Experimental Study on the Combustion and Energy Flows of Vehicle Engine Under NEDC of Cold Start

Abstract

To enhance the fuel economy of a vehicle powered by a gasoline engine under road conditions, an energy flow test of a vehicle was performed experimentally under the New European Driving Cycle of cold start. The energy distributions and related influencing factors were analyzed using the test data. Results show that the effective power and thermal efficiency are mainly affected by the engine load except in the early stage of the New European Driving Cycle. Because of the retarded CA50 and longer CA10-90, the effective thermal efficiency is lower in the early phase of driving conditions. Initially, the heat transfer loss mainly comprises the loss of the heating, ventilation, and air conditioning system. The radiator then plays the major role, with its percentage affected by the engine load and decreasing under the extra-urban driving cycle. The exhaust gas loss is decided by the temperature and flow rate of the exhaust gas, while its percentage is mainly affected by the temperature of the exhaust gas. In the early phase of driving conditions, the retarded spark advance angle leads to a higher temperature of the exhaust gas and a greater exhaust gas loss. The pumping loss and its percentage are mainly determined by the engine speed under the urban driving cycle, and both decrease under the extra-urban driving cycle except at maximum vehicle speed.