Análise termodinâmica e reprojeto de um motor a vapor

Abstract

In 1712, Thomas Newcomen developed an atmospheric, low energy-efficient steam engine, which was enhanced by James Watt in 1769, which improved efficiency by separating the piston from the condenser engine. Currently, the most efficient engines are those that have expansion cycles in different cylinders, making the most of the expansive power of steam. The capacity of electricity generation depends on how it is designed, both geometrically and thermodynamically, and can provide power in the range of 75 kW to 5 MW, and the Rankine cycle is the most found in thermal power generation plants. This work aims to perform a thermodynamic analysis in a steam engine, and consequently to improve some mechanical components, making use of both traditional methods of calculations, as well as computerized simulations. The steam engine to be studied has a low thermal efficiency in addition to high vapor consumption, while not being able to maintain stable power at high speeds. After verifying the discrepancy between the calculation method using the P-V diagram and the simulation, an analysis of the current situation of the prototype by simulation is carried out, at the same time as some components are improved, aiming at increasing efficiency, the geometric and working limits of the engine. It was then obtained the reduction of steam consumption in approximately 17,4% and the efficiency increased by 43,9%. Even after the decrease in the exhaustion time in 18,5%, and due to the complexity in changing the time of admission, the consumption remained high, leading to change the nominal work rotation.