Development of a Cost Effective Power Train Cooling System for a Passenger Car with Rear Engine

The present automobile era in India is driven by development of small size and low cost ‘value for money’ cars. Proper utilization of space and low cost engineering of the vehicle aggregates plays a key role for attaining the goal of low cost-small cars. This paper illustrates the development of power train cooling system of such cost sensitive passenger car with rear engine and rear mounted heat exchangers.

The major obstacle for the power train cooling system of rear engine-rear mounted heat exchanger (radiator) is absence of ram air effect at higher vehicle speeds and air temperatures higher then ambient, as observed for front mounted heat exchanger. The subject vehicle encountered power train cooling system failure at max speed operating condition and the project timeline required a quick solution without any major modifications and cost escalation.

In case of subject vehicle because of its packaging, the air flow rate for heat exchanger was fully dependent of fan capacity. However, at higher vehicle speeds there was an opportunity to boost the air flow rate by proper air management within vehicle boundaries. After DOE and CFD analysis, an air deflector was introduced at the bottom of heat exchanger which improved the heat transfer rate by utilizing the high velocity air underneath the vehicle.