 200 days. A sustained toluene removal efficiency of over 99°/. was achieved. Backwashing with medium fluidization was found to be very effective in preventing accumulation of excess biomass. The use of nitrate (NO3 -b0 instead of ammonia (NH3 -N) as the sole source of nutrient-nitrogen (N) was very effective in reducing the observed biomass yield. (from Authors) Decomposition of hydroxybenzoic and humie acids in water by ultrasonic irradiation Nagata Y., Hirai K., Bandow H. & Maeda Y., Environmental Science & Technology, 1996, 30/4 (1133-1138). In English. Sonochemical decomposition of a series of hydroxy-benzoic acids such as monohydroxy-, 3,4-dihydroxy-, 3,4,5-trihydroxybenzoic acids, tannic acid, and reagent and prepared humic acids in water under argon or air atmosphere was investigated. It is suggested that, in sonolysis under argon, the main sonochemical decomposition of the substances employed in this study proceeds via reactions with OH radicals in the bulk solution and that the contribution of thermal decomposition in cavitation bubbles or the interfacial region (between the bubbles and bulk solution) is small. In the sonolysis under air atmosphere, the role of oxygen was small in monohydroxybenzoic acids but increased with increasing numbers of OH groups substituted on the aromatic ring, suggesting the occurrence of decomposition of polyhydroxybenzoic acids induced by oxygen molecules at the interface. The chloroform formation potentials of 3-hydroxybenzoic acid and humic acids decreased due to the sonication, but the reduction in the potential was less than the corresponding amounts of decomposition of the starting substances. (from Authors) Melting characteristics along a bundle of horizontal heated cylinders immersed in a liquid ice layer Yamada M., Fukusako S., Morizane H., Myoung-Hwan Kim & Schneider W., Experimental Thermal & Fluid Science, 1996, 12/3 (305-312). In English. Experiments were performed to investigate the melting of liquid ice along a bundle of horizontal heated cylinders. A mixture of fine ice particles and ethylene glycol aqueous solution was adopted as the liquid ice for the test. In one set of experiments, the liquid ice was a quiescent layer, whereas in a second set of experiments the liquid ice was a fluidized bed layer. Measurements were carried out for a range of initial concentration of aqueous binary solution, heat flux, and airflow rate for fluidization. The heat transfer coefficient for the fluidized liquid ice bed was more than 25 times as large as that for the quiescent liquid ice bed. (from Authors)
Interactions of particles and mierobubbles with turbulence Maxey M.R., Chang E.J. & Wang L.-P., Experimental Thermal & Fluid Science, 1996, 12/4 (417-425). In English. Dilute, dispersed two-phase flows arise in many contexts ranging from solid particles or droplets in gas flows to bubbles in liquids. Many of the flows of interest are turbulent, which presents a complex problem to analyze or to determine the dominant physical processes contributing to the observed phenomena. Advances in experimental techniques have made it possible to measure directly turbulent and particle velocity fluctuations in dilute systems. This has provided a counterpart to advances in computational and analytical models and a basis on which to test these models. Three specific areas are considered: the fluctuating forces on an individual particle in an unsteady flow, the response of a solid particle to a turbulent air flow, and the corresponding response of a small bubble in turbulent liquid flows. (from Authors) Free jet expansion and gas entrainment characteristics of a plunging liquid jet Evans G.M., Jameson G.J. & Rielly C.D., Experimental Thermal & Fluid Science, 1996, 12/2 (142-149). In English. The change in effective jet diameter is measured as a function of free jet length for vertical liquid jets passing through air. The data are incorporated into a model to predict the rate of gas entrainment for a liquid jet plunging into a confined column of liquid. In the model it was assumed that the total gas entrainment rate included gas contained within the effective diameter of the free jet at the plunge point and an annular film adjacent to the surface of the jet, where the outer boundary of the film was defined to be the separating stream-