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La Verrière, France

Buisson M.,Ecole Centrale Lyon | Ferrand P.,Ecole Centrale Lyon | Soulat L.,Ecole Centrale Lyon | Aubert S.,Fluorem SAS | And 3 more authors.
Computers and Fluids | Year: 2013

Optimal design techniques recently gained a wide popularity in the industry as relatively powerful computers have become broadly available and as attractive tools such as surrogate models and evolutionary optimization went through maturation. However, when dealing with complex geometries and difficult physical phenomena to be modeled, computing costs still remain high, due to the large number of required numerical simulations feeding the traditional surrogate models. Turb'Opty© is a meta-model which only requires a single CFD simulation at a reference configuration point, based on automatic differentiation of the discretized Reynolds-Averaged Navier-Stokes equations and high-order Taylor-series expansions. A flow database containing the derivatives of the physical variables with respect to the design variables is produced by this parameterization tool and thoroughly explored, in the post-processing step, by a multi-parameter and multi-objective genetic algorithm coupled to the associated extrapolation tool. In this paper, post-processing of the derivative database will be depicted through a 3D study of an automotive shrouded fan with casing treatment. © 2012 Elsevier Ltd.

Saab S.,Valeo Thermal Systems | Hetet J.-F.,Ecole Centrale Nantes | Maiboom A.,Ecole Centrale Nantes | Charbonnelle F.,Valeo Thermal Systems
SAE Technical Papers | Year: 2013

The impact of the drag coefficient of a vehicle on its fuel consumption is very important. This paper will treat a proposition to reduce the drag coefficient via a reduction of the underhood opening area. The coastdown technique is adopted to find the drag coefficient. Three post-processing methods are then compared. Although, reducing the underhood opening ameliorates the drag coefficient, it influences as well the thermal performance of the cooling system, causing a possible overheating of the engine. For this reason, the impact of the underhood opening area on the cooling air speed is studied in detail as well. The purpose of these tests is to draw some variation laws that govern the response of a vehicle to a reduction in the underhood opening. Copyright © 2013 SAE International.

Saab S.,Valeo Thermal Systems | Hetet J.-F.,Ecole Centrale Nantes | Maiboom A.,Ecole Centrale Nantes | Charbonnelle F.,Valeo Thermal Systems
SAE Technical Papers | Year: 2013

The tightening restrictions, in terms of fuel consumption, have pushed the vehicle manufacturers and equipment suppliers into searching for innovative ways to reduce the carbon dioxide emissions. Along with the ameliorations added to the engine itself, additional systems are grafted to the engine in order to keep up with the ever-changing laws. Isolating the impact on the fuel consumption of an added system, by on board testing, is a complicated task. In this case, using simulation modeling allows the reduction of delays related to prototyping and testing. This paper presents modeling of various thermal systems in a vehicle and their interactions to evaluate the fuel consumption using AMESim software. As means to reduce the CPU cost of the model (calculation time), without decreasing its predictability, engine modeling has been done by two steps: high frequency model and mean value model. While the first model is used to characterize the engine indicated work, exhaust losses and thermal losses, the second model is integrated in a complete vehicle model where the additional thermal systems are connected. From these additional systems, the model contains: the cooling system, lubricating system, EGR (Exhaust Gas Recirculation) and charged air cooling system. Using this model helps evaluating the cost of each system in terms of fuel consumption. Comparing different cooling systems architectures is possible. Furthermore, the impact of air shutters on both the aerodynamics and the thermal stability of the engine is studied. Copyright © 2013 SAE International.

Saab S.,Valeo Thermal Systems | Charbonnelle F.,Valeo Thermal Systems | Hetet J.-F.,Ecole Centrale Nantes | Maiboom A.,Ecole Centrale Nantes
Proceedings of the 26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013 | Year: 2013

The international laws aim more and more to reduce the carbon dioxide emissions, especially in the ground transportation field. To keep up with these constantly restraining regulations, the automotive industry searches to better understand the impact of each subsystem in the vehicle on the global fuel consumption. Nevertheless, until now, almost no studies have been done on the impact of the cooling system performances and its design on the fuel consumption of an internal combustion engine. This paper aims to present a new approach for a complete vehicle modeling while taking into consideration the major interactions between the cooling system and its surroundings. Thus, along with the engine and the cooling system, the air admission system (charged air cooler and exhaust gas recirculation cooler), the lubricating system, the thermal inertias and the electric components are modeled. In order to have highly predictive and accurate results while keeping a reasonable calculation time, the engine model used is developed in two steps: starting with a high frequency engine model, various operating points are calculated. Then, using these results, a mean value engine model (MVEM) is built. This second model uses the concept of efficiencies maps to find the operating point, heat dissipation and fuel consumption. The results given by the model are compared to tests done on a vehicle with a similar engine displacement. The comparison is even made in transient motion. Such model will help comparing, energy wise, different cooling system architectures for a traditional vehicle. The next step will be using this model for hybrid electric vehicles and study the possibilities of energy recuperation for the cabin thermal management.

Lissner M.,Valeo Thermal Systems | Lissner M.,IRSTEA | Tissot J.,Valeo Thermal Systems | Leducq D.,IRSTEA | And 2 more authors.
Applied Thermal Engineering | Year: 2016

This study focuses on the optimization of a phase change heat accumulator used in engine cooling loop of automotive applications. Heat transfer is mainly limited by the low PCM heat transfer rate, due to a relatively low thermal diffusivity. A significant conductivity enhancement can be achieved by adding fins, but this also leads to decrease the heat storage capacity of the accumulator by reducing the volume available for phase change materials. Thus, geometry characteristics of fins such as pitch, height and thickness play an important role in the performance and storage capacity of the heat accumulator and should be considered carefully. In order to optimize these geometric parameters, a numerical model is developed to simulate various configuration of heat accumulator. The simulation results are presented and used to define a set of optimal solutions based on heat transfer rate and heat storage capacity. The model can be easily applied to similar geometries, materials or applications. Results show that there is an optimal height of fins that provides a satisfying heat transfer rate. On the other hand, pitch and thickness of fins should be the smallest as possible to improve contact points between fins and wall and to improve temperature homogeneity. However, results show that optimal design of fins depends on flow conditions and, several optimal may be defined considering heat accumulator application. © 2016 Elsevier Ltd. All rights reserved.

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