摘要:

The PSI-Cell model is used to predict flow patterns and drying rates for laboratory-scale spray dryers. The liquid feed is water, with atomization producing a spectrum of droplet sizes. An analysis of the cause-and-effect relationships determining droplet trajectories, temperature fields, the location and magnitude of the backflow recirculation effect, and drying rates provides insight into the factors governing spray-air contacting and dryer performance. Independent effects are assessed for spray angle, dryer column diameter, initial droplet size distribution and droplet velocity (separately and as linked through atomizer pressure), air/water flow ratio, and liquid volatility. Inferences are made for effective dryer design, selection of operating conditions, and logic for scale-up.

ISSN:0737-3937    

DOI:10.1080/07373939108916639

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A general dynamic model for a cross-flow dryer is developed from fundamental balance equations. Six dimensionless groups that govern the process are defined and the resulting dimensionless equations are solved with the method of lines, using the Advanced Continuous Simulation Language software package ACSL (1986). The mesh influence on the numerical solution is investigated, and the assumption of quasi-steady state for the air is discussed. Application of the model to rice-drying experiments shows good agreement, and the results underline the potential of the model and the numerical solution strategy in obtaining critical physical insight towards the operation of cross-flow rice dryers.

ISSN:0737-3937    

DOI:10.1080/07373939108916640

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A model has been developed to simulate fixed-bed drying of crop particles with randomly distributed average particle moisture contents. A lumped model approach was used to derive a set of ordinary differential equations that predict the distribution of average particle moistures and temperatures, as well as the air humidity and temperature versus time and position within the dryer. The equations were solved numerically, and predicted results compared well with experimental data for English walnuts.

ISSN:0737-3937    

DOI:10.1080/07373939108916641

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A continuum model of equilibrium drying processes developed by Ilic and Turner [6], [19] is reformulated in such a way that the source terms are absent. The model is also extended by including a jump through the hysteresis formed by the wetting and drying curves. The jump is expressed in terms of Heaviside unit function. When the unit function is approximated by a sequence of functions, a single system of three coupled nonlinear partial differential equations results. The system is solved numerically using finite difference

ISSN:0737-3937    

DOI:10.1080/07373939108916642

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The thermodynamic analysis of the water-foodstuff equilibrium is reviewed, showing how partial molar and integral enthalpies and entropies can be obtained and indicating how to manipulate the experimental data for this purpose. The need for accurate and precise data is stressed and one experimental approach is recommended. Experimental results of desorption of water from Granny Smith apples provide information which is consistent from the thermodynamical standpoint. It is noted that the value of monolayer thickness corresponding to a minimum in integral entropy is substantially different from the value predicted by the BET equation.

ISSN:0737-3937    

DOI:10.1080/07373939108916643

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Transport processes in inhomogeneous bulk materials are described and experimentally investigated by means of moisture measurement by an electrolytic conductivity method.

ISSN:0737-3937    

DOI:10.1080/07373939108916644

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An experimental study of the residence tine distribution and drying characteristics of a continous pilot-plant vibrated fluidized bed dryer(the air distributor plate is 1.50 m in length and 0.24 m in width) is presented and discussed. Operating variables in the study included: vibration intensity, mass flow rate of air, granules feed rate, inlet air temperature and particle size. It was inferred from the experimental results that the flow of particles in the continous VFB could be considered as plug flow. Among the variables considered, vibration intensity was identified as the most significant factor to affect particle mean residence time, particle diffusivity and constant drying rate for the bed of wheat particulates and instant pharmaceutical BYN granules.

ISSN:0737-3937    

DOI:10.1080/07373939108916645

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

As the main condition of good wood drying is the uniformity of air velocity on the pieces, we focus in this paper on the problem of air flow in a wood drier loaded with stacks of planks. The case of the upper ventilation is mainly considerad A numerical study, based on the. resolution of movement equations for a turbulent flow, concerns the inlet and outer part of the stack. The result helped us to understand the part played by the space on each side of the stack, which differs for large or narrow distances from the wall. An experimental study gave us values for velocity distribution in the stack for given geometrical ratio of the drier and led us to recommend some rules for good loading.

ISSN:0737-3937    

DOI:10.1080/07373939108916646

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper evaluates the atmospheric drying of particulate material, such as coir dust or milled peat. in flat beds ( spreads). A mathematical model is presented that defines the relationship between the optimum yield of product and the prevailing weather conditions. A method is presented that enables the production manager to establish the optimum crop yield for a given drying cycle. When applied to milled peat. this method has shown a yield increase in excess of 10%.

ISSN:0737-3937    

DOI:10.1080/07373939108916647

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Development of a facility for generating monosized stream of droplets is described in the paper. The technique is based on transverse vibration of a hypodermic needle in which liquid fuel is introduced. This leads to production of drops at a regular frequency. The stream is produced using three types of fuel viz. methanol, aviation kerosene and n-hexane. Information on drop diameters, interdrop distance, drop trajectory is obtained experimentally. Experimental parameters governing the production of a good quality stream have been identified. Experimentally obtained trajectory of the stream is compared with results obtained from a theoretical model.

ISSN:0737-3937    

DOI:10.1080/07373939108916648

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor