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

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. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Kyung-Wook Choi received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 2006. He is now working on a doctoral degree in Hanyang University. Kyung-Wook’s research interests include Hybrid Electric Vehicle, Internal Engine Combustion, and Engine Cooling System. Ki-bum Kim was awarded a bachelor’s degree in naval architecture and ocean engineering from Chung-Nam National University in the Republic of Korea. In August 2001, he began graduate study at the University of Florida. Kibum graduated with a Master of Science degree in mechanical engineering from the University of Florida in August 2003. He went on to earn his Ph.D. in mechanical engineering, also at the University of Florida, in August 2006. He is working as a research professor at Hanyang University. Ki-Hyung Lee is a Professor at the department of mechanical engineering in Hanyang University. He received his B.S and M.S degree in Hanyang University in 1983 and 1986. Then he graduated with a Ph.D. degree in mechanical Engineering at Kobe University, Japan in 1989. He worked as a research engineer at Nissan motor’s central technical center for 4 years.