Espectroscopia fotoacústica aplicada à determinação da efusividade térmica de polpas de frutas.

Abstract

In the present work the Photoacoustic Spectroscopy technique (PAS) was applied to measure the thermal effusivity of pulps of fruits. Six types of samples (in nature) 6mm diameter and 1mm thickness were prepared in the form of a disc for PAS experiments: mango, banana, apple, guava, papaya and pineapple. The thermal effusivity values were determined using the (BALDERAS-LOPEZ et al., 1995) method. In the mango pulps and papaya thermal effusivity values of 1369 W.s1/2.m"2.0C"1 and 1267 W.s1 / 2.m"2.°C\ respectively, with differences of 6,55% and 5,05% in relation to the values of the literature. Banana's pulps, apple and pineapple presented values of thermal effusivity of 1667 W.s1 / 2.m-2.°C"\ 1666 W.s^m'^C1 and 1765 W - s ^ j n ^ C 1 , respectively, with percentile differences of 40,79%, 50,23% and 50,21%, that they are little above in relation to the values of the literature, due to different varieties of 1 /2 2 0 1 the products. The value found of thermal effusivity, 2535 W.s .m" . C" for the guava pulp, is above the value of the literature presenting a percentile difference of 93,66%. This difference has been attributed to the possible dysfunction of the system caused by the red wavelength used in this work.