Thermal study of a transport container

A thermal study of a container for international transport has been carried out in order to determine the temperature distributions. Several experimental conditions such as cooling modes, the onset of defrosting, the existence of cargo inside the container and two varying set points have been evaluated. It was observed that the difference between the temperature inside the container and the set point raised up to 30% of ambient temperature. Moreover, it was observed that the modulated cooling allowed to obtain a more homogeneous refrigeration. However, temperature differences up to 8 °C were observed under on–off control cooling

Airflow pattern and temperature distribution in a typical refrigerated truck configuration loaded with pallets.

Abstract This work is part of a research activity aiming to improve and to optimise air-distribution systems in refrigerated vehicles in order to decrease the temperature differences throughout palletised cargos. This condition is essential in order to preserve the quality, safety and shelf life of perishable products. The present study reports on the numerical and experimental characterization of airflow within a semi-trailer enclosure loaded with pallets. The experiments were carried out on a reducedscale (1:3.3) model of a refrigerated-vehicle trailer. The performance of ventilation and temperature homogeneity were characterized with and without supply air duct systems. Both configurations are extensively used in refrigerated transport. The numerical modelling of airflow was performed using the Computational Fluid Dynamics (CFD) code Fluent and a secondmoment closure, the Reynolds stress model (RSM). The results obtained using the RSM model showed good agreement with the experimental data. Numerical and experimental results clearly show the importance of air ducts in decreasing temperature differences throughout the cargo

Modélisation numérique des écoulements et des transferts de chaleur dans un véhicule frigorifique chargé de palettes

The aim of ths study is to propose a model of flow and heat transfer in a semi trailer laden with pallets. The numerical resolution of the momentum and the energy equations is performed on a three-dimensional configuration by the finite-volume method with the Phoenics computer program. The stationary model takes into account the heat loss through walls. The results presented by the velocity and thermal fields allow to locate the critical regions where high temperature is caused by a bad air recirculation. The simulations show, at less qualitatively, a good agreement with experiments. They confirm the benefit of the air distribution device equipped in some refrigerated engines in order to assure a better temperature homogeneity. / L'objectif de cette étude est de proposer une modélisation des écoulements et des transferts thermiques dans une semi-remorque frigorifique chargée de palettes. La résolution numérique des équations du mouvement et de l'énergie est effectuée dans une configuration tridimensionnelle par la méthode des volumes finis sur le logiciel Phoenics. La modélisation est effectuée en régime permanent et prend en considération les pertes thermiques à travers les parois. Les résultats des simulations corroborent, au moins d'un point de vue qualitatif, les expérimentations qui ont été réalisées par ailleurs. Ils confirment l'intérêt des dispositifs de distribution d'air au plafond, qui équipent certains véhicules frigorifiques, sur la réduction de la dispersion des températures d'air au sein du chargement

Experimental characterization of heat transfer in a pallet of cheese

5th IIR Conference on Sustainability and the Cold Chain, Beijing, CHN, 06-/04/2018 - 08/04/2018International audienceDuring refrigerated transport and storage, cheese generates heat via respiration of the living microorganisms inside and at the surface of the product . In order to ensure the level and uniformity of temperature within a pallet, it is important to take into account this amount of heat. This work aimed to study the influences of different parameters on the heat transfer for which forced convection around the pallet interacts with free/mixed convection inside it. An experimental device was used in which the cheese was replaced by plaster blocs ; each bloc being equipped with a heating resistance to simulate the produce heat generation. The pallet was placed in a room under controlled operating conditions. Two upwind air velocities were selected : 0.31 m/s and 0.73 m/s ; the heat generating varied between 0.05W and 0.30W per product of 0.25k g. Adimensionless corr elation predicting the maximal temperature in function of the operating conditions was established

Influence of the discrete production term on the computation of turbulent flow in a stirred vessel

The present work is devoted to the prediction of the mean flow and turbulence properties in a baffled vessel equipped with a Rushton turbine

Numerical modelling of airflow and heat transfer in a vented pallet of cheese

Foodsim' 2018, Ghent, BEL, 08-/04/2018 - 12/04/2018International audienceDuring refrigerated transport and storage, cheese generates heat via respiration of the living microorganisms. Therefore, free/mixed convection phenomena are expected to occur within the pallet and to internet with forced convection around it. The resulting airflow should promote appropriate internal ventilation within the pallet to ensure the temperature homogeneity. This work aimed to study the influence of various parameters on the air flow and heat transfer within a pallet of cheese during forced air cooling. A 3-D computational fluid dynamics (CFD) model was developed to predict the temperature of the products in different configurations. Both forced and natural convection due to the heat generation of the produce were considered in the model. The numerical model can be potentially used as a design tool to improve the design of vented packages in order to reduce temperature differences of products within the pallet during the whole cold chain. (cooling, transport, storage

Influence of the discrete production term on the computation of turbulent flow in a stirred vessel

The present work is devoted to the prediction of the mean flow and turbulence properties in a baffled vessel equipped with a Rushton turbine