سیدرضی کریمی آکندی

Aloe vera plant (Aloe vera) from Liliaceae family is one of the high valuable medicinal plants. One of the usage the gel of the crop is to use the dried powder. In this research, drum dryer was used to dry the product. Finite element method was used to examine the heat transfer in the cylinder of a drum dryer. Four cylindrical models were used to study the uniformity and maximum heat transfer of steam flow to the dryer cylinder wall. Two parameters were considered for controlling the flow of hot steam inside the cylinder, i.e. the conical barrier at input and the output (narrow and wide). The A and B models are narrow and broad output respectively, both without conical barrier and the C and D models, are similar to the A and B models but including conical barrier. The effect of two mass flow rates of intake water vapor (1 and 2 kg/s) was also investigated on the models. The results were important in terms of uniformity and maximum heat transfer on the cylinder surface. The results showed that the installation of a conical barrier in the drum dryer causes to direct the hot steam to the drum walls immediately and causes to have the highest heat transfer, so that the temperature increase above 485 K. The barrier caused to move the steam near the drum wall from the beginning to the end. Meanwhile the temperature was cooled uniformly about 10 K. The lowest variation of temperature (6 K) on the cylinder wall was for the model B and mass flow rate of 1 kg/s, which the highest temperature (476 K) was at the middle of the cylinder, and the lowest temperature (470 K) was at the beginning as well as at the end of the cylinder.

Damask rose with scientific name of Rosa damascena Mill. contains essential oils with large medicinal properties. Qualitative and quantitative extraction of essential oils as well as its economic justification depends on appropriate methods of drying. Appropriate method of drying reduces loss and damage during storage and helps maintain product quality. The purpose of this study was to predict Rose moisture content during the drying process with hot air flowing as a function of temperature at four levels (40، 50، 60 and 70°C) and air velocity at three levels (0. 5، 1 and 1. 5 m/s)، using artificial neural networks. The average initial and final moisture contents were calculated to be 78% and 9%، respectively. The drying process was modeled by mathematical models using matlab and then the moisture content graphs were achieved by excel. Then، the drying process was modeled using neural networks with three inputs including temperature، air velocity and time. Results showed that neural network was more accurate than mathematic models in modeling and predicting the drying process of damask rose and could be used in on-line controlling.