Inner-Insulated Turbocharger Technology to Reduce Emissions and Fuel Consumption from Modern Engines

Abstract

Reducing emissions from light duty vehicles is critical to meet current and future air quality targets. With more focus on real world emissions from light-duty vehicles, the interactions between engine and exhaust gas aftertreatment are critical. For modern engines, most emissions are generated during the warm-up phase following a cold start. For Diesel engines this is exaggerated due to colder exhaust temperatures and larger aftertreatment systems. The De-NOx aftertreatment can be particularly problematic. Engine manufacturers are required to take measures to address these temperature issues which often result in higher fuel consumption (retarding combustion, increasing engine load or reducing the Diesel air-fuel ratio).In this paper we consider an inner-insulated turbocharger as an alternative, passive technology which aims to reduce the exhaust heat losses between the engine and the aftertreatment. Firstly, the concept and design of the inner-insulated turbocharger is presented. A transient 3D CFD/FEM (Computation Fluid Dynamics/ Finite Element Modelling) simulation is conducted and predicts that external heat losses will be reduced by 70% compared to a standard turbocharger, i.e. non-insulated turbocharger. A 1D modelling methodology is then presented for capturing the behaviour of the inner-insulated turbocharger. This is important as conventional models based on isentropic efficiency maps cannot accurately predict turbine outlet temperature. The alternative model is essential to demonstrate benefits in system-level simulations. Experimental results are presented from a transient air-path testing facility to validate the 1D model and demonstrate the characteristics of the inner-insulated turbocharger. Finally, the validated 1D model is used within a powertrain optimization simulation to demonstrate an improvement in fuel consumption for iso-NOx emissions over a low load city cycle of up to 3%.The work was conducted under the THOMSON project which has received funding from the European Union's Horizon 2020 Program for research, technological development and demonstration under Agreement no. 724037. The project aims to increase the market penetration of 48V hybrid vehicles.

Hybrid Powertrain Technology Assessment through an Integrated Simulation Approach

“…A thermally insulated turbocharger was another technology developed through the THOMSON project by BorgWarner. The design of the turbocharger and the development of a bespoke heat transfer model are described separately [4]. The heat transfer model was integrated into the toolchain presented in this paper and optimisation studies were performed to predict the drive-cycle fuel reductions through using this technology.…”

Analytical study on a turbine housing with inner insulation structure for rapid catalyst light-off

“…Therefore, some examples of inner insulation structures in a turbine housing of turbochargers were proposed. Burke et al [2] designed the inner-insulated turbocharger based on ISOLITE Turbo-Liner [3] with the use of FEA combined with CFD. Gas stand tests were conducted to validate the 1D model for the inner-insulated turbocharger, in which the improvement in fuel consumption under RDE (Real Driving Emission) cycle was confirmed.…”

“…Gas stand tests were conducted to validate the 1D model for the inner-insulated turbocharger, in which the improvement in fuel consumption under RDE (Real Driving Emission) cycle was confirmed. Following reference [2], Liu et al [4] examined thermal performance of the inner-insulated and the standard turbochargers in engine tests. Slight improvement in turbine outlet temperature was observed under various operating conditions.…”

Effect of adding ceramic thermal barrier coating on the turbocharger efficiency, external and internal heat transfer

“…However, with the ceramic coating, it reduce the heat through turbine wall [13]. An insulated turbocharger with silicate insulation material can reduced heat flux by 5% to 70% compared to standard turbocharger and improved the fuel consumption by 3% [14]. Ceramic material will also tremendously reduce the surrounding high temperature, thus will protect material of the surrounding components such as cables, rubber materials and piping.…”