Cooling system improvements - assessing the effects on emissions and fuel economy

The work reported in this paper details an experimental study of the effects of cooling system hardware changes on diesel engine emissions and fuel economy. Experiments were performed under both steady state and transient conditions and complemented by statistical assessments. Techniques for assessing the thermal integrity of the engine as a consequence of such changes are also presented. An experimental design was constructed to investigate the effect of water pump throttling, coolant flow control through the oil cooler, and the adoption of a pressure resistive thermostat (PRT). Use of these thermal controls offers a useful trade-off between NO_x and fuel economy, with a saving of around 3 per cent in b.s.f.c. for a 10 per cent NO_x penalty at low load, where NO_x output is less of a concern. However, these benefits were not observed during drive cycle testing