摘要:

Non-linear dynamic models of corn drying and wet-milling quality degradation are obtaineddirectly from experimental data. No assumptions about the underlying mechanisms are made. Relative advantages of recurrent versus explicit-time models and technical issues are discussed. This type of model is well suited for very fast on-line simulations, for example in a predictive optimal control algorithm.

ISSN:0737-3937    

DOI:10.1080/07373939708917280

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The drying characteristics of a single oil palm kernel suspended in a drying tunnel is studied. Luikov's unsteady state simultaneous heat and mass transpon equations are proposed as the governing equations. The model is simulated using the explicit and modified implicit Crank Nicholson finite difference algorithms. The desorption isotherms of the kernel warj determined using an environmental chamber and the data generated was found to fit the Hasley's and Henderson's equations well. The mass diffusion coefficient was determined by using a distributed system parameter identification technique where a weighted least square criterion between model and experimental average moisture content and temperature profiles is optimized using the Lagrangian algorithm within the constraints of the governing equations. The simulated parameter estimated drying characteristics were found to be in good agreement with experimental values.

ISSN:0737-3937    

DOI:10.1080/07373939708917281

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Moisture sorption characteristics of whole pistachio nuts were investigated at 10, 20, and 30°C using the static method. The sorption isotherms exhibited hysteresis over the range of 0.10-0.80 water activity which was succesfully interpreted using BET, GAB, Oswin, Smith, Henderson, Chung-Pfost and Halsey mathematical models and from which the BET, GAB and Oswin models were found to give the best fit. Monolayer moisture content of pistachio nuts was determined from BET and GAB equations and the isosteric heat of sorption data were derived using Clausius-Clapeyron equation and presented in graphical form. The information generated can be utilized to optimize the packaging parameters for long term storage of pistachio nuts.

ISSN:0737-3937    

DOI:10.1080/07373939708917282

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The purpose of this study is to examine the influence of drying conditions on paddy mechanical behavior, evaluated by the evolution of the percentage of broken kernels during drying. Results show that air temperature alone cannot explain the observed quality degradation of rice during drying. The drying rate and the drying time are mainly influenced by the air temperature, and to a lesser extent, by the evaporating capacity of air at low temperatures. The percentage of broken kernels increases very rapidly with the evaporating capacity of drying air.

ISSN:0737-3937    

DOI:10.1080/07373939708917283

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An analysis of desarption isotherms for potato shows the following probable qualities in the water-potato sysarn. in the natural staa the walcr is bound rather strongly due to loss of rotational degrees of freedom in the sorbed molecules, which is caused by small molecular voids in the cellulose structure. This strucmre therefore is formcd as a uniformly cross bound state of the OH-groups. This slate prevails up to a cenin temperature, above which a reaction sas in. whcre OH bonds are successively braken, giving passibility for a panial rotation of sorbed molecules. in the range of lower moisture conlcnt the cellulose strucmre is changed into n crystalline slate a in wood, although the dcgrcc of crystallinity is lower, which is thc

ISSN:0737-3937    

DOI:10.1080/07373939708917284

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The moisture adsorption and desorpcion characteristics of blanched and osmotically treated apples and papayas and the color of the equilibraced samples were evaluated at 25-C. The sorption isotherms were in agreement with the reported shape for high sugar foodstuffs. A two-way analysis of variance showed that there was not hysteresis for the blanched fruits; however, this phenomenon was present in the osmotically treated samples. Different equations proposed in the literature were used to fit sorption data. The best fit was obtained with GAB model (average mean relative deviation of 9.8%). The apples' white and the papayas' yellow indexes of the equilibrated fruits decreased as a, increased. Browning of the apples varied with the type of isotherm (adsorption or desorption) and with the initial sugar content.

ISSN:0737-3937    

DOI:10.1080/07373939708917285

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In tropical countries, sun drying is still the most popular method used for processing root and tuber crops like cassava and yam. Relatively very little has been done on studying the kinetics of sun drying a bed of chips of cassava and similar crops, but this information is invaluable in finding options for reducing drying time and costs, and increasing tonnage produced. This project studied some factors that have an effect on the sun drying rate of cassava chips. The factors were ambient temperature, relative humidity, radiation intensity, air velocity, and loading density.

ISSN:0737-3937    

DOI:10.1080/07373939708917286

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The main concept oithis research is to develop a flexible modular dryer that combines two different sources of non-conventional energy. In this study, solar energy and producer gas generated by an up-flow charcoal gasifier were considered.

ISSN:0737-3937    

DOI:10.1080/07373939708917287

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An existing drying simulation model for softwood heartwood is revised lrom a theoretical point of view and is completed by extracting all the essential material parameters from moisture and temperature profiles measured in direct drying experiments. Some additional experimental results are presented to validate the qualitative characteristics of the model. The resulting computational model shows good agreement with experiments in the drying temperature range 45-120°C. Special attention is paid to the evolution of moisture gradient during drying, as the next step of the simulation project will be using the result as an input data for a computational stress model.

ISSN:0737-3937    

DOI:10.1080/07373939708917288

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Solar dryers have been considered for timber drying in a number of countries because of the expected savings in drying costs. From a review of past works on solar, natural, and conventional drying it was observed that while solar dryers were able to dry timber faster compared to natural drying, the difference was only marginal in some instances. The drying rates are expected to be dependent upon ambient conditions in which the dryera are operated. Solar dryers would operate more efficiently in countries with low humidity than in tropical regions. Thus the thermal performance and also the economics of solar dryer is country dependent. In the present paper, a comparison of the drying rates obtained with a solar dryer is made with that obtained with an electrically operated drying kiln.

ISSN:0737-3937    

DOI:10.1080/07373939708917289

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor