Investigation on a Computer Controlled Sequential Turbocharging System for Medium Speed Diesel Engines

An investigation on the sequential turbocharging (ST) of a Kelvin TFSC6 medium speed diesel engine developing 320 kW at 1200 r/min is reported in this paper. The sequential turbocharging (ST) system, utilising turbochargers of unequal size, resulted in significant improvement when compared with previously designed systems. The engine test results show that the new ST system improves the engine performance at both high and low speeds except, at or near to, the ‘transfer’ speed. The engine low speed performance is improved with fuel saving of up to 7 g/kwh for the 1st sequence. However, the improvement of the high engine speed performance at the 2nd sequence was limited by some boost air leakage from a flexible connecting pipe from the peak unit compressor outlet to the intercooler inlet. An optimised sequence transfer control mode is also proposed in this research. Two control valves designed for this ST system, one at the peak unit turbine inlet and the other at the compressor outlet, work very well during the engine test period