Study of mathematical models of the specific mass of cajá pulp to determine the coefficient of thermal expansion

Abstract

Knowledge the thermophysical characteristics fruit pulp, such as specific gravity, is essential in modeling, simulation, and optimization studies industrial processes. Therefore, objective this work was determine a mathematical model to describe behavior the specific mass cajá pulp at different temperatures (10 to 70°C) and concentrations (7.5; 11 and 14.5 °Brix) and obtain the equation describe the coefficient thermal expansion. The analyzes specific mass cajá pulp were carried out using a pycnometer. The temperature was controlled by thermostatic bath, and concentration soluble solids was determined with aid a portable refractometer. Polynomial mathematical models used were adjusted the specific mass data as function temperature (°C) and concentrations (ºBrix), while thermal expansion coefficient equation (β) was determined using a thermodynamic expression. Average values specific mass cajá pulp depending on temperatures and concentrations of soluble solids ranged from 990.55 to 1050.12 kg.m-3. The specific mass values decreased significantly with increasing temperature and increased with increasing concentration. Model that best adjusted determine the coefficient thermal expansion was the second-grade model with a coefficient determination greater than 0.99. Such results could be useful design thermal processing and development of new technologies using cajá pulp.