Alternative fuels are essential to enable the transition to a sustainable and environmentally friendly energy supply. Synthetic fuels derived from renewable energies can act as energy storage media, thus mitigating the effects of fossil fuels on environment and health. Their economic viability, environmental impact, and compatibility with current infrastructure and technologies are fuel and power source specific. Nitrogen-based fuels pose one possible synthetic fuel pathway. In this review, we discuss the progress and current research on utilization of nitrogen-based fuels in power applications, covering the complete fuel cycle. We cover the production, distribution, and storage of nitrogen-based fuels. We assess much of the existing literature on the reactions involved in the ammonia to nitrogen atom pathway in nitrogen-based fuel combustion. Furthermore, we discuss nitrogen-based fuel applications ranging from combustion engines to gas turbines, as well as their exploitation by suggested end-uses. Thereby, we evaluate the potential opportunities and challenges of expanding the role of nitrogen-based molecules in the energy sector, outlining their use as energy carriers in relevant fields.

Progress and Prospective of Nitrogen-Based Alternative Fuels.

Hydrazine monopropellant has been used in thrusters for maneuvering satellites and landing spacecraft. Testing and handling procedures for hydrazine monopropellant thrusters are complicated, because of the toxicity of the hydrazine and its decomposition product gases. Therefore, simulated numerical analysis can help elucidate the effects of various thruster design parameters and can reduce both development time and expenses. In this study, a simulated numerical analysis was performed in which the catalyst bed was modeled as a one-dimensional porous medium. The resulting physical phenomena were examined by considering variations in catalyst bed characteristics incurred by catalyst pellet failure. From observations of various hot-firing experiments, it was determined that the upper region of the decomposition chamber was preferentially damaged in failure situations, which led to the conclusion that catalyst failure occurs in the upper region only. We simulated various cases based on the crushing and mass lo...

Effects of Catalyst Bed Failure on Thermochemical Phenomena for a Hydrazine Monopropellant Thruster Using Ir/Al2O3 Catalysts

A general theoretical model is presented to analyze the steady-state decomposition process of liquid monopropellants in packed beds for thruster systems. Additionally, an experiment studying the decomposition of liquid hydrazine in a packed bed is used to validate this model. The liquid droplet evaporation rate is determined through calculating the gas-liquid mass transfer for the mixture temperatures lower than the liquid propellant boiling point and solving the gas-liquid or liquid-solid heat transfer equations at the temperature exceeding the boiling point. The process of liquid propellant decomposition in packed beds are simulated based on the Naive-Stokes equation for the mixture model integrated with the developed liquid evaporation rate, in which both the heterogeneous catalytic reaction coupled with the diffusion of reactants in the pore of catalyst, and the homogenous decomposition reactions are considered. The calculated results for the axial distribution of the temperature are in good agreement with the experimental data. (c) 2014 American Institute of Chemical Engineers AIChE J, 61: 1064-1080, 2015

Steady-State Behavior of Liquid Fuel Hydrazine Decomposition in Packed Bed

A ground hot-fire test and numerical simulations were conducted to analyze the high-temperature gas flow in a monopropellant hydrazine thruster used for the reaction control of small satellites. A 5N grade thrusterwas used for these tests and simulations. The ground hot-fire test results show the basic characteristics of a hydrazine thruster and were used as verification criteria for the numerical analysis. It was found that the fraction of ammonia dissociation is an essential variable for determining the thruster performance based on a one-dimensional isentropic analysis. A relatively simple relation between the catalyst bed temperature and the fraction of ammonia dissociation adopted in the simulation showed that it reduces the analysis error from an arbitrary assumption of the fraction of ammonia dissociation without solving the complicated hydrazine catalytic reaction. The thruster performance was effectively predicted by numerical analysis, which includes the effect of fraction of ammonia dissociation. The significant features of the analysis program are that solving the complicated hydrazine decomposition process can be avoided and that two-dimensional flowfield information in the thruster can be provided covering a wide range of propellant inlet pressures from 3.45 to 24.14 bar.

K. Anantha Ram

Papers

Prediction of the concentration of hydrazine decomposition products along a granular catalytic bed

Experimental investigations of the 10 N catalytic hydrazine thruster

Mathematical modelling of the unified bipropellant propulsion system