SIMULATION OF HEAT TRANSFER PROCESSES IN TURBOCHARGERS

Abstract

This thesis work deals with the simulation of heat processes in a turbocharger using SIMULINK. A simplified model is designed which takes the turbine inlet conditions and the mechanical power absorbed by the compressor as input from the experimental data and gives the transient variation of the turbine exhaust temperature as the output. Subsequently an advanced model is designed which takes the turbine pressure ratio and inlet temperature and the compressor inlet conditions as input from the experimental data and gives the transient variation of the turbine exhaust temperature, turbine casing temperature, bearing housing temperature and the compressor outlet temperature as the output. The correlations for the turbine total efficiency and the effective turbine throat areas as a function of the turbine pressure ratio are developed by performing dynamic experiments on the turbocharger test cell. The models are then validated by conducting experiments on the turbocharger test cell under forced and natural convection conditions with three different VTG positions (100%, 50%and 0%). The simplified model gives a very close approximation of the turbine exhaust temperature under natural convection. The advanced model gives a close approximation of the transient variation of the bearing housing temperature and the compressor outlet temperature. The model works well with different VTG positions but the accuracy is decreased with 0%VTG position. The results show an over prediction of the turbine total efficiency and under prediction of the outside heat transfer coefficient under forced convection.