9 research outputs found
Improvement of convective drying of carrot by applying power ultrasound. Influence of mass load density
[EN] Power ultrasound is considered to be a novel and promising
technology with which to improve heat and mass transfer phenomena
in drying processes. The aim of this work was to contribute to the
knowledge of ultrasound application to air drying by addressing
the influence of mass load density on the ultrasonically assisted air
drying of carrot. Drying kinetics of carrot cubes were carried out
(in triplicate) with or without power ultrasound application (75 W,
21.7 kHz) at 40 C, 1 m/s, and several mass load densities: 12, 24,
36, 42, 48, 60, 72, 84, 96, 108, and 120 kg/m3
. The experimental
results showed a significant (p < 0.05) influence of both factors, mass
load density and power ultrasound application, on drying kinetics. As
expected, the increase of mass load density did not affect the effective
moisture diffusivity (De, m2
/s) but produced a reduction of the
mass transfer coefficient (k, kg water/m2
/s). This was explained by
considering perturbations in the air flow through the drying chamber
thus creating preferential pathways and, as a consequence, increasing
external mass transfer resistance. On the other hand, it was
found that the power ultrasound application increased the mass
transfer coefficient and the effective moisture diffusivity regardless
of the mass load density used. However, the influence of power ultrasound
was not significant at the highest mass load densities tested
(108 and 120 kg/m3
), which may be explained from the high ratio
(acoustic energy/sample mass) found under those experimental
conditions. Therefore, the application of ultrasound was considered
as a useful technology with which to improve the convective drying,
although its effects may be reduced at high mass load densities.The authors acknowledge the financial support of the Spanish Ministry of Science and Technology (DPI2009-14549-C04-04) and the Universidad Politecnica de Valencia (PAID-06-08-3180).Cárcel Carrión, JA.; García Pérez, JV.; Riera, E.; Mulet Pons, A. (2011). Improvement of convective drying of carrot by applying power ultrasound. Influence of mass load density. Drying Technology. 29(2):174-182. https://doi.org/10.1080/07373937.2010.483032S17418229