Experiments and Modeling of Dual-Fuel HCCI and PCCI Combustion Using In-Cylinder Fuel Blending

Low-temperature combustion (LTC) strategies, such as HCCI (Homogeneous Charge Compression Ignition), PCCI (Premixed Charge Compression Ignition), and RCCI (Reactivity Controlled Compression Ignition), have been developed to effectively reduce NOx and PM while increasing the thermal efficiency of diesel engines. Through numerical analysis, this study examined the effects of the injection timing and two-stage injection ratio of diesel fuel, a highly reactive fuel, on the performance and exhaust gas of RCCI engines using gasoline as the low reactive fuel and diesel as the highly reactive fuel. In the case of two-stage injection, combustion slows down if the first injection timing is too advanced. The combustion temperature decreases, resulting in lower combustion performance and an increase in HC and CO. The injection timing of approximately -60°ATDC is considered the optimal injection timing considering the combustion performance, exhaust gas, and maximum pressure rise rate. When the second injection timing was changed during the two-stage injection, considering the combustion performance, exhaust gas, and the maximum pressure increase rate, it was judged to be optimal around -30°ATDC. In the case of two-stage injection, the optimal result was obtained when the first injection amount was set to approximately 60%. Finally, a two-stage injection rather than a single injection was considered more effective on the combustion performance and exhaust gas.

Numerical Study on the Effect of Diesel Injection Parameters on Combustion and Emission Characteristics in RCCI Engine

It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If theperformance is poor, engine will be damaged by overheating. But, the development timing of engine is faster thantiming of vehicle, it is difficult to test the cooling performance of new engine and vehicle. In this study the powertaincooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted.From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertraincooling performance was estimated. Key Words : Coolant Flow Data, Heat Rejection Rate, PTC (Powertrain Cooling Performance) * Corresponding Author : Sunki Min(Ajou Motor College)Tel: +82-10-9072-2658 email: skmin@motor.ac.krReceived January 29, 2015 Accepted May 7, 2015Revised (1st March 20, 2015, 2nd May 6, 2015)Published May 31, 2015

Estimation of PTC (Powertrain Cooling) Performance with Heat Rejection Rate

When turbochargers are applied to engines, the temperature of the engine becomes high, making the cooling of pistons very important. To solve this problem, an oil jet is used. The oil jet provides oil to the underside of piston for cooling. When an oil jet is used, oil pump size-up and oil cooler are needed because of the increased oil flow rate and higher oil temperature. On the other hand, these increase the friction torque of the engine. This study examined how much the friction torque of an engine increases by an oil jet, oil cooler, and oil pump size-up. In addition, the proportions of the friction torque of the engine increased by each part were measured by changing the engine assembly condition. At low speed, the oil pump and oil cooler had a larger effect on the friction torque than the other factors. At high speed, oil cooler had a larger effect than the other factors.

Sunki Min

Papers

Numerical Study on the Effect of Diesel Injection Parameters on Combustion and Emission Characteristics in RCCI Engine

Estimation of PTC (Powertrain Cooling) Performance with Heat Rejection Rate

Study of Engine Oil Jet System Effect on Engine Friction

A Study of Improving Combustion Stability with Sonic Wave Radiation