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In order to accurately predict the performance of a cooling module in an underhood environment, it is essential that the heat fluxes to the air from the various heat exchangers, such as radiator, condenser and charge air cooler, are modeled properly. Simulation models should therefore involve the prediction of the flow and temperature fields in both air and liquid side of heat exchangers. At Behr GmbH & Co., different simulation tools are successfully integrated in the development process to meet this goal. For underhood flow simulations, heat exchanger analysis programs are coupled directly with the flow solver. In order to verify the simulation a validation program has been set up based on the fact, that the air mass flow rate through the cooling module has a major influence on the performance of the radiator. Therefore, calculated air mass flow rates through the radiator were compared with the experimentally measured flow rates.

Laser welding is a joining process, which is comparatively new to industrial production and especially to heat exchanger manufacturing. Due to the high energy density of the laser beam, the process is characterized by faster welding speeds with deep penetration as compared to the conventional welding processes. Therefore laser welding technology is widely used in the automotive industry on a variety of different applications. This paper describes the application of laser welding as possible joining technology for exhaust gas heat exchangers made of stainless steel. The cooled exhaust gas recirculation (EGR) technology shows good potential for meeting the actual and future emission targets of diesel engines combined with acceptable fuel consumption. It will be shown that the selection of the base metal and the joining technology are extremely important for the durability of the product because of the severe operating environment the EGR cooler must endure.

In the USA truckers often spend the night in the driver's cab and use the engine during these rest periods to heat or cool the cab. This practice leads to environmentally detrimental pollutant and noise emissions as well as high fuel consumption. This prompted Behr GmbH & Co. to develop a device which eliminates these negative side-effects. Under normal driving conditions energy is extracted from the exhaust gas and stored in a zeolite reactor. When the vehicle is stationary for longer periods of time this stored energy can be used for cooling or heating the cab. In a variation of this system the exhaust gas heat exchanger is replaced by a fuel burner which is used to charge the zeolite reactor for the cooling process and which also serves as a direct source of heat for the cabin. Moreover, the materials used in the device are non-poisonous, ecologically compatible and recyclable.

Aluminum has a number of features which make it superior to the other non-ferrous metals (copper and brass) normally used for radiators in the past. Apart from the low specific weight, there are additional advantages, such as outstanding heat conductivity, strength, corrosion resistance and convenient forming and processing qualities. Brazed aluminum radiators with flat tubes and louvered serpentine fins are used for high horsepower engines and/or in confined spaces, while mechanically assembled round tube or oval tube radiators are preferred for smaller engines and/or where there is sufficient space. The excellent field results with car radiators have led to the use of aluminum radiators in trucks as well. More than 10 million fluxless brazed flat tube radiators with serpentine fins have been manufactured by Behr since 1975. Serial production for trucks was started in 1988.

This paper describes the use of computational fluid dynamics (CFD) as a tool to investigate fluid flow and heat transfer characteristics in louvered fin heat exchangers that are widely used in automotive industry. CFD supplies you with information from inside the heat exchanger like spatial distributions of temperature and velocity fields between the fins. The right interpretation of this information can reduce the number of prototypes and thus save time and money in the development process. Variations of grid density, differencing schemes and boundary conditions have been performed in 2D to ensure the reliability of the numerical results. With the recommendations of the 2-D study 3-D calculations have been made. The numerical results show good agreement with experimental data. The experimental values for overall pressure drop and heat transfer have been obtained using a test facility for heat exchangers at Behr.

Due to the introduction of new, more stringent exhaust gas emission regulations for diesel engines, expected to be enforced in Europe and the USA in 1999 and 2004, respectively, new emission-reducing technologies are becoming the focus of attention. One such technology is the cooled exhaust gas recirculation method (cooled EGR) which permits a reduction in emissions with only a small increase in fuel consumption. The heat exchanger used in such a system must be capable of meeting high demands in terms of compact design, performance, resistance to high temperatures, corrosion and fouling. The paper describes the development of an EGR cooler designed by Behr which meets these demands and, in particular, has a high performance density. This was achieved by using a new kind of heat exchanger core.

The Aluminum radiator has a number of features that make it very attractive for vehicle applications in general. Superior durability and reliability in conjunction with its excellent specific values for costs, performance and weight warrant a favorable solution for Heavy Duty Trucks. Behr has been supplying Aluminum radiators for trucks in Europe for over 10 years and in North America for 4 years. This paper examines the results based on this long-term experience. It reviews the field experience compared to Copper/Brass radiators, examines design and mounting features as well as the manufacturing processes. Durability, external and internal corrosion resistance are emphasized as essential characteristics. A special focus is the thermodynamics of Aluminum radiators. The paper reviews methods to simulate the thermodynamic behavior of radiators and the progress in the specific performance, based on the development of improved radiator core matrices.

A high efficiency lightweight heat exchanger has been developed for water jacket cooling of engine oil in heavy commercial vehicles. This heat exchanger is comprised of aluminum construction, and utilizes recent developments in heat exchanger technology to obtain high heat rejection, low parasitic loss, and superior strength. This new development offers significant advantages over today's stainless steel oil cooler technology. Specifically, a 15-20% increase in performance is typical, while a minimum of 50% weight savings is expected. This innovation has been released for high volume production, and represents a major benefit for our customers.