An experimental methodology and model for characterizing radial centrifugal compressors of turbocharged engines from diathermal perspective

Abstract

Since heat transfer represent an important role in turbochargers’ energy, and due to new technologies being implemented, it becomes necessary to develop new heat transfer models for new turbocharger configurations. The aim of the present work is to show how a compressor heat transfer model has been obtained. The correlation has been formulated in dimensionless numbers so it is not only valid for turbochargers but for other unshrouded radial compressor applications. On the one hand, the experimental work consists in a testing campaign that combines almost adiabatic and non-adiabatic tests. The turbocharger units employed have been an e-booster and a cooled-compressor-case turbocharger. Due to the use of cooling water in both, higher heat fluxes than those reported in previous literature have been measured. On the other hand a mathematical model has been developed taking into account the Nusselt correlation for the heat trans-fer that takes place in ducts. The correlation it is used for internal turbulent flow, in combination with Newton’s cooling law. To solve the heat transfer problem, a simplified system which includes some fitting terms has been proposed. The model has shown good agreement with the experimental data. The main applicability of this process remains in being able to predict accurately and in a relatively simple way, the heat transfer for radial unshrouded compressors. The previous implies the improvement in the prediction of compressor outlet temperature.