Potentials of an Axial Turbine Turbocharger to improve the Lean-Burn Operating Range of an Internal Combustion Engine (el. knyga) (skaityta knyga) | knygos.lt

Aprašymas

This thesis deals with the development of an exhaust gas turbocharger (T/C) that enables lean-burn in the range of the WLTC. The remaining engine map is covered with lambda=1. For this purpose, a single-stage T/C with a shrouded axial turbine in combination with a variable nozzle compressor (VNC) is designed and manufactured as a prototype and then validated on the Engine Test Bench (ETB). The geometric design of the turbine is carried out using CFD simulations at the TFD, LUH. As basis for this, requirements are determined in the 0D/1D simulation based on a 1.5 l 3-cylinder SI-DI gasoline engine. After the manufacturing of the prototype, it is tested on the ETB at lambda=1 and lean-burn operation. For lean-burn operation, a H2 injection system is implemented to the stock engine. This enables lambda=2 up to 2,000 rpm, which is gradually lowered to 1.5 up to 4,500 rpm. The reason for this is the limitation of the H2 fraction to 3.8 vol-% of the intake air. The experimentally investigated engine-T/C system is then transferred back into the simulation for further analyses. The outcome of this thesis is firstly to prove that an axial turbine can be realised for the use in a passenger car engine and can successfully be tested on the ETB. At lambda=2, the specific, brake effective Nitrogen Oxide (NOX)-raw emissions are reduced to values around 0.2 g/kWh without exhaust gas aftertreatment (<100 ppm). Due to project-related restrictions, the full efficiency potential of the axial turbine T/C prototype is reduced. However, further simulations with the validated models show that the developed turbine has the potential to fulfil the set requirements (eta_TC=49%). The required load of BMEP=14 bar can almost (13.7 bar) be achieved in lambda=2 operation from 1,500 rpm.