Research On The Using Method Of Exhaust Cooling Energy Of Pneumatic Engine

As a new-typed engine, pneumatic engine received a lot of attention in recent years. But it was found through analysis of its energy balance that, a portion of energy was wasted in its exhaust air. In this paper, the characteristics of pneumatic engine cooling capacity were investigated to explore its recycling pathway and two kinds of cooling energy recycling solutions were proposed.Based on the model of pneumatic engine working process which was established, by simulation under different conditions aerodynamic characteristics of the engine exhaust parameters, the pneumatic engine exhaust cooling capacity and power under different conditions were calculated, and the model was verified by experiments. Analysis of changing rules of exhaust temperature and gas flow under different engine speed and different inlet pressure was researched. Moreover, cooling capacity in different conditions was calculated. The two technical schemes put forward in this paper is to use exhaust gas to cool automobile passenger compartment and to cool the radiator in the internal combustion engine cooling system. Cooling results were investigated and feasibility analysis were carried out respectively.The important researches and conclusions studied in the paper are as follows:Firstly, it was calculated by the simulation method that at certain engine speed, when the inlet air pressure increased, the exhaust temperature dropped gradually with the inlet air pressure increasing, while the exhaust flow and exhaust cooling air capacity went up under the same condition; on the other hand, under certain inlet air pressure, the exhaust air temperature, the air flowing and the cooling capacity went up linearly with the increasing of engine speed.Secondly, the heat load was linearly correlated with the temperature inside the car; the cold exhaust air was applied to decrease the inside car temperature, at the certain pneumatic engine speed, air temperature inside the vehicle gradually dropped with the increasing inlet pressure; at certain inlet air pressure, the temperature inside the vehicle dropped with the increasing of the engine speed. To cool the vehicle inside down to25℃, the air extraction ratio decreased against the increasing inlet air pressure at certain engine speed; the exhaust rate decreased gradually against the increase of engine speed under certain inlet pressure, and the extraction ratio ranged from18%to90%.At last, it was found that, under certain air inlet pressure, as engine speed increased, the outlet water temperature dropping trend was akin to linearity, the cooling system heat transfer increasing trend was akin to linearity, and the needed cooling air exaction ratio decreased gradually; under certain engine speed, as inlet pressure increased, the outlet cooling water temperature of radiator dropped gradually, the cooling system heat transfer gradually increased, and the needed cooling air exaction ratio decreased gradually.