Analysis of carbon reduction contribution of Ball Bearing(BB) turbocharger in heavy duty diesel engines

To elucidating the contribution of BB to carbon and emission reduction in heavy-duty diesel engines, turbocharger efficiency, full load, Design Of Experiments (DOE) of lowest fuel consumption point, and responsiveness test were conducted under back-to-back test conditions. The test results show that BB could increase turbo side efficiency, showcasing a maximum improvement of 10.58% in the realm of low expansion ratios. For the full load test, the improvement of BB on Brake Specific Fuel Consumption (BSFC) at low speeds is significantly higher than that at high speeds. The most significant improvement is at 800 rpm, where BSFC is reduced by 1.39 g/kW·h with BB compared to the condition without BB. Under different peak cylinder pressures, the BB can reduce BSFC by about 0.5 g/kWh. For DOE of lowest fuel consumption point, under varying peak cylinder pressures, BB can reduce BSFC by approximately 0.5 g/kW·h. With higher peak cylinder pressures, the reduction in BSFC tends to diminish. The effect of BB on Nitrogen Oxides (NOx) and soot emissions can be neglected. For responsiveness test, after 900 rpm, the response time with BB condition is slightly lower than that without BB condition, with an overall difference of 0.2-0.3 seconds.