In accordance with at least on aspect of this disclosure, there is provided a hydrogen fuel system for aircraft. The hydrogen fuel system includes a gas turbine engine and a fuel feed conduit. The fuel feed conduit is defined at least in part by, in fluid series, a liquid hydrogen tank fluidly connected to a combustor of the gas turbine engine, a liquid hydrogen pump to drive fuel to the combustor of the gas turbine engine, an evaporator, and an electric heat source in thermal communication with the evaporator to add heat into a flow of hydrogen passing through the evaporator. In embodiments, the electric energy source associated with the electric heat source to power the electric heat source.

An engine system includes: an ammonia engine; a reforming device that has a reforming catalyst for cracking ammonia gas into hydrogen and configured to reform ammonia gas to generate reformed gas containing hydrogen; and a control unit. The control unit includes: a purge controller configured to control a reforming injector so as to be closed and control a reforming throttle valve so as to be opened, after an ignition switch gives an instruction of a stop of the ammonia engine; and an engine stop controller configured to control main injectors so as to be closed, after the ignition switch gives the instruction of the stop of the ammonia engine.

An internal combustion engine and a method of controlling an internal combustion engine are provided, that are more efficient than existing engines. The internal combustion engine includes a combustion chamber, and the engine is configurable to operate in: a compressionless operating mode where the engine is driven by combustion of fuel and oxidant in the combustion chamber without compression of the fuel and oxidant; and a compression generating operating mode where the engine is used to compress fluid in the combustion chamber.

An emission-free power generation system includes a combustion chamber having a first inlet for receiving a fuel and a closed-loop fluidic circuit fluidly connected between a second inlet of the combustion chamber and an outlet of the combustion chamber. Combustion gases from the combustion chamber include only water and carbon dioxide, and the fuel includes performic acid or a combination of formic acid and hydrogen peroxide.

A natural gas engine is utilized for fracturing. The natural gas engine can utilize recovered natural gas as the fuel source. This eliminates the need for expensive diesel fuel. The natural gas system results in several benefits including economic savings as well as environmental advantages in the reduction of particulate, greenhouse gases, including NOx, methane, CO2, CO, VOC etc.

A natural gas engine is utilized for fracturing. The natural gas engine can utilize recovered natural gas as the fuel source. This eliminates the need for expensive diesel fuel. The natural gas system results in several benefits including economic savings as well as environmental advantages in the reduction of particulate, greenhouse gases, including NOx, methane, CO2, CO, VOC etc.

An internal combustion engine for use with hydrogen fuel, the engine having at least one cylinder assembly which includes a combustion chamber having a cylinder, a cylinder head and a reciprocating piston assembly, the cylinder defining a cylinder longitudinal axis; a fuel injector for injecting fuel into the combustion chamber, the fuel injector defining an injector longitudinal axis; and a fuel flow director, wherein the fuel flow director is located in the fuel flow path between an outlet of the fuel injector and the combustion chamber. The fuel injector is oriented such that the injector longitudinal axis extends at a first angle; and the fuel flow director is configured to direct fuel flow into the combustion chamber at a second angle, different to the first angle.

A two-stroke cycle uniflow-scavenged opposed-piston engine is configured to use hydrogen fuel. The opposed-piston engine has at least one cylinder and a pair of pistons disposed for opposed motion in a bore of the cylinder. Hydrogen fuel is injected into the cylinder early in a compression stroke of the opposed-piston engine, and is ignited in a combustion chamber formed between the pistons late in the compression stroke.

A two-stroke cycle uniflow-scavenged opposed-piston engine is configured to use hydrogen fuel. The opposed-piston engine has at least one cylinder and a pair of pistons disposed for opposed motion in a bore of the cylinder. Hydrogen fuel is injected into the cylinder early in a compression stroke of the opposed-piston engine, and is ignited in a combustion chamber formed between the pistons late in the compression stroke.

An internal combustion engine includes a four-stroke combustion cylinder assembly configured for combustion of hydrogen gas within at least one combustion chamber of the combustion cylinder assembly such as to drive a crankshaft of the engine, an intake passage upstream of the cylinder assembly and an exhaust passage downstream of the cylinder assembly; a displacement compressor arranged within the intake passage, the displacement compressor being configured for compression of intake gas, an exhaust gas recirculation system configured for recirculating at least a portion of the exhaust from the exhaust passage to the displacement compressor.