Development of Two Stage Turbo-Charging for Medium Duty Diesel Engine of Power Generation Application 2012-28-0007
Two stage turbo charging provides a suitable method to achieve a significant increase of the boost level, as well as a wider operating range for a diesel engine. This paper describes detailed and easily applicable method for two stage turbocharger matching for constant speed engine, in view of finding an optimal combination of turbochargers - low and high pressure ones. It also describes technique that can be used for optimizing solution with better fuel consumption and boosting together with satisfying of all given constraints such as maximum before turbine and compressor out temperatures, maximum turbocharger speed, peak cylinder pressures and smoke limit. This paper presents evaluation of potential for two stage turbocharger for power generation application by simulation and then experimental results. A 4 cylinder, 4.32 L inline water cooled, turbocharged intercooled diesel engine has been taken as a base engine (93 kW @ 1500 rpm), and the aim is to up rate this engine to develop 147.2 kW power i.e. up rate by 58%. The boost system architecture investigated consists of two turbochargers in series with one intercooler after each compressor. The use of 1D thermodynamic simulation tool helped in deciding the suitability of two-stage turbo-charging for the engine and in reducing the number of actual experimental efforts, resulting into fast development. Based on the theoretical calculations and simulation results actual experiments were carried out and results were then compared with the calculated and simulated values. Engine test results showed a good match with the theoretical calculations and simulations. Engine developed the target power, fulfilled the emission norms and limits of maximum cylinder pressure, maximum before turbine temperature and compressor out temperature, AFR requirement etc. This work showed that two-stage turbo-charging is a potential technology that can be used to achieve higher specific power output from the engine combined with NOx reduction and improving fuel economy of the engine.