Effect of Air Velocity and Temperature on the Drying Kinetics of Drumstick Leaves (Moringa Oleifera)

Abstract

The present study examines the effect of air velocity on drying kinetics of the drumstick leaves in a forced convective dryer. The drumstick leaves were dried in the temperature range of 50–800 C, at different air velocity (Dv) of 0.5 and 1.3 m/s. The results indicated that drying temperature and air velocity are the factors in controlling the drying rate. Experimental data obtained for the samples for color, drying rate and drying time proved that air velocity of 1.3 m/s yielded the product superior in terms of both quality and energy efficiency as compared to the samples at 0.5 m/s. Activation energy for drumstick leaves dried with air velocity, 0.5 and 1.3 m/s was 12.50 and 32.74 kJ/mol respectively. The activation energy relates similarly with the effective moisture diffusivity which also increased with increase in air velocity and temperature.

Thin‐layer drying behavior of West Indian lemongrass (Cymbopogan citratus) leaves

“…The effect of temperature on the moisture content decline of other leafy materials has also been reported for other leafy materials such as coriander, bay leaves, olive, and drumstick ( Moringa oleifera ) leaves (Ahmed et al., ; Demir et al., ; Doymaz, ; Erbay & Icier, ; Premi, Sharma, & Upadhyay, ). Higher temperatures cause a higher reduction in moisture content as a result of increased heat and mass transfer, which favors evaporation of moisture from the leaves (Aghbashlo, Kianmehr, & Hassan‐Beygi, ; Doymaz, ).…”

“…Coradi et al (2014) calculated diffusion coefficients of lemongrass leaves based on the constants (k) obtained from fitting the data to the two-term model and found values to increase from 2.5 to 4.5 × 10 −11 m 2 /s as temperature increased from 40 to 70°C. For other leafy materials, researchers have also reported an increase in diffusions coefficients with increasing temperature in mint, bay leaves, olive leaves, spinach, verbena, and fever leaves with values in the order of 10 −12 to 10 −8 m 2 /s (Barbosa et al, 2007;Cakmak et al, 2013;Doymaz, 2006Doymaz, , 2014Erbay & Icier, 2010;Premi et al, 2010;Simha & Gugalia, 2013;Sobukola & Dairo, 2007). Activation energy values for leaves such as mint, olive, and bay leaves have ranged between 31.79 and 62.93 kJ/mol (Barbosa et al, 2007;Cakmak et al, 2013;Doymaz, 2006Doymaz, , 2014Erbay & Icier, 2010).…”

“…The Midilli model has been reported to best describe the drying data for bay leaves, verbena leaves microwave-dried spinach leaves (Barbosa et al, 2007;Cakmak et al, 2013;Doymaz, 2014;Simha & Gugalia, 2013). The Page model has been reported to best describe the MR data for hot air-dried bay leaves, coriander, fever leaves, and spinach (Gunhan, Demir, Hancioglu, & Hepbasli, 2005;Shaw et al, 2007;Simha & Gugalia, 2013;Sobukola & Dairo, 2007) while the Verma, logarithmic, and two-term models were used in other studies (Doymaz, 2006;Kadam et al, 2011;Premi et al, 2010). Erbay and Icier (2010) reported that the modified Henderson and Pabis model TA B L E 6 (Continued) (Continues) best fits the MR data for olive leaves dried at 50 to 70°C at 0.5 to 1.5 m/s.…”

Optimization of an Air‐Drying Process to Obtain a Dehydrated Naranjita (Citrus Mitis B.) Pomace Product With High Bioactive Compounds and Antioxidant Capacity

“…Also, when high AV levels were used, the drying rate was increased, possibly due to a reduction in the external resistance to mass transfer caused by these conditions (Premi et al . ). The results are similar to those reported by Zlatanović et al .…”

Mathematical Modeling of Thin-Layer Solar Drying for Yarrow, Coriander and Hollyhock

“…The initial moisture content of hollyhock flowers usually is more than 90% (w.b.). Different types of dryers with different energy consumption range such as hot air dryer, vacuum dryer, freeze dryer, microwave dryer and fluidize bed dryer have been used to dehydrate medicinal plants [17][18][19][20][21]. Drying is a high-energy consumption process as 15% of total industrial energy in most industrialized countries is used for this process [24].…”