Analysis of the geometrical changes of celery in a test piece during convection drying
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Department of Machine Design, University of Agriculture, Balicka 104, 30-149 Cracow, Poland
Acceptance date: 2003-01-22
Int. Agrophys. 2003, 17(1): 19–23
The study has been devoted to change analysis of linear dimensions, surfaces and drying shrinkage rate, in the course of the convector drying of celery. It has been found that drying resulted in most significant changes of cube edges in their central parts. The shape of lateral surfaces of celery cubes changed from the originally square to irregular, resembling sandglass. In spite of this, the analysed characteristic linear dimensions altered in a nearly identical way. In the course of drying and the progressive reduction of water content, the characteristic linear dimensions and the surface of celery samples declined, while the drying shrinkage rate increased. The change rate of studied values depended on the appearance of the first and the second drying periods. No significant dependency was found between the temperature of drying medium (in the analysed measurement period) and the dynamics of surface change, linear dimensions alteration and shrinkage rate. Next, the studied values were used in the empirical verification of adopted theoretical models of celery drying kinetics, in the first and the second period of drying. Empirical verification confirmed the correctness of adopted mathematical models. The relative local error was no higher than 15%, while the global error did not exceed 2.5 %.