Search Results

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.

Under any driving conditions, the gas flow in present-day monoliths for automotive exhaust catalysts shows laminar characteristics resulting in thick boundary layers. These tend to restrict mass transfer, a highly desirable prerequisite to good catalytic activity. Based on the theory of catalysis and in the light of such all-important mass transfer, the design of the existing type of catalyst metal supports has been revised. The new metal supports vary from their predecessors by largely split and slotted honeycomb passages. In this way, gas flow is split and divided over and over again. This results in thin boundary layers and turbulence on the catalytically active support surfaces, with intense mass transfer between the core stream and the surface-contacting zone. The resultant improvements are discussed in terms of catalytic effect, size, weight, cost, internal flow, temperature equalization and component strength.

Since 1979, metal supports as pre-catalysts have been mass-produced and installed in export models of German automobiles bound for the United States and Japan. The close-to-engine installation directly behind the exhaust manifold places specialty high demands on the thermal and mechanical durability of the metal supports. Sueddeutsche Kuehlerfabrik Behr produces these metal supports under the name of “Metalit”. This paper covers the development, properties and special advantages of these metal supports. Encouraged by the successful use of hundreds of thousands of metal supports, a number of automobile manufacturers are working on programs to employ the Metalit concept for primary catalysts.