Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
COEFFICIENT ESTIMATION FOR HEAT TRANSFER ON VEGETABLE MACROPOROUS MEDIA
Submission Author:
Paulo Smith Schneider , RS , Brazil
Co-Authors:
Ana Urquiola, Graciela Alvarez, Denis Flick, Pedro Curto-Risso, Paulo Smith Schneider
Presenter: Paulo Smith Schneider
doi://10.26678/ABCM.COBEM2017.COB17-1354
Abstract
This paper presents two methods to identify heat transfer coefficients for stored bulk frozen vegetables. Product and air into a pallet are modeled as a macroporous media, submitted to natural air flow. Thermal conductivity and convective coefficients are obtained by a combination of experimental measurements and numerical simulation for two frozen products: slices of carrots and extra thin green beans. Values are compared to literature sources and among them. The calculated equivalent thermal conductivities are 0.14 Wm-1K-1 for carrot slices and 0.10 Wm-1K-1 for green beans, which differs less than 10% to the correspondent literature values of 0.13 Wm-1K-1 and 0.09 Wm-1K-1, obtained with the Kupriczca’s correlation for a macroporous media compound by spheres. Convective coefficient for carrot slices and green beans are estimated as 2.4 Wm-2K-1 and 2.3 Wm-2K-1, respectively, within the expected values calculated with different correlations from literature. The proposed methods are a simple and good tool to obtain an order of magnitude for these coefficients. Coefficients are similar for both porous media, even though they display different geometries. The equivalent conductivity for carrots was 28.5% bigger than for green beans, since its porosity (0.55) was smaller than for green beans (0.65). The convective coefficients were very close for both products, but a slightly higher for carrots (7%).
Keywords
vegetable freezingmacroporous media, thermal conductivity, porous media natural convection
