• Energy Research

AbstractDue to increasing global greenhouse gas emissions there is urgency to pursue all measures to develop carbon‐neutral energy technologies. The most attractive approach for large‐scale energy storage is perhaps in the form of synthetic fuels. In this work, a nitrogen‐based fuel consisting of an aqueous solution of urea and ammonium nitrate is evaluated for chemical stability and handling safety. The steady combustion of the fuel was demonstrated at 10 MPa. Thermal analysis under an ambient pressure dry air flow in the range of 25–500 °C showed that the monofuel does not react with atmospheric oxygen in a ventilated open system, and only endothermic thermal processes were observed in the condensed phase. Under applied pressure the fuel combusts exothermically above 300 °C, after water vaporization. The fuel described herein is an excellent gas generator with a potential effluent composition of 73.0 % H2O, 21.6 % N2, and 5.4 % CO2, which is an environmentally friendly working fluid.

AbstractDue to increasing global greenhouse gas emissions there is urgency to pursue all measures to develop carbon‐neutral energy technologies. The most attractive approach for large‐scale energy storage is perhaps in the form of synthetic fuels. In this work, a nitrogen‐based fuel consisting of an aqueous solution of urea and ammonium nitrate is evaluated for chemical stability and handling safety. The steady combustion of the fuel was demonstrated at 10 MPa. Thermal analysis under an ambient pressure dry air flow in the range of 25–500 °C showed that the monofuel does not react with atmospheric oxygen in a ventilated open system, and only endothermic thermal processes were observed in the condensed phase. Under applied pressure the fuel combusts exothermically above 300 °C, after water vaporization. The fuel described herein is an excellent gas generator with a potential effluent composition of 73.0 % H2O, 21.6 % N2, and 5.4 % CO2, which is an environmentally friendly working fluid.

AbstractReview: 90 refs.

AbstractReview: 90 refs.

AbstractWe describe and review recent research of a low‐carbon nitrogen‐based alternative fuel consisting of an aqueous solution of urea and ammonium nitrate (UAN). This fuel possesses a volumetric energy density of 4.44 MJ L−1. Conceptually, it is intriguing to think of ample atmospheric nitrogen as a future storage hub for sustainable and economic hydrogen derived from water rather than fossil fuels. First, we discuss and compare the nitrogen‐ and carbon‐based routes for chemical hydrogen storage. Second, we review recent research developments of this fuel: continuous combustion with lower NOx emissions than US regulation, computerized combustion simulations, ambient and high pressure thermal analyses, safety and stability considerations, catalytic effect on the effluent, and metal corrosion resistance at reaction and storage conditions. Aqueous UAN is found to yield about 99.9 % N2 when combusted at 25 MPa without a catalyst. Finally, future prospects and research needs are discussed.

AbstractWe describe and review recent research of a low‐carbon nitrogen‐based alternative fuel consisting of an aqueous solution of urea and ammonium nitrate (UAN). This fuel possesses a volumetric energy density of 4.44 MJ L−1. Conceptually, it is intriguing to think of ample atmospheric nitrogen as a future storage hub for sustainable and economic hydrogen derived from water rather than fossil fuels. First, we discuss and compare the nitrogen‐ and carbon‐based routes for chemical hydrogen storage. Second, we review recent research developments of this fuel: continuous combustion with lower NOx emissions than US regulation, computerized combustion simulations, ambient and high pressure thermal analyses, safety and stability considerations, catalytic effect on the effluent, and metal corrosion resistance at reaction and storage conditions. Aqueous UAN is found to yield about 99.9 % N2 when combusted at 25 MPa without a catalyst. Finally, future prospects and research needs are discussed.

Abstract The mutual oxidation of n-pentane and NO2 at 500–1000 K has been studied at equivalence ratios of 0.5 and 1.33 by using an atmospheric-pressure jet stirred reactor (JSR). N-pentane, O2, NO, NO2, CO, CO2, CH2O, C2H4, and CH3CHO are simultaneously quantified, in-situ by using an electron-impact molecular beam mass spectrometer (EI-MBMS), a micro-gas chromatograph (μ-GC), and a mid-IR dual-modulation faraday rotation spectrometer (DM-FRS). Both fuel lean and rich experiments show that, in 550–650 K, NO2 addition inhibits low temperature oxidation. With an increase of temperature to the negative temperature coefficient (NTC) region (650–750 K), NO2 addition weakens the NTC behavior. In 750–1000 K, high temperature oxidation is accelerated with NO2 addition and shifted to lower temperature. Two kinetic models, a newly developed RMG n-pentane/NOx model and Zhao's n-pentane/NOx model (Zhao et al., 2018, Submitted) were validated against experimental data. Both models were able to capture the temperature-dependent NO2 sensitization characteristics successfully. The results show that although NO2 addition in n-pentane has similar effects to NO at many conditions due to fast NO and NO2 interconversion at higher temperature, it affects low temperature oxidation somewhat differently. When NO2/NO interconversion is slow, NO2 is relatively inert while NO can strongly promote or inhibit oxidation.