Ammonia for power

A review of ammonia as a compression ignition engine fuel

This paper evaluates the potential of hydrogen (H-2) and ammonia (NH3) as carbon-free fuels The combustion characteristics and NOx formation in the combustion of H-2 and NH3 at different air-fuel equivalence ratios and initial H-2 concentrations in the fuel gas were experimentally studied NH3 burning velocity improved because of increased amounts of H-2 atom in flame with the addition of H-2 NH3 burning velocity could be moderately improved and could be applied to the commercial gas engine together with H-2 as fuels H-2 has an accelerant role in H-2-NH3-air combustion, whereas NH3 has a major effect on the maximum burning velocity of H-2-NH3-air In addition, fuel-NOx has a dominant role and thermal-NOx has a negligible role in H-2-NH3-air combustion Thermal-NOx decreases in H-2-NH3-air combustion compared with pure H-2-air combustion NOx concentration reaches its maximum at stoichiometric combustion Furthermore, H-2 is detected at an air-fuel equivalence ratio of 100 for the decomposition of NH3 in flame Hence, the stoichiometric combustion of H-2 and NH3 should be carefully considered in the practical utilization of H-2 and NH3 as fuels H-2 as fuel for improving burning performance with moderate burning velocity and NOx emission enables the utilization of H-2 and NH3 as promising fuels Copyright (C) 2014 John Wiley & Sons, Ltd

Study on using hydrogen and ammonia as fuels: Combustion characteristics and NOx formation

This review focuses on the use of renewable ammonia for power generation applications and discusses options to convert industrial-grade generators to run on ammonia fuel. The different methods to produce clean ammonia are also discussed in terms of possible advantages and challenges from socio-economic, energetic and environmental perspectives. The main aim of using clean fuel sources, such as ammonia and hydrogen, is to achieve higher sustainability and low carbon emissions compared to conventional fuels. In addition, the present review comparatively assesses and discusses methods for clean ammonia synthesis based on their technical, economic and environmental performance criteria. Numerous potential strategies to improve the clean ammonia production methods are also explored, namely, liquid-electrolyte based systems, composite-membrane based systems, solid-state electrolyte, ceramic/inorganic proton-conducting solid electrolyte based systems, polymer-membrane based systems, O2 conducting-membrane based systems, and molten salt based electrochemical systems. Furthermore, some potential methods to convert various types of commercially available generators to be able to ammonia are proposed and discussed based on the experimental work carried out in the field.

A review on clean ammonia as a potential fuel for power generators

https://hal.archives-ouvertes.fr/hal-02498694/document

Experimental study on ammonia/hydrogen/air combustion in spark ignition engine conditions

Performance characteristics of a compression-ignition engine using direct-injection ammonia–DME mixtures

Highway Fuel Economy Testing of an RCCI Series Hybrid Vehicle

Investigation of Steady-State RCCI Operation in a Light-Duty Multi-Cylinder Engine Using “Dieseline”

Reactivity Controlled Compression Ignition (RCCI) combustion in a light-duty multi-cylinder engine over transient operating conditions using fast response exhaust UHC1, NO and PM measurement instruments was investigated. RCCI has demonstrated improvements in efficiency along with low NOx and PM emissions by utilizing in-cylinder fuel blending, generally using two fuels with different reactivity in order to optimize stratification. In the present work, a “single-fuel” approach for RCCI combustion using port-injected gasoline and direct-injected gasoline mixed with a small amount of the cetane improver 2-ethylhexyl nitrate (EHN) was studied with custom designed, compression ratio of 13.75:1, pistons under transient conditions. The EHN volume percentage in the mixture for the direct-injected fuel was set at 3%. In an experimental investigation, comparisons were made to transient RCCI combustion operation with gasoline/diesel. The experiments were performed over a step load change from 1 to 4 bar brake mean effective pressure (BMEP) at constant 1,500 rev/min on a General Motors Z19DTH 1.9 liter diesel engine The transients were conducted by changing the accelerator pedal command to provide a desired torque output with a DRIVVEN engine control unit (ECU) that replaced the original Bosch ECU. All relevant engine parameters are adjusted accordingly, based on 2D-tables. Previous to the transient engine operation, 4 steady-state points were used to obtain performance and emission values. Engine calibration at these 4 points, as well as the interpolation of the intermediate points, allowed for smooth operation during the instantaneous step changes. Differences between the steady-state and transient results indicate the complexity of transient operation and show the need for additional controls to minimize undesirable effects. The steady-state points were calibrated by modifying the fuel injection strategy (actual Start of Injection (aSOI) timing, port-fuel injection (PFI) fraction, etc.), EGR and rail pressure in order to obtain predefined values for the crank angle at 50% of total heat release (CA50). Furthermore, emission targets (HC1 < 1500ppmC3, NO < 10ppm, FSN < 0.1 with a maximum pressure rise rate < 10bar/deg) and noise level targets (<95dB) for RCCI combustion were maintained during the calibration and mapping. The tests were performed with a closed-loop (CL) calibration by using a next-cycle (NC) controller to adjust the PFI ratio of each cycle in order to reach the steady-state CA50 values in the table. The results show that single-fuel RCCI operation can be achieved, but requires significant alteration of the operating conditions, and NOx emissions were significantly elevated for gasoline/gasoline-EHN operation. While combustion phasing could not be matched, UHC1 emissions were at a similar level as for gasoline/diesel combustion. It is expected that the implementation of different injection strategies and boosted operation, combined with use of higher compression ratio pistons in order to compensate for the lower reactivity direct injection (DI) fuel, could raise the potential for improved performance.Copyright © 2015 by ASME

Transient “Single-Fuel” RCCI Operation With Customized Pistons in a Light Duty Multi-Cylinder Engine


 Current concepts for fast rotorcraft and tiltrotor-/tiltwing aircraft require a speed variation in a wide range; this wide range cannot be covered by varying only the turbine speed. Such new aircraft under development require a rotor system with a large rotor speed variation but constant turbine speed which leads to the consequence that a transmission with a variable ratio during flight is necessary. TU Munich, TU Wien and Zoerkler gears work in the funded research projects VARI-SPEED and VARI-SPEED II on a solution "constant turbine speed / variable rotor speed" that consists of a transmission with variable ratio and a rotor system with rotor head and rotor blades for variable rotor speed. The helicopter UH-60A from Sikorsky Aircraft is used as reference. 

The project VARI-SPEED showed the feasibility of a rotor system with variable speed. In the current project VARISPEED II the dynamic simulation of the system is built up. The paper describes the approach to the simulation and shows first results for each component. After completion of the simulation the elaborated rotor control will be implemented in a flight simulator for evaluation by pilots. 


Christopher W. Gross

Papers

Performance characteristics of a compression-ignition engine using direct-injection ammonia–DME mixtures

Highway Fuel Economy Testing of an RCCI Series Hybrid Vehicle

Investigation of Steady-State RCCI Operation in a Light-Duty Multi-Cylinder Engine Using “Dieseline”

Transient “Single-Fuel” RCCI Operation With Customized Pistons in a Light Duty Multi-Cylinder Engine

Dynamic Simulation of a Rotor System with Variable Speed