Experimental analysis of pulse detonation engine fuelled by biogas mixtures

Abstract

The demand on energy conversion system with high efficiency has led researchers to study the technology of Pulse Detonation Engine (PDE). Among the prominent features of PDE are enhanced thermodynamic efficiency, high thrust generation, reduced design complexity, and lightweight. The main focus of this study is to develop a Pulse Detonation Engine with the ability of running on biogas fuel and operating at the minimum frequency of 10Hz. First, the combustion characteristics of biogas in detonation mode is calculated using NASA Computer program of Chemical Equilibrium with Applications (CEA) with two different oxidizing agents: air and oxygen. The equivalence ratio was varied from 0.7 to 1.4 with 0.1 increments. It was found that the increased methane concentration significantly improved performance in terms of pressure, temperature and Mach number of detonation characteristics. Next, an experiment was carried out to assess the effects of hydrogen addition in biogas on detonation characteristics performance. A single detonation tube and fuel with composition of 60% methane and 40% C 02 was used for the experiment. It was found that the optimal amount of hydrogen addition into the biogas fuel mixture is 15%. For this fuel composition, the detonation pressure is improved by 23%. Finally, the experiment is conducted at a frequency of 10 Hz. At this operating condition, the pressure of 9.87 bar and 20% addition of hydrogen has been identified to provide the most optimal PDE performance. It was found that the detonation characteristics of biogas are affected by the percentage of methane concentration in biogas. C 02 dilution is identified to have reduced the flame speed, temperature, and pressure of biogas.