Investigation of emission characteristics affected by new cooling system in a diesel engine

Abstract

In a typical cooling system of automotive engine, a mechanical water pump is used to control the flow rate of coolant. However, this traditional cooling system is not suitable for a high efficiency performance in terms of fuel economy and exhaust emission. Therefore, it is necessary to develop a new technology for engine cooling systems. These days, the electronic water pump is spotlighted as the new cooling system of an engine. The new cooling system can provide more flexible control of the coolant flow rate and the engine temperature, which used to be strongly relied on the engine driving conditions such as load and speed. In this study, an engine experiment was carried out on a New European Drive Cycle (NEDC) with a 2.7L diesel engine. The electric water pump operated by BLDC motor and the electronic valve were installed in the cooling system to control the coolant flow rate and temperature. This paper explains that the exhaust emissions were reduced with an increase in the engine temperature and a decrease in the coolant flow. From this experiment, we found that increasing coolant temperature had a significant effect on reducing the emissions (e.g. THC and CO). Decreasing coolant flow also affected the reduction of emissions. In contrast, NOx emission was observed to increase in these conditions.