Measured and predicted temperatures in a grain processing building under heat treatment – 1. Temperature profiles during heat treatment

Abstract

Temperature gradients in the vertical direction decreased with increasing height. The maximum and mean temperature gradients above the surface of the concrete floor, in the absence of grain, were 5.4°C/cm and 3.6±0.0°C/cm; respectively. The room temperatures at higher locations varied less than those at lower locations. Moreover, after the surface grain temperature reached 97% of its maximum temperature, it was influenced by the local temperature and periphery configuration. Key words: Heat treatment, grain-processing building, temperature.Le traitement thermique est une méthode efficace de lutte contre les insectes ravageurs dans les installations de transformation des céréales. Pendant un traitement thermique dans un entrepôt de farine, nous avons mesuré les températures ambiantes ainsi que celles du blé, de l'avoine, de farine de blé et de farine d'avoine, soit en tas ou en tubes de 0,15 m de hauteur, sur un plancher de béton à l'intérieur de l'entrepôt tout au long des 20 heures du traitement. Les températures ambiantes à divers endroits avaient la même distribution dans le sens vertical, malgré la présence de ventilateurs à différents endroits de la salle. Les gradients de température dans la direction verticale ont diminué avec la hauteur. Le maximum et la moyenne des gradients de température au-dessus de la surface du plancher de béton, sans grain, étaient de 5,4 °C / cm et 3,6 ± 0,0 °C / cm; respectivement. Les températures ambiantes aux endroits les plus élevés variaient moins que celles aux endroits moins élevés. De plus, après que la température du grain de surface ait atteint 97 % de sa température maximale, elle a été influencée par la température locale et la configuration périphérique. Mots clés: traitement thermique, installations de transformation des céréales, température.

Measured and predicted temperatures in a grain processing building under heat treatment – 2. Mathematical modeling of heat and mass transfer during heat treatment

“…The measured temperatures (Jian et al 2012) at the concrete surface, middle of the grain piles or tubes, and the surface of the grain mass were compared with the temperatures predicted by the developed models. The residues between measured and predicted temperatures were used to verify and validate the developed models.…”

“…Brijwani et al (2010) also found that floors covered with 0.02 m deep flour took 1 to 5 h longer to reach 50°C than floors with thin flour dust. The setup of the experiment was slightly different than that used in this experiment (Jian et al 2012). The former had the flour inside a plastic box with a lid.…”

“…To find the coefficient of diffusion, about 15 kg wheat and oats (the same grain as used in the heat treatment experiment) were put in metal tubes [the same as in Fig. 1 of Part I in this study (Jian et al 2012)]. The bottom of the tube was set on 0.35 m Styrofoam.…”

“…The aim of this study was: 1) to develop finite difference models to predict the temperatures of concrete floors with or without grain; 2) verify and validate the developed models using the measured temperatures in part I of this study (Jian et al 2012); and 3) to predict floor temperature under different assumptions.…”

“…In Part 1 of this study (Jian et al 2012), air, grain, and concrete floor temperatures were measured in a flourmill storage building during heat treatment. The concrete floor was the coldest spot, and the vicinity temperature and grain covering influenced the temperature.…”