Maximum turbocharger efficiency for an engine operating at 50% brake thermal efficiency

With the announcement of a reduction in CO2 emissions by 15% by 2025 and a further planned 15% reduction by 2030 in Europe, commercial vehicle manufacturers have become increasingly focused on reducing fuel consumption by improving overall engine efficiency. As a result, commercial vehicle manufacturers are turning more towards optimising the internal combustion engine, focussing on highly efficient air handling systems, in which the turbocharger plays a key role. This paper will aim to show how a well matched, optimised turbocharger can impact the engines Brake Thermal Efficiency (BTE). Carefully matching and optimising the turbocharger enables an increase in both open cycle and closed cycle efficiency which are key factors for engine performance. When combined, the optimisation of the turbocharger compressor, turbine and bearing system along with thermal energy management allow for increased overall turbocharger performance which is required to achieve high levels of BTE.