Characteristics of sunflower seed drying and microwave energy consumption

Abstract

A b s t r a c t. The effect of the microwave-convective drying technique on the moisture ratio, drying rate, drying time, effective moisture diffusivity, microwave specific energy consumption, and energy efficiency of sunflower seeds were investigated. Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in the drying time. The drying data were fitted to four thin-layer drying models. The performance of these models was compared using the coefficient of determination, reduced chi-square and root mean square error between the observed and predicted moisture ratios. The results showed that the Page model was found to satisfactorily describe the microwave-convective drying curves of sunflower seeds. The effective moisture diffusivity values were estimated from Fick diffusion model and varied from 1.73 10 -7 to 4.76 10 -7 m 2 s -1 . Increasing the microwave power resulted in a considerable increase in drying efficiency and a significant decrease in microwave specific energy consumption. The highest energy efficiency and the lowest microwave specific energy consumption were obtained at the microwave power of 300 W.K e y w o r d s: drying, modelling, sunflower seed, microwave energy consumption

Suitable model for thin-layer drying of root vegetables and onion

“…However, the models discussed are time consuming because the diffusion equations governing the process are complicated (Kaleta and Górnicki, 2010b). Theoretical models have been applied to describe the drying kinetics of such biological materials as apples (Kowalski and Rybicki, 2017), carrots (Mahapatra and Tripathy, 2018;Sánchez-Sáenz et al, 2015), cherry tomato (Bennamoun et al, 2015), green bean (Doymaz et al, 2015;Tekin et al, 2017), hazelnut (Giraudo et al, 2018), peach (Doymaz, 2014), pumpkin (Agrawal and Methekar, 2017;Junqueira et al, 2017), peppermint leaves (Ashtiani et al, 2017), poppy seeds (Stakić and Urošević, 2011), pre-gelatinized potato starch (Jiang et al, 2017), red beets (Kaleta and Górnicki, 2010b), spinach leaves (Doymaz, 2009), and sunflower seeds (Darvishi et al, 2013).…”

Intensification of the drying process of small seed oilseeds using microwave electromagnetic radiation

“…During infrared drying (thermal radiation), the rays are absorbed by the product, which ensures a more uniform heating of the material in depth compared to convective drying (Rogov, 1988). This, in turn, leads to a decrease in the temperature gradient and direct transfer of steam from inside to outside under the influence of the gradient of total pressure (Darvishi et al, 2013;Béttega et al, 2014;Zhao et al, 2017). It should be borne in mind that increasing the temperature of infrared heating can lead to damage to the grain germ.…”

Comparison of Mathematical Equation and Neural Network Modeling for Drying Kinetic of Mendong in Microwave Oven

“…Each equation of models is categorize as: a) theoretical models, suggest that the moisture transport is controlled mainly by internal moisture mechanism and needs assumption of geometry of the food material, mass diffusivity and heat conductivity [6]; b) semi theoretical models, consider only the external resistance to the moisture transport and are valid only in the specific range drying conditions [5]; and c) empirical models, derive a direct relationship between average moisture content and drying time, they neglect fundamentals of the drying process and their parameters have no physical meaning [6]. During the drying process, diffusivity is assumed to be the only physical mechanism for the transfer of water to material surface and can be defined by Fick's second law of diffusion as follows [7]:…”

“…Drying process in a microwave oven has an advantage in terms of drying rate, energy efficiency, product quality, and efficiency in the utilization of space [6]. Several studies have been conducted to test the drying process of agricultural products through the use of microwave heating, such as the foot elephan yan (Amorphophallus paeoniifolius) [6], carrots [7], lemon [8], and durian [9].…”