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Drying Models (drying + models)
Selected AbstractsEFFECT OF HIGH-PRESSURE PROCESSING ON TEXTURE AND DRYING BEHAVIOR OF PINEAPPLEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2009A.R.P. KINGSLY ABSTRACT The effect of high-pressure processing on texture and drying behavior of pineapple slices was investigated. Pineapple slices were high pressure processed at 50, 100, 300, 500 and 700 MPa at 25C for 10 min. The control, hot water-blanched and high-pressure processed samples were then dehydrated at 70C. Application of high pressure reduced the sample hardness, springiness and chewiness while it had no significant effect on cohesiveness of pineapple. Elevated pressure treatment (,500 MPa) reduced drying time more effectively than for the other pretreated samples. Experimental dehydration data were empirically fitted using six thin-layer drying models. Among the models tested, logarithmic model best described the drying behavior of pineapple slices. The effective moisture diffusivity was found to increase with an increase in the level of pressure up to 500 MPa, and the samples processed at 500 and 700 MPa had higher diffusivity values than blanched samples. PRACTICAL APPLICATIONS This work shows that high-pressure blanching of pineapple can be an alternative for hot water blanching, before dehydration. The results may find application in development of quality snack food from pineapple fruits. [source] THIN-LAYER DRYING KINETICS OF SESAME HULLS UNDER FORCED CONVECTION AND OPEN SUN DRYINGJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2007MAJDI A. AL-MAHASNEH ABSTRACT Sesame hulls are a useful by-product of the sesame processing industry. The sesame hulls are produced at a high moisture content (68% wet basis) and need further drying to prevent deterioration. In this study, both open sun drying (OSD) and forced convection drying (FCD) at 42, 55, and 76C and 1.2 m/s air velocity were investigated. Six common thin-layer drying models were fitted to the experimental data. Several statistical parameters were used to evaluate the performance of thin-layer drying models, including r2, x2, root mean square error (RMSE) and residuals. Sesame hull drying was found to take place completely in the falling rate region. The modified Page model was found to describe OSD data well, while the Wang and Singh model was the best model for describing FCD. Effective diffusivity was found to be 1.89 × 10 - 8 m2/s and 7.36 × 10 - 10 to 1.20 × 10 - 9 m2/s for OSD and FCD, respectively. Activation energy was also found to be 12.95 kJ/mol for FCD. [source] CHARACTERISTIC DRYING CURVE and MATHEMATICAL MODELING of THIN-LAYER SOLAR DRYING of PRICKLY PEAR CLADODE (OPUNTIA FICUS INDICA)JOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2004S. LAHSASNI ABSTRACT Thin-layer solar drying experiments were conducted for the prickly pear cladode grown in Marrakech, Morocco. the experimental drying curves obtained show only a falling rate period. the results verified, with good reproducibility, that the drying air temperature is the main factor in controlling the drying rate. the expression of the drying rate equation was determined empirically from the characteristic drying curve. Eight different drying models were compared according to their correlation coefficient (r2) to estimate solar drying curves. the Page model could satisfactorily describe the solar drying curves of cladode with an r2 of 0.9995. the coefficient of this model could be explained by the effect of drying air temperature with an r2 of 1.0000. [source] Vacuum drying of wood with radiative heating: I. Experimental procedureAICHE JOURNAL, Issue 1 2004Patrick Perré Abstract Experimental results for the vacuum drying of wood with radiative heating are presented. In particular, the temperature and pressure measurements at different locations within the board are provided, as are the overall drying curves. The heat source is such that the temperature at the end of the process remains low (,150°C), and under these conditions, the drying process resembles convective drying with superheated steam. Further important details concerning the internal transfer mechanisms that are induced by this drying process can be pointed out by comparing results for sapwood and heartwood of different species (Picea abies, Abies alba and Fagus silvatica). These extensive experimental data sets will be used in Part II of this work for the purposes of assessing the accuracy and predictive ability of two different drying models and for analyzing the vacuum drying process further at a fundamental level. © 2004 American Institute of Chemical Engineers AIChE J, 50:97,107, 2004 [source] Vacuum drying of wood with radiative heating: II.AICHE JOURNAL, Issue 1 2004Comparison between theory, experiment Abstract In part I of this work extensive experimental data sets for the vacuum drying of wood with radiative heating were presented for sapwood and heartwood of different species (Picea abies, Abies alba, and Fagus silvatica). These data sets are used here to validate two previously developed drying models. The first drying model, which is known as TransPore, is a comprehensive model able to capture the intricately coupled heat- and mass-transfer mechanisms that evolve throughout the drying process. The second model, which is known as Front_2D, uses a number of simplifying assumptions to reduce the complexity of the comprehensive model to a system that enables a semianalytical approach to be exploited for its solution. Although the first model provides a more accurate description of the entire process, the second model is able to produce representative solutions very efficiently in terms of overall computational times, making it a viable option for on-line control purposes. The comparison with experimental data highlights that both models are able to capture all of the observed trends, allowing them to be used with confidence for investigating the vacuum drying process at a fundamental level. The new contribution of this work lies in the fact that both models are used here for the first time to simulate drying at a reduced external pressure. © 2004 American Institute of Chemical Engineers AIChE J, 50: 108,118, 2004 [source] | ||||||||||