Methodology to Obtain True Thermal Conductivity of Low Porosity Food Powders

Abstract

ABSTRACT: A technique was developed to measure, at a porosity close to zero, the true thermal conductivity of food powders. Samples of low porosities were prepared by mechanically compressing the food powder using a hydraulic press at pressures up to 3.035 × 105 kPa (abs) in specially designed stainless steel cylinders with a dummy probe in place. Variation in porosity of the samples was less than 5%. Thermal conductivity was measured as a function of porosity (0.086 to 0.7), moisture content (0 to 37%, dry basis), and temperature (30 to 150 °C) by the thermal conductivity probe method. The thermal conductivity values decreased with an increase in porosity and increased with an increase in moisture content and temperature.