Investigation of Maximum Temperature Rise on High Pressure Common Rail Injector Nozzle 2019-01-0276
In the multi-cycle working conditions, pressure at the front of the orifice of the common rail injector is very high, which is the injection pressure, while a low back pressure in the cylinder. The heat due to the large pressure difference during injection could raise the temperature of nozzle, and change the physical properties of the fuel in the orifice and the gas-liquid two-phase flow characteristics, finally directly affect the stability of the fuel injection quantity and injection rate, and ultimately influence the economics and emission of the diesel engine. Therefore, in this article, the PI400 Infrared Thermal Camera from DIAS of Germany was employed to test the temperature distribution of the injector nozzle at different common rail pressures and injection frequencies on a Bosch common rail injector. The results showed, with an increase in the injection pressure and injection frequency, the transient temperature and the final steady temperature at the nozzle of the injector increased. At different common rail pressures, the final temperature and the temperature increase rate of the injector nozzle was apparently different, and a higher common rail pressure could lead to a larger increase rate and a higher final temperature. At different injection frequencies, increase rates of the temperature and the final temperature of the injector nozzle are different, a higher injection frequency could lead to a larger temperature increase rate and a higher final temperature of the nozzle, however, the distinctions are not significant. At different injection frequencies and injection pressures, the temperature rise of the nozzle is more obvious at the first ten minutes of the injection, and then the temperature increase rate slows down. The temperature at the nozzle reaches a steady temperature at the later 30 minutes of the injection.