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A number of contributions have been made in the field of chemical process monitoring and control with applications ranging from simple flow and temperature control to highly complex inferential adaptive control systems in biochemical and polymer production. These technologies face difficulties when applied to drying equipment, due to the inherent complexity of the operation. This article shows some recent trends in monitoring and control of drying processes. This review is organized in sections according to the transport phenomena involved in the operation of a dryer. In each section, examples of recent trends in monitoring and control strategies of key variables directly related to these transport phenomena are discussed. [ABSTRACT FROM PUBLISHER]

The objective of this work was to experimentally determine physical properties such as apparent densities, real densities, and porosity of freeze-dried tropical fruits pulps such as pineapple, Barbados cherry, guava, papaya, and mango, and to carry out nutritional analysis of vitamin C, calcium, and phosphorus in the freeze-dried and in natura pulps. The freeze-dried pulps presented low apparent density and elevated values of true density and porosity. Based on the nutritional analysis performed in the in natura and freeze-dried pulps the preservation of product quality was verified. [ABSTRACT FROM AUTHOR]

The dimensionless vibration number (Γ) is the parameter most widely applied to quantify the vibration energy of a vibro-fluidized bed. It is defined as a function of the amplitude (A) and of the frequency of vibration (f). Most works in literature present their results as a function of Γ, which is adopted as a single parameter to explain the results on fluid dynamic behavior of vibro-fluidized beds, independent on the magnitudes of A and f. From its definition, however, it is possible to obtain identical values of Γ just by combining different values of A and f, and further studies are necessary for a better analysis of fluid dynamic behavior of vibro-fluidized beds concerning their vibration energy. Therefore, in this work the effects of dimensionless vibration number on the fluid dynamic behavior of a vibro-fluidized bed will be investigated by choosing different combinations of A and f values arranged to provide identical values of Γ. The tests were carried out for dry and wet beds, for values of Γ = 0.0 (fluidized bed), 1.0, 2.0, and 4.0. The results indicate that Γ must be used carefully when applied as the only parameter to characterize the vibration effects in a vibro-fluidized bed since very different fluid dynamic behavior was detected at a fixed Γ at different amplitudes and frequencies. [ABSTRACT FROM AUTHOR]

Drying kinetics of soybean seeds were investigated in the fixed bed (which is normally used) and in the moving bed with cross flow, both being run under thin-layer conditions. The analysis of the available data followed the diffusive model approach with re-parameterization. Special attention has been given to the nonlinearity inherent in the database in order to evaluate the statistical properties of the least squares estimator. The results showed that the effective diffusivity of the moving bed is 24 to 44% higher than that of the fixed bed. [ABSTRACT FROM AUTHOR]