Parameterization and Transient Validation of a Variable Geometry Turbocharger for Mean-Value Modeling at Low and Medium Speed-Load Points

Abstract

The parameterization of variable geometry turbochargers for mean-value modeling is typically based on compressor and turbine flow and efficiency maps provided by the supplier. At low turbocharger speeds, and hence low airflows, the heat exchange via the turbocharger housing affects the temperature-based measurements of the efficiencies. Therefore, the lowspeed operating regime of the turbocharger is excluded from the supplied maps and mean-value models mainly rely on extrapolation into this region, which is regularly met in emission drive cycles, and hence of significance. This paper presents experimental data from a 2.0-liter turbocharged common-rail diesel engine. While the flow maps extend from the high-speed region in a natural way, the efficiency maps are severely affected by the heat transfer effect. It is argued that this effect should be included in the mean-value model. A physics-based parameterization is suggested for the turbine efficiency, which poses the biggest problems in turbocharger modeling. This new model structure is then validated with transient engine data.

Impact of the Heat Transfer on the Performance Calculations of Automotive Turbocharger Compressor

“…The geometrical turbocharger characteristics, mainly the distance between compressor and turbine, appear to influence greatly the heat fluxes. More recently, in 2002, Jung et al [6] suggest a parameterisation of turbine maps to obtain the behaviour of the turbine in its actual environment. They study heat losses considering the turbine as an exchanger which efficiency is derived from the manufacturers map.…”

Model-Based State Feedback Controller Design for a Turbocharged Diesel Engine with an EGR System

“…Usually the pressure drops across the coolers are neglected, and the temperatures after the coolers can be calculated by the following equations [16]:…”

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

“…When considering experimental results by [109,126,127] it is assumed that the turbine efficiency can be presented, with pressure ratio on the x-axis, by plotting curves for each speed line which goes through the point of maximum efficiency. The efficiency can be modelled as a parabolic function of the blade speed ratio [125,127,128,140]: From the above it is concluded that from a basic turbine map the turbine efficiency can be calculated as a function of pressure ratio and speed with the use of the blade speed ratio.…”