Analysis of heterogeneous cooling of agricultural products inside bins Part II: Thermal study

An experimental thermal study was performed in order to characterise heat transfer intensity for spherical objects packed in stacked bins and cooled by air forced convection. The heat transfer coefficient was measured for each sphere in a test bin using spherical sensors. Large differences in heat transfer coefficient values, up to 40%, were observed. This heterogeneity could be explained by the fact that the airflow is not uniform (cf. Part I). Each object was exposed to local airflow conditions (mean velocity and turbulence). A correlation was established between the local heat transfer coefficients and local airflow parameters. Cylindrical sensors were also constructed in order to measure the heat transfer coefficient inside packed spheres. The measurements correlated well with the spherical sensors for the same positions in the bins. (C) 1999 Elsevier Science Ltd. Ail rights reserved.