Análise comparativa do desempenho de turbocompressores veiculares com câmara de combustão tubular na microgeração de energia

Abstract

This master's work presents the development of a work that has the objective of evaluating the composition of vehicular turbochargers for microgeneration of energy and to develop a tubular combustion chamber model to equip gas microturbines derived from turbochargers. In the development of the work, using the software Cycle-Tempo, it is made the evaluation of possible configurations of gas micro turbines derived from turbochargers, with respect to the number of axes and devices of increasing thermal efficiency (intercoolers, heat recover e reheater). In total, ten different configurations were simulated, and the analyzes were done directly in the thermal efficiency parameters of the sets, evaluating the relation between the energy contributed by the fuel and the energy delivered in a hypothetical electric generator. Turbochargers are then defined to form a particular gas micro turbine configuration and, being used the turbocharger performance maps from a manufacturer. From the operating parameters of the equipment, a three-dimensional combustion chamber model was developed in CAD software. The model went through five stages of simulations in Computational Fluid Dynamics (CFD). The first three steps served to develop and improve the three-dimensional model of combustion chamber and, due to software limitations, did not involve combustion. Using operational contour conditions, the velocity profile along the combustion chamber, the pressure loss, the turbulence intensity, the homogenization between the air and fuel reactants and the division of the mass flow in each section of the combustion chamber were evaluated. From the three-dimensional model was developed a prototype of the combustion chamber, built from commercial PVC pipes. The prototype was evaluated experimentally with air flow at room temperature using the coupling in series between a centrifugal fan and a blower. In the experiment the air mass flow division in each section of the combustion chamber and the loss of pressure were evaluated. The CFD simulations were redone in the fourth stage, where the boundary conditions were the parameters of mass flow, pressure and temperature, obtained experimentally. Thus, a direct comparison between the results obtained experimentally and the results of CFD simulations can be made. At the end of the work the fifth step was performed, where a heat source was inserted simulating the energy input of the combustion, allowing the temperature evaluation in the combustion chamber. The CFD simulations indicated results similar to those predicted in the literature, regarding the division of mass flow, pressure loss and velocity distribution. However, the experimental evaluations presented high measurement uncertainty for the mass flow division. Regarding pressure loss, the experimental method proved to be adequate.