Waste Heat Recovery Applied to a Tractor Engine

Abstract

Due to the environmental impact of pollution, the depletion and increasing price of fossil fuel resources, current research focuses on reducing vehicle fuel consumption. The modern agricultural sector is highly dependent on petrol, as no exploitation can work without tractors or agricultural machinery. One solution to reduce the dependence on petrol is to install waste heat recovery systems on engine exhaust gases. Tractors are good candidates for waste heat recovery since they are used at high load over long periods, which are ideal operating conditions for waste heat recovery systems. Several technologies can be used to achieve this aim, such as an external heat engine, thermoelectricity or thermoacoustics. The present study considers the external heat engine, in particular the Rankine-Hirn cycle which is a phase change fluid engine. This well-proven technology is the one most widely used in industry to recover lost heat. Different heat loss recovery techniques are presented in this paper, in which we detail our model of the Rankine-Hirn engine used to dimension our future test bench. We focus on the selection of fluid, pressure and temperature as a function of the hot source temperature. Lastly, we present an initial evaluation of the increase in efficiency depending on the variation in the heat source.