Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Thermodynamic Modelling of Rotating Detonation Engines Cycles
Submission Author:
Robson Eduardo dos Anjos Schneider , RS , Brazil
Co-Authors:
Robson Eduardo dos Anjos Schneider, Cesar Celis, Andrés Armando Mendiburu Zevallos
Presenter: Robson Eduardo dos Anjos Schneider
doi://10.26678/ABCM.ENCIT2022.CIT22-0104
Abstract
A rotating detonation engine (RDE) is a type of engine where the reactants are fed into the combustor and the detonation waves travels around the circumference of the combustor with supersonic speed, performing work through pressure gain combustion. Rotating detonation engines can be applied to power-generating devices, such as a gas-turbine, or to give propulsion to vehicles, like aircrafts. Studies have claimed that, with a rotating detonation engine, it is possible to achieve a decrease of 9% in fuel consumption compared to traditional gas-turbine engines, an increase of up to 15% in the total pressure in the combustor due to detonation, an increase of 5% in thermal efficiency (considering a gas-turbine setting), an increase in thermal efficiency of 4.6% (with just the combustor) and up to 14% increase in power plant efficiency over conventional J class turbines. Such attributes make the rotating detonation engine an attractive choice to improve the efficiency of gas-turbines in general. On the other hand, the high energy density and the near-stoichiometric operation of the RDE makes the device's thermodynamic analysis complex. Equivalence ratios close to the stoichiometric proportion also results in exhaustion products of high temperature that need to be diluted with efficiency. The high variation of pressure on a rotating detonation engine can cause structural failure on the components of the engine, since they work near the mechanical limit, and, also, it can have consequences on the turbine’s efficiency, as shock waves and flow separation may be prejudicial. Such factors, among others, means that rotating detonation engines are still in an experimental stage of development and are not mass-produced. Thus, this work aims to perform a thermodynamic comparison of the thermal efficiency of gas turbines operating with a combustion chamber and a detonation chamber, considering different fuels, such as methane, ethanol and hydrogen. For that, a thermodynamic model was developed, where the composition of the gases is determined by the minimization of the Gibbs free energy and the temperature, pressure and speed of detonation are determined by the Chapman-Jouguet theory. The present work explores the influence of parameters such as compression ratio, fuel composition and equivalence ratio in the thermal efficiency generated.
Keywords
Rotating Detonation Engine, Thermal Efficiency, thermodynamic model
