Experiment investigation on the performance and regulation rule of two-stage turbocharged diesel engine for various altitudes operation

Abstract

To satisfy intake demand under high-altitude condition, two-stage turbocharging system is matched for diesel engine. However, it is necessary to regulate turbocharging system at low altitude due to decline of overall system efficiency. Moreover, regulation rule of turbocharging system, in terms of regulation ability and overall efficiency, which is critical to engine performance and unclear for various altitudes operation so that regulation strategy of turbocharging system depends on numerous calibration. In this paper, regulation rules at various altitudes are investigated by experiments. Test result indicates regulation ability increases as altitudes rises up and provides less excess air coefficient with constant regulation area. Whereas, overall efficiency presents disparate tends at different altitude. Output torque and fuel consumption continue to deteriorate as the bypass valve opens at high altitude condition, while can be improved below 2000 m with reasonable regulation area due to greater overall efficiency. The effect of altitude on regulation area boundary and scope are acquired. Finally, optimal regulation strategy at various altitudes is proposed. Experiment results manifest the maximal increment of overall system efficiency achieves 7.3% and leads to fuel consumption reduction of 13.9 g/kW h under 2200r/min and 0 m condition, compared to fixed turbocharging system.