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a b s t r a c tIn this work the simulation of velocity and temperature distributions inside a refrigerated vehicle is evaluated. For this purpose a 3D double distribution lattice Boltzmann method (LBM) with the Bhatnagar-Gross-Krook (BGK) collision operator is coupled by the buoyancy force calculated with the Boussinesq approximation. This LBM is extended by a Smagorinsky subgrid method, which numerically stabilizes the BGK scheme for low resolutions and high Reynolds and Rayleigh numbers. Besides validation against the two benchmark cases porous plate and natural convection in a square cavity evaluated at resolutions of y + ≈ 2 for Ra numbers between 10 3 and 10 10 , the method and its implementation are tested via comparison with experimental data for a refrigerated vehicle at Re ≈ 53 000.The aim of the investigation is to provide a deeper understanding of the refrigerated vehicle's insulation processes including its thermal performance under turbulent flow conditions. Therefore, we extend this method by the half lattice division scheme for conjugate heat transfer to simulate in the geometry of a refrigerated vehicle including its insulation walls. This newly developed method combination enables us to accurately predict velocity and temperature distributions inside the cooled loading area, while spatially resolving the heat flux through the insulation walls. We simulate the time dependent heating process of the open door test and validate against measurements at four characteristic velocity and 13 temperature positions in the truck. (M. Gaedtke). are complex material requirements which, in addition to the insulation, include static stability, load securing as well as resistance against vibrational stress.According to Smale [2] most simulations and models for the representation of a velocity and temperature distribution in the field of applied cooling of geometries between 1974 and 2006 have shown low accuracy and large deviations from experimental data. Tabsoba et al. [3] studied the influence of the k-ϵ turbulence model against the Reynolds stress model, where they indicated the k-ϵ model to fail at the prediction of certain flow characteristics in ventilated enclosures. Ambaw [4] summarized studies on the cooling of harvested food, indicating some progress being made between 2006 and 2013 with the accuracy of the models. With simulations mainly based on Reynolds averaging turbulence models as the k-ϵ or shear stress transport (SST) model [5][6][7][8], he also came to the conclusion, that a clear increase in the accuracy of turbulent 3D simulations within complex cooled geometries compared with experimental data has still to come.According to James [9] first simulations of the open door tests have been carried out by Tso et al. [10]. Tso's simulated temperatures deviate from experimental recordings by up to 4 K at a temperature difference of about 26 K. Son [11] showed an approximation to the validation data up to 1.13 K in the simulation of the velocity and temperature distribution in the interior of a filled...

Due to reduced thermal conductivity, vacuum insulation panels (VIPs) provide significant thermal insulation performance. Our novel vacuum panels operate at reduced pressure and are filled with a powder of precipitated silicic acid to further hinder convection and provide static stability against atmospheric pressure. To obtain an in depth understanding of heat transfer mechanisms, their interactions and their dependencies inside VIPs, detailed microscale simulations are conducted.Particle characteristics for silica are used with a discrete element method (DEM) simulation, using open source software Yade-DEM, to generate a periodic compressed packing of precipitated silicic acid particles. This aggregate packing is then imported into OpenLB (openlb.net) as a fully resolved geometry, and used to study the effects on heat transfer at the microscale. A three dimensional Lattice Boltzmann method (LBM) for conjugated heat transfer is implemented with open source software OpenLB, which is extended to include radiative heat transport. The infrared intensity distribution is solved and coupled with the temperature through the emissivity, absorption and scattering of the studied media using the radiative transfer equation by means of LBM. This new holistic approach provides a distinct advantage over similar porous media approaches by providing direct control and tuning of particle packing characteristics such as aggregate size, shape and pore size distributions and studying their influence directly on conduction and radiation independently. Our aim is to generate one holistic tool which can be used to generate silica geometry and then simulate automatically the thermal conductivity through the generated geometry.

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The development of sustainable trucks has drawn a lot of attention lately. However, the reduction of fuel consumption and emissions related to deep frozen food transports has not yet been satisfactorily considered. In this paper, a thermal Large Eddy Lattice Boltzmann Method (LES-LBM) is applied to investigate two concepts for optimized refrigerated vehicles: (a) the inclusion of vacuum insulation panels (VIP) in the refrigerated body's walls and (b) the introduction of a latent heat storage (LHS) to exchange fuel-driven air conditioning (AC), both with conveniently worth while potential to decrease fuel consumption and related emissions. The present numerical method allows for an accurate and efficient transient conjugate heat transfer simulation including the spatial and temporal resolution of the temperature distribution inside the insulation walls and the cargo in addition to the turbulent surrounding air flow induced by the AC. The present concept of VIP inclusion is found capable of halving the required cooling energy. In addition, it effectively reduces the variations in the temperature of the chilled goods during cooling operation, which is an important measure of the quality of the refrigerated body. The reduced required cooling energy is further found to enable the AC system to be replaced by a LHS mounted near the top of the refrigerator body and an additional ventilation system of lower total capacity. A comparison between simulations with conventional AC and LHS is conducted concerning the temperature homogeneity of loaded deep frozen food products. It is shown that a slight flow around the refrigerated goods is necessary and the maximum downtime of the AC system is 8 min in case of combined PUR and VIP insulation and 11 min in case of an additional LHS.