The Theoretical Calculation Of The New Unloading-pressure Energy Recycling System For Air-powered Engine

With the repaid development of modern industry, pollution and energy crisis are more and more serious. As oil and other fossil fuel resources are exhausted, the development of new energy is gaining much more attention. Although most automobile still use internal combustion engine, but apparently, new energy vehicles is the future of automobile industry. In our country, new energy auto focus mainly on hybrid cars, pure electric vehicles and fuel cell vehicles, study about other forms of new energy vehicles is relatively small. While in foreign countries, with compressed air as the power source of the pneumatic motor is arisen. This paper develops a series of calculation and discussion based on compressed air engine.Analyzed the structure, working process and energy distribution of normally used pneumatic engine, pointed out the reason why it has high energy density but low output--the loss of pressure unloading energy is too high, while the energy could be recycled. By calculating and analyzing the throttle valve--key parts of pneumatic engine decompressing process, found a very high proportion of the total energy, and recycling the energy can greatly improve the output of the whole system.For the energy loss problem, this paper proposes a new method of compressed air engine decompression system, put forward that replace the throttle valve by Pelton expander powered air-compressor to decompression, can simultaneously recover pressure unloading energy. Described the principle, structure, working process of this new system and the thermodynamic processes of compressed air working in detail.Calculated the operational capability of compressed air with the pressure of30MPa, the volume of300L, and the working pressure of IMPa while using the throttle valve and the new energy recovery system, found the maximum available energy increased from20.72MJ to32.17MJ, the efficiency improved from40.37%to62.67%, which isl.553times of the original. And the energy recovery efficiency, namely the theory efficiency while pressure releasing energy finally converted to kinetic energy, is81.9%. But in actual work, the total energy output improved from5.70MJ tol5.69MJ, the total system efficiency improved from11.10%to30.57%, enhanced nearly3times. Found from the calculation that additional working gas is provided by the new energy recycling system, which means the general mass of the mixed working gas is1.7times of the original; meanwhile the temperature increased from293K to376K, so that a part of the energy stored in compressed gas as thermal energy.Finally, discussed the influence of the pneumatic engine intake air temperature on the final output. Indicate through the calculation that in the course of practical work, the ascension of intake air temperature within a certain range can increase the output energy, but in consideration of the consumption heating gas, the efficiency rising is not very clear, and the operating cost to the pneumatic engine is unknown. So not using additional heating device but through other ways to heat the pneumatic engine inlet gas is a more advanced way in principle, and the new energy recycling system in this paper just meets this requirement.