Search Results

In the last few years, the effect of diabatic test conditions on compressor performance maps has been widely investigated leading some Authors to propose different correction models. The aim of the paper is to investigate the effect of heat transfer phenomena on the experimental definition of turbocharger maps, focusing on turbine performance. An experimental investigation on a small turbocharger for automotive application has been carried out and presented. The study focused onto the effects of internal heat transfer on turbine thermomechanical efficiency. The experimental campaign was developed considering the effect of different heat transfer state by varying turbine inlet temperature, oil and coolant temperature and compressor inlet pressure. An original model previously developed by the Authors is adopted for the correction of compressor steady flow maps.

The flow in turbocharger compressors and turbines for automotive engine application is highly unsteady in nature, as it responds to the intake and exhaust manifolds of the internal combustion engine. The optimization of the turbocharger system is therefore a very difficult task, since only steady flow maps are generally provided by turbocharger manufacturer. For several years a specialized components test facility operates at the University of Genoa, particularly suitable to test turbochargers under steady and unsteady flow conditions. The test bench has been continuously upgraded in order to study components under pulsating flow condition by using different layout configurations. A recent set-up makes it possible to study turbocharger compressor under unsteady flow condition by using a rotating valve pulse generator system. Measurements of pressure signals downstream the compressor, instantaneous mass flow rate and turbocharger rotational speed are performed.

The paper presents the main results of a study focused on the definition of exhaust emission factors for a waste collection vehicles fleet, taking into account the specific mission profiles. As a first step, on the basis of the fleet characteristics, different classification criteria were applied, aiming at the identification of suitable vehicle classes. Then, the calculation of the exhaust emissions for each class was based on a two terms equation, the first related to the vehicle travel (considering different sources for the relevant emission factors) and the second to the equipment use, whose contribution is estimated on the basis of different parameters. A computational code was then set up for the evaluation of the daily emission of normalized pollutants for the whole fleet and each required service.