Energy and Thermal Management, Air-Conditioning, and Waste Heat Utilization by Christine Junior & Oliver Dingel

Author:Christine Junior & Oliver Dingel
Language: eng
Format: epub
ISBN: 9783030008192
Publisher: Springer International Publishing

1.1 Modeling Approach

In this work, a simple modeling approach working with one mass averaged cabin air temperature is proposed. This average air temperature serves as a reference for the heat transfer computations at the inside surfaces due to convection as well as for the energy distribution into 12 predefined zones. On the one hand, the heat transfer through convection at the inside surfaces is crucial for the overall energy exchange of the cabin and the local solid temperatures. On the other hand, the accurate computation of the local convective heat transfer is computationally very expensive, because its direct dependence on the local flow field requires a corresponding resolution and therefore usually 3D CFD methods. In addition, transient weighting factors accounting for the distribution of the total energy change of the cabin air into the 12 zones are introduced. These, as well as the heat transfer coefficients (HTC) at the inside surfaces, are parameters directly influenced by the transient and spatially resolved flow field.

Therefore the focus in this work is set on the transient modeling of these parameters, namely the HTCs , the weighting factors and the average cabin air temperature . Models are derived from a limited number of predefined preliminary transient 3D CFD simulations for the investigated load case ‘Cooldown’, as depicted in Sect. 2.3.

Furthermore, a fast running reduced model is developed, derived from the reference 3D cabin model described in Sect. 2.1, which in combination with the beforementioned parameters as inputs allows the computation of the local transient temperatures for arbitrary transient scenarios. The method and structure of the reduced model is presented in [5] and shortly recapitulated in Sect. 2.2.

Validation of the computed transient local temperatures is performed for a transient test case based on the load case ‘Cooldown’ against the corresponding transient 3D CFD simulation, which has been conducted on the reference 3D model.

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