Transient condition characteristics and parameter optimization of mine explosion-proof diesel engine

The existing explosion-proof diesel engine is transformed by adding explosion-proof flame arrester to the intake system and exhaust system of ground diesel engine. Coal mine underground conditions are complex, explosion-proof diesel engine is often in start-stop, acceleration and deceleration and other transient conditions. And the installation of explosion-proof flame arrester leads to serious obstruction of diesel intake and exhaust, aggravating the hysteresis of intake and exhaust system under transient conditions, and seriously deteriorating the transient conditions characteristics. In order to solve this problem, the steady-state simulation model of explosion-proof diesel engine is established by GT-POWER, and the transient condition control model of explosion-proof diesel engine is established by Simulink, and the transient simulation model of explosion-proof diesel engine is formed by coupling the transient condition control model with the steady-state simulation model. Based on the transient simulation model of explosion-proof diesel engine, the dynamic performance of explosion-proof diesel engine under two typical transient conditions of constant speed and variable torque and constant torque and variable speed is simulated and analyzed. The results show that under the transient condition of constant speed and variable torque, compared with the diesel engine before the explosion-proof transformation, the air-fuel ratio of the explosion-proof diesel engine decreases faster, the maximum burst pressure in the cylinder decreases, and the torque hysteresis is more obvious. Moreover, the faster torque rises, the more serious the hysteresis effect. Under the transient condition of constant torque and variable speed, the air-fuel ratio of explosion-proof diesel engine decreases with the increase of speed, but the process of increasing speed with small load has little effect on the air-fuel ratio. In order to optimize the parameters of explosion-proof diesel engine, the effects of injection advance angle and the number of flame arrester barriers on the power and emission performance of explosion-proof diesel engine are analyzed by simulation. The results show that the maximum burst pressure, maximum combustion temperature, friction torque and power in the cylinder all increase with the increase of the injection advance angle, the volume fraction of CO and HC decreases with the increase of the injection advance angle, and the volume fraction of NO_x increases with the increase of the injection advance angle. With the increase in the number of intake and exhaust explosion-proof flame arrester fences, the maximum burst pressure in the cylinder of the explosion-proof diesel engine increases and the maximum combustion temperature decreases. The increase of the number of intake and exhaust explosion-proof flame arrester fences has a negligible effect on the friction torque and power of the explosion-proof diesel engine, but it can inhibit the exhaust emission concentration to a certain extent. Properly increasing the fuel injection advance angle and the number of intake and exhaust explosion-proof flame arrester fences can improve the transient condition characteristics of explosion-proof diesel engines to a certain extent.