Effect of concentration and temperature on the thermal conductivity of frozen acerola pulp

Abstract

The purpose of this work was the experimental determination of the thermal conductivity of acerola pulp at concentrations of 5.5, 7.5, 9.5, 11.5 and 13.5 °Brix and temperatures of 0, –5, –10, –15, –20, –25 and –30 °C. The methodology used involved a hot wire probe, and the experimental results were compared with values estimated by several theoretical models (series, parallel and Maxwell-Eucken models) to evaluate the error involved. We observed an influence both of the concentration and the temperature on the thermal conductivity of the pulp. An increase of the conductivity with a decrease in temperature and in the solids concentration was detected. We observed the greatest increases in the range of 0 to –10 °C. Linear and polynomial equations were adjusted for the direct determination of the thermal conductivity of the pulp in the range of temperature and concentration studied.