摘要:

The paper presents the investigation of gas transfer in cylindrical channels in the presence of heterogeneous physicochemical conversions (filler evaporation in a channel, evaporation on the internal surface of a channel, catalytic reaction of the first order). With the use of the model kinetic equations for the gas molecule velocity distribution function, the solutions of the above problems have been obtained, suitable for the arbitrary ratios of free molecule path length to capillary radius, i.e. the Knudsen number. The comparison between the theoretical and experimental results on filler surface recession in a capillary during evaporation in the presence of a foreign gas is carried out. The applicability limits for the well-known phenomenological relations, used in the theory of drying, are established.

ISSN:0737-3937    

DOI:10.1080/07373938308959812

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In drying problem, particularly for drying foodstuff, modelling is very difficult. Many physical effects have to be taken into account for mass transfer ; then mass transfer coefficient varies

ISSN:0737-3937    

DOI:10.1080/07373938308959813

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The integrated solar drying system essentially consists of two selective flat plate collectors, one of them being black nickel and the other of manganese oxide deposited on galvanized iron sheet. A packed bed solar storage collector also forms a part of the system to supplement the energy required for drying after sun set. The design of the system with the calculation of the power requirement is reported in this paper. Freshly harvested high moisture paddy with an initial moisture content of 22 percent, w. b. was dried to the desirable milling percentage of 14 to 15 percent, w. b. The performance of the selective surfaces were studied to recommend the best one. Mathematical models for the temperature distribution in the pebble bed to optimize the length and depth of the storage system are given. Drying of 100 kg of paddy could be completed in 7 1/2 hours. The total and head rice yields obtained from this drying system were 70 and 65 percent respectively.

ISSN:0737-3937    

DOI:10.1080/07373938308959814

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938308959815

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Four commercially used moisture meters were compared with the official United States Department of Agriculture (USDA) air-oven method to measure the moisture content of 879 samples of corn collected from the 1979 and 1980 harvests. The moisture content of these samples ranged from 11% to 38% (wet basis). All meters were found initially to have statistically significant calibration biases ranging from 1.5% high to 3.5% low. A recalibration before the 1980 harvest reduced both the previous bias and the difference in readings among the meters. Random variations could be traced to three sources: different electrical properties of the grain samples at the same moisture content, meter precision, and oven precision. The proportion of the total variance of each was approximately 85%, 10%, and 5%, respectively. The measured total variance could be estimated as a quadratic function of moisture content, which yielded the minimum value of ± 0.8% within the range of 15.5 - 20.0% moisture content.

ISSN:0737-3937    

DOI:10.1080/07373938308959816

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938308959817

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938308959818

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938308959819

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373938308959820

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Drying and extensional behaviours of a threadline in dry spinning were investigated for polyvinylalcohol-water system. Diffusion equation, differential heat balance equation and momentum equation for extensional deformation were solved simultaneously by numerical calculation. Concentration and temperature dependencies of mutual diffusion coefficient, Trouton viscosity and vapour pressure at threadline surface, were taken into account, Rapid decrease of temperature and surface concentration of a threadline just below a spinneret cause rapid increase of the viscosity inside a threadline and limits the extensional deformationwithin a short distance.Contributions of initial viscous stress, inertia, air drag, gravity and surface tension to spinning tension were discussed. Diffusion of solvent in a threadline is controlling step of the drying rate of a threadline except the short distance below a spinneret. Changes of average concentration and temperature of a threadline in a spinning column are well correlated by a term of (distance from spinneret) / (mass velocity of polymer).

ISSN:0737-3937    

DOI:10.1080/07373938308959821

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor