Possibilities of Ammonia as Both Fuel and NOx Reductant in Marine Engines: A Numerical Study

Nowadays, the environmental impact of shipping constitutes an important challenge. In order to achieve climate neutrality as soon as possible, an important priority consists of progressing on the decarbonization of marine fuels. Free-carbon fuels, used as single fuel or in a dual-fuel mode, are gaining special interest for marine engines. A dual fuel ammonia-diesel operation is proposed in which ammonia is introduced with the intake air. According to this, the present work analyzes the possibilities of ammonia in marine diesel engines. Several ammonia-diesel proportions were analyzed, and it was found that when the proportion of ammonia is increased, important reductions of carbon dioxide, carbon monoxide, and unburnt hydrocarbons are obtained, but at the expense of increments of oxides of nitrogen (NOx), which are only low when too small or too large proportions of ammonia are employed. In order to reduce NOx too, a second ammonia injection along the expansion stroke is proposed. This measure leads to important NOx reductions.

Development of a Generic Dual Fuel ECU for Common Rail Diesel Engine Control

<p>Rising costs of diesel fuel has led to an increased interest in dual fuel diesel engine conversion, which can offset diesel consumption though the simultaneous combustion of a secondary gaseous fuel. This system offers benefits both environmentally and financially in an increasingly energy-conscious society. Dual fuel engine conversions have previously been fitted to mechanical injection systems, requiring physical modification of the fuel pump. The aim of this work is to develop a novel electronic dual fuel control system that may be installed on any modern diesel engine using common rail fuel injection with solenoid injector valves, eliminating the need for mechanical modification of the diesel fuel system. The dual fuel electronic control unit developed replaces up to 90 percent of the diesel fuel required with cleaner-burning and cheaper compressed natural gas, providing the same power output with lower greenhouse gas emissions than pure diesel. The dual fuel system developed controls the flow of diesel, gas, air, and engine timing to ensure combustion is optimised to maintain a specific torque at a given speed and demand. During controlled experimental analysis, the dual fuel system exceeded the target substitution rate of 90 precent, with a peak diesel substitution achieved of 97 percent, whilst maintaining the same torque performance of the engine under diesel operation.</p>

Development of a Generic Dual Fuel ECU for Common Rail Diesel Engine Control

<p>Rising costs of diesel fuel has led to an increased interest in dual fuel diesel engine conversion, which can offset diesel consumption though the simultaneous combustion of a secondary gaseous fuel. This system offers benefits both environmentally and financially in an increasingly energy-conscious society. Dual fuel engine conversions have previously been fitted to mechanical injection systems, requiring physical modification of the fuel pump. The aim of this work is to develop a novel electronic dual fuel control system that may be installed on any modern diesel engine using common rail fuel injection with solenoid injector valves, eliminating the need for mechanical modification of the diesel fuel system. The dual fuel electronic control unit developed replaces up to 90 percent of the diesel fuel required with cleaner-burning and cheaper compressed natural gas, providing the same power output with lower greenhouse gas emissions than pure diesel. The dual fuel system developed controls the flow of diesel, gas, air, and engine timing to ensure combustion is optimised to maintain a specific torque at a given speed and demand. During controlled experimental analysis, the dual fuel system exceeded the target substitution rate of 90 precent, with a peak diesel substitution achieved of 97 percent, whilst maintaining the same torque performance of the engine under diesel operation.</p>

Methodological basis for the conversion of transport diesel engines of transport diesel engines to gas-diesel operation

The expediency of the search, development and use of alternative environmentally friendly motor fuels is scientifically substantiated, the main of which is the use of gas fuel, which is much more efficient than diesel fuel in terms of overall environmental safety. The relevance of the research carried out and the developments proposed in this article will make it possible to realize the fundamental complex advantages of the ecological and operational nature of the use of the gas-diesel cycle of the ICE operation. This is in line with the Paris Protocol on a climate to reduce greenhouse gas emissions to keep the global average temperature rising. The paper describes the main features and methods of converting diesel engines to their compressed natural gas power supply. The advantages and disadvantages of all methods of implementing the gas-diesel cycle on existing diesel installations of low and high power are analyzed in detail. The main operations and changes in operating parameters for each method of implementing the gas-diesel cycle on operating diesel engines are also described. The use of a mixed quantitative and qualitative control of the supply of compressed gas and diesel fuel for various loads of a diesel engine operating on a gas-diesel cycle has been scientifically substantiated. The systematization is carried out and the comparative characteristics of liquid and gas motor fuels, which can be used for the implementation of the gas-diesel cycle in diesel engines, are presented in tabular form, general conclusions are described.

Analysis of operating characteristics of 7S50MC diesel engine under direct air management

The paper provides a theoretical analysis of the operational performance of a marine two-stroke diesel engine in a wide range of modes, operating on a helical characteristic. Reducing the diesel load causes a decrease in the coefficient of excess air for combustion, which is characteristic of two-stroke diesel engines with a relatively high boost pressure. To control the air flow rate, it is proposed to use an adjustable nozzle apparatus as part of a turbine of a turbocharger unit. Changing the angle of the blades of an adjustable nozzle apparatus by turning them, an impact was made on the characteristics of the turbine, compressor and, accordingly, on the operational performance of the diesel engine. With decreasing the angle of the blades of the nozzle apparatus, the effective passage area of the turbine of the turbo-charging unit decreases. This causes an increase in gas pressure in front of the turbine and, consequently, an increase in the power of the turbine and compressor. This increases the boost pressure and the available work of the air charge of the cylinder. The engine operates with a large excess air ratio for combustion and increased efficiency. There are presented the results of a comparative analysis of diesel performance caused by rotation of the blades of an adjustable nozzle apparatus and the initial version, in which the angle of the blades of the nozzle apparatus remained unchanged. The angle of rotation of the blades was selected in such a way as to ensure unchanged the coefficient of excess air for combustion in all the studied diesel operation modes. The studies showed a considerable improvement in the performance of a two-stroke diesel engine at shared load modes when using an adjustable nozzle apparatus of a turbo-charging unit.