摘要:

A numerical investigation was conducted to study two-dimensional heat and mass transfer during convective drying of clay brick. The set of macroscopic equations takes into account the effect of gaseous pressure. The established numerical code has allowed us to determine effects of the surrounding air conditions (temperature, pressure and vapor concentration) on drying Kinetic and on space-time evolution of the state variables (temperature, gaseous pressure, and liquid saturation).

ISSN:0737-3937    

DOI:10.1080/07373930008917783

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Rough rice at about 21% (wet basis) was dried at various conditions of temperatures and evaporating capacities of air. The influence of both parameters on drying rate has been studied. At high temperatures, high drying rates can be achieved with low evaporating capacities. In addition, desorption isotherms of rough rice were measured at 35, 60 and 85°C and the experimental isotherms data were fitted using a modified Pfost equation.

ISSN:0737-3937    

DOI:10.1080/07373930008917784

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Drying of forestry biomass in a rotary dryer has been performed. The raw material used wasErica Arboreabelonging to theever-green, broad leaves ecosystemwhich covers Central Greece and other Mediterranean countries. The study was part of a project concerning a Greek biomass pyrolysis demonstration plant where drying of biomass is very important in the contribution to the global energy balance and product yields of pyrolysis.

ISSN:0737-3937    

DOI:10.1080/07373930008917785

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In the production of MDF, wet resinated fibre must be dried to its target moisture content, normally 9 to 11%, before compaction into a board by hot pressing. Fibre drying can be interpreted as an incorporated process involving gas-solid two phase-flow, inter-component transfer, and heat and mass transfer within the fibre. Based on these mechanisms, a mathematical model has been developed to simulate the MDF fibre drying process. From the model, fibre moisture content, air temperature and air humidity along the dryer length can be predicted and factors affecting the drying rate examined. The model can be employed to optimise drying conditions and to evaluate improvements in dryer design. A case study of drying improvement in reduction of dryer emissions and heat consumption is given to demonstrate the potential application of the developed dryer model.

ISSN:0737-3937    

DOI:10.1080/07373930008917786

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

By using sorption data for com in the range of 4.4-60°C, the temperature (T) variations of the GAB. model parameters (Mm, CBand k) were studied. As only the monolayer moisture (Mm) varied (decreased) with temperature, a generalized GAB equation of four total parameters was obtained. This, together with the Clapeyron equation allowed a method to calculate the heat of sorption (Lb) as a function of T and moisture content (M). For each temperature, Lb presented a maxinuin some 30% above the heat of vaporization of water (Lf), which occurred around the Mm, in congruence with the sorption theory. A similar behavior of Lbwas found using the Othmer method. In contrast, the Gallaher equation predicted an ever increasing Lbup to 3 Lfat very low moistures. The GAB-Clapeyron method is then proposed to calculate Lbas a function of M and T.

ISSN:0737-3937    

DOI:10.1080/07373930008917787

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Effect of initial moisture content on the thin layer drying characteristics of hazelnuts during roasting was described for a temperature range of 100-160°C, using several thin layer equations. The effective diffusivity varied from 2.8×10−7to 21.5×10−7m2/s over the temperature and moisture range. Temperature dependence of the diffusivity coefficient was described by Arrhenius-type relationship. The activation energy for moisture diffusion was found to be 2703 kJ/kg, 2289 kJ/kg and 2030 kJ/kg for the initial moisture content of 12.3% db, 6.14% db, and 2.41% db, respectively. Two-term equation gave better predictions than Henderson and Pabis and Thompson equations, and satisfactorily described thin layer drying characteristics of hazelnut roasting. A generalised mathematical model with the linear temperature dependence for moistured, non-treated and pre-dried hazelnuts were also developed.

ISSN:0737-3937    

DOI:10.1080/07373930008917788

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In a batch experimental equipment, the behavior of a sawdust dryer in a vibrating fluidized bed is analyzed. Empirical data concerning fluidization velocities, pressure drops and drying kinetics was obtained, and advantages of using vibration in the drying chamber, relative to a conventional fluidized bed, are shown. This technique is presented as an alternative to solve problems of solid agglomeration and bed defluidization. Results show that it is possible to dry sawdust with more than 2 kg/kg moisture, in a vibrating bed keeping a high degree of bed homogeneity and high quality of fluidized state.

ISSN:0737-3937    

DOI:10.1080/07373930008917789

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Drying schedules applied in kiln drying, especially for hardwood species should be supplemented with values of air velocity. When dryers have no air velocity control their drying schedule can be suitably corrected. The correction should take into account factors related to dried material, i.e. wood moisture content, timber thickness, dried timber volume and primary width of a stack. Drying efficiency may be the criterion of modifications. The applied procedure of drying efficiency calculations lets to determine quantitative relationships between process and material factors.

ISSN:0737-3937    

DOI:10.1080/07373930008917790

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In a recent article, Baker described a novel technique for estimating the energy consumption of well-mixed fluidized bed dryers based on the use of experimental drying curves. An integrated approach to performing sizing and energy consumption calculations for such dryers using this technique is described in the present paper. A computer program, which includes not only the dryer simulator but also a heat recovery module and an exhaust air recycle option, is used to evaluate the viability of different energy-conservation strategies. The effects of operating parameters such as bed temperature, solids loading and air velocity on energy consumption and bed area are also explored. The observed drying kinetics are shown to have a major effect on the optimal design and operation of the dryer.

ISSN:0737-3937    

DOI:10.1080/07373930008917791

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Depending on the size and shape of the materials, methods employed to achieve effective fluidization during fluid bed drying varies from use of simple hole distributors for small, light weight materials to special techniques for larger and/or moist materials. This paper reviews common air distributors used in fluidized bed drying of food particulates. Also it reviews special methods of fluidizing larger irregular food particulates.

ISSN:0737-3937    

DOI:10.1080/07373930008917792

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor