Performance of a Heavy-Duty Turbocharged Diesel Engine Under the Effect of Air Injection at Intake Manifold During Transient Operations

The effectiveness of an air injection technique for the improvement in transient response of heavy-duty turbocharged diesel engines has been investigated but only to a limited extent. In the present work, the investigations are performed to improve the response characteristic of a heavy-duty turbocharged diesel engine under the transient event of rapid acceleration at low engine speeds. The engine model is developed using Ricardo wave software; and after the validation with the data obtained from the real engine, wave model is used to investigate the effectiveness of an air injection system for the improvement in performance of turbocharged diesel engine. The effect of air injection is observed by varying the air injection pressure and the time of acceleration. The turbocharger’s response parameters such as the compressor exit pressure, turbine inlet temperature and turbine inlet pressure have been monitored to quantify the turbocharger lag. A pressure value of 1 bar is found to be the optimum injection pressure value that significantly reduces the turbocharger lag corresponding to all the selected parameters. Furthermore, faster recovery time is observed for the tests with 1 s duration of acceleration than that with 2 s duration of acceleration. Turbo lag reduction in percentage per unit energy is found to be 29.0%, 39.2% and 55.5% per Joule based on compressor exit pressure, turbine inlet pressure and turbine inlet temperature, respectively, at 1 bar of air injection pressure.