摘要:

Drying studies were carried out on single droplets suspended from a rotating nozzle in a horizontal wind tunnel. Droplets were of solution of a third type of skin-forming material, namely the natural products skim milk or fructose. Droplet weight and temperature were measured during the drying process. Dried crusts were recovered and examined by Scanning Electron Microscopy.

ISSN:0737-3937    

DOI:10.1080/07373939308916927

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A mathematical model is developed to predict the performance of single-stage and multi-stage drying systems using spouted beds. The model uses unsteady state analysis for batch operation to simulate the steady state operation of a continuously fed spouted bed. A parametric study is carried out to study the effect of the following parameters on the performance of a single-stage grain drying system: air flow rate per unit mass of the grain in the bed, ambient air temperature and humidity, initial and target moisture contents, the residence time in the bed, and the effectiveness of the heat exchanger to recover the thermal energy in the exhaust air. The parametric study is also extended to investigate the effect of these parameters (except ambient air temperature and humidity) on the performance of the multi-stage system. In addition, the number of stages is also included in the latter study. The results are presented in terms of charts which may be adopted for the design of such systems.

ISSN:0737-3937    

DOI:10.1080/07373939308916928

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This work presents a method to predict the stress and breakage that is caused by the drying of hygros-copic materials. Stresses were predicted for a viscoclasic cylinder with the properties of extruded durum semolina, or pasta noodles. The stresses were calculated as functions of the transient moisture and tem-perature gradients in the material which were predicted for the combined processes of drying, tempering,and cooling. The time and radial position of failure were predicted based on failure data for extruded semolina.

ISSN:0737-3937    

DOI:10.1080/07373939308916929

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met the adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and the effect of misture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m3/s-m2. A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the aifflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.

ISSN:0737-3937    

DOI:10.1080/07373939308916930

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The Henderson's EMC model in modified form was used to fit the EMC data given by Engelset al(1987) for brown, parboiled rice. The constants in the model were related to temperature. A method to find an expression for heat of vapourization of moisture from grain was developed and demonstrated using the EMC data of brown, parboiled rice. The heat of vapourization of moisture from rice was high at low moisture contents. For moisture contents above 25% (db), the moisture inside the grain behaved almost like free water.

ISSN:0737-3937    

DOI:10.1080/07373939308916931

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A one dimensional heat and mass transfer analysis is employed to predict the temperature distribution in the dry layer of a frozen food sample in the form of a slab undergoing freeze drying. The method avoids the use of the effective diffusivity and the Knudsen diffusivity, both parameters dependent upon the stnrcture of the food product. The accu acy of the numerical solution is validated with published data as well as data of present study obtained for the freeze drying of yoghurt. The predicted surface temperature of the food sample is in good agreement with the experimental data. Energy supplied to product surface through conduction across evacuated head space was found to be significant. The model is useful for the analysis of freeze drying of a food product.

ISSN:0737-3937    

DOI:10.1080/07373939308916932

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373939308916933

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373939308916934

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373939308916935

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0737-3937    

DOI:10.1080/07373939308916936

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor