External heat losses in small turbochargers: Model and experiments

•Energy losses by heat transfer in turbochargers can be very important.•External losses from hot turbine can be the most representative.•A simplified model of the external losses in the turbocharger is presented.•The model has been adjusted against experimental measurements on a turbocharger test cell.•The validation has been performed on engine test cell.

The behavior of small turbochargers is deeply affected by heat transfer phenomena. The external heat losses of these machines are studied and a simplified model that takes into account both radiation and convective mechanisms has been proposed. The model has been adjusted in a turbocharger test bench for two different turbochargers, later on it has been validated against experimental measurements on an engine test bench. Finally, the model has been used to estimate the most important external heat flows among the different elements of the turbocharger, showing the operative points in which external heat transfer in turbochargers cannot be neglected.