Abstract
Keywords - Cooling, absorption, lithium bromide, air-condensed, double stage.
Abstract - Nowadays automotive air conditioning is carried out by conventional mechanical vapour compression chillers. The compressor is driven directly by the IC engine. This diminishes the available mechanical energy for traction and additional fuel consumption must be afforded. Regarding environmental concerns, the use of these units implies an increasing of vehicle's carbon dioxide emissions. As open compressors are used there is a risk of refrigerant emissions. In modern automobiles the refrigerant usually utilised is the R134a or the R22. Both have a direct potential greenhouse effect of about 3500 times the one of carbon dioxide in a 20 year horizon. This is reduced to about 1500 times if this horizon is enlarged to 100 years.
In this article we present a theoretical study concerning an alternative AC system, today under development. It offers a reduction of the additional fuel consumption of 60% compared to the conventional mechanical compression AC machine, in addition with no reduction of the traction power. On the other hand, the environmental carbon dioxide impact is reduced by more than 60%. The system uses an absorption chiller fed by heat recovered from the engine cooling system. The cycle works with evaporation temperatures ranging from 5 to 8 ºC. The condenser and the absorber components work up to 60 ºC. The absorption and condensation heat rejection is transferred to the atmosphere by means of a forced air flow.
Taking into account that there are nowadays about 500 million vehicles in the planet, the replacement of conventional automotive mechanical vapour compression units with absorption chillers would have remarkable environmental benefits.