摘要:

AbstractThe temperature profile, total emissivity, flux density distribution, and effective mean penetration distance were determined from measurements in high‐temperature solar fluidized beds. A theoretical model is proposed to describe the complex heat transfer phenomena in the radiation penetration zone of the fluidized layers. The results correlated well at incipient fluidizing conditions for beds of silicon carbide and chamotte but were found imprecise for beds of zirconia and silica san

ISSN:0001-1541    

DOI:10.1002/aic.690280402

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractA recent publication of Fractionation Research Inc. (FRI) (Sakata and Yanagi, 1979) provides experimental evidence that tray efficiency initially rises with increasing pressure, reaches a maximum value, and then decreases again at very high pressures. It is shown in this paper that at these high pressures, significant amounts of vapor can be entrained with the downflowing liquid, e.g., abt. 50 mol per 100 mol liquid at 2,760 kPa. A new model is developed to determine the effect of vapor entrainment on tray efficiency. It is shown that the experimentally observed loss of tray efficiency corresponds with the entrainment rates found at high pressures.

ISSN:0001-1541    

DOI:10.1002/aic.690280403

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractIntraparticle forced convection was considered in order to explain experimentally observed changes in effective diffusivity (apparent) with flowrate, when measures are carried out in fixed beds.A complete model taking into account intraparticle diffusion and forced convection together with film diffusion is derived in order to analyze diffusivity measurements by physical methods, both in perfectly mixed reactors and fixed beds.The experiments were carried out with hydrogen tracer in a partial oxydation catalyst.Implications of the use of such “apparent” effective diffusivities in reactor design are discussed, showing that errors of 100% can be m

ISSN:0001-1541    

DOI:10.1002/aic.690280404

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractAqueous solutions of drag‐reducing polymers were injected into turbulent water flow in a pipe. The injection point was situated where the flow was well‐developed. Thus, subsequent steamwise variations in pressure drop were due to the injected polymer spreading out across the pipe. The axial development of local drag reduction was monitored by a series of closely‐spaced pressure tappings. The corresponding radial dispersion of the injected polymer, as it travelled downstream, was assessed by sampling the flow at various points.Local drag reduction, due to either point injection at the centerline or injection through a slot in the wall, was found to increase with distance downstream. This increase was related to the streamline increase of polymer concentration in a narrow annulus near the pipe wall. It was tentatively concluded that the effective annulus was bounded by 15 ≤y+ ≤ 100, in agreement with previous deductions from less direct

ISSN:0001-1541    

DOI:10.1002/aic.690280405

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractAqueous solutions of polythyleneoxide (Polyox WSR‐301) were injected into a pipe flow through either a small tube at the center line or an annular slot in the wall. The solution contained polymer at an injection concentration of 1,000 wppm. Injection into water flow with a Reynolds number Re = 3.5 × 104was at a rate which gave a mean polymer concentration of 5.0 wppm in the water flow. A laser‐Doppler anemometer (LDA) was used to measure the streamwise turbulent velocity at various radial positions and at several stations downstream from the injection point.Results were obtained for mean velocity and intensity profiles; autocorrelations; and one‐dimensional energy spectra. The mean bursting period was determined using the “short‐sampling‐time” autocorrelation method. Changes in all these quantities due to polymer injection were found to depend on the amount of local drag reduction at that particular downstream station but were independent of the local polymer concentration at the m

ISSN:0001-1541    

DOI:10.1002/aic.690280406

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractThe problem of multicomponent liquid phase adsorption in fixed beds was studied further. In contrast to the earlier work (Hsieh et al., 1977), the method developed in this work is more efficient and also has a greater scope of applicability as it incorporates the use of the IAS (Ideal Adsorbed Solution Theory) method for the estimation of multicomponent adsorption equilibrium data. It was shown that the use of the more complex IAS method for the prediction of the isotherm data does not present insurmountable obstacles as once feared (DiGiano, 1978) but provides much better prediction of carbon adsorption. An extension of the method to batch adsorption was shown to be straightforward and presented no special difficulty.

ISSN:0001-1541    

DOI:10.1002/aic.690280407

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractConcentrations of NO, NH3, and HCN, together with coal particle burnout and gas composition, were measured during combustion of a bituminous coal. Control of incoming secondary gas swirl level and overall stoichiometric ratio led to significant reductions in nitrogen oxide pollutant concentration. In‐situ measurements showed that coal particles were confined near the reactor center during rapid particle reaction. This took place in a locally fuel‐rich environment, producing near‐quantitative conversion of fuel‐nitrogen to NH3and HCN, with some NO. Subsequent gas phase reactions of these nitrogen species were identified as important in establishing the ultimate NO concen

ISSN:0001-1541    

DOI:10.1002/aic.690280408

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractA new procedure for the estimation of parameters in two‐component vapor‐liquid equilibrium is presented. It allows for measurement errors in all variables and gives better fits than most other procedures because of the use of two relations between the variables rather than one as is commonly used. An approximate and an exact solution are described and the importance of using all thermodynamic and statistical information is illustrated for the Wilson and UNIQUAC models. New alternatives for analysis of residuals are also discus

ISSN:0001-1541    

DOI:10.1002/aic.690280409

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractAn electrolyte local composition model is developed for excess Gibbs energy, which is assumed to be the sum of two contributions, one resulting from long range electrostatic forces between ions and the other from short range forces between all the species. The validity of the model is demonstrated for systems emcompassing the entire range from molecular liquid to fused salt.

ISSN:0001-1541    

DOI:10.1002/aic.690280410

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY

摘要:

AbstractHigh‐quality (95%) steam‐water critical flow through a straight pipe was studied using high‐speed photographic and holographic techniques. The results indicate that most of the water exists as a discontinuous or continuous thin film which flows along the wall with a speed much slower than that of the steam. This results in slip ratios higher than those reported before. Although a separated flow model would seem to describe the actual flow situation more closely than other models, the assumption of thermal equilibrium between phases and the fact that the flow is not separated except close to the exit plane are probably explanations for differences in slip ratios obtained in this study from those pred

ISSN:0001-1541    

DOI:10.1002/aic.690280411

出版商:American Institute of Chemical Engineers    

年代:1982

数据来源: WILEY