Various methods and systems are provided for controlling emissions and a likelihood of engine knock during combustion in a multi-fuel engine. A method for an engine includes mixing an amount of a first fuel and an amount of a second fuel to combust a fuel mixture having a fuel ratio of the first fuel relative to the second fuel, the first fuel having a faster combustion flame speed relative to the second fuel, the fuel mixture having an air-to-fuel ratio with an amount of air delivered to the engine. The method further includes controlling either or both of a speed of combustion and a stability of combustion of the fuel mixture with the amount of air delivered to the engine by changing at least one of the fuel ratio, the air-to-fuel ratio, or both of the fuel ratio and the air-to-fuel ratio.

A drawdown compressor assembly for recovering natural gas from a gas line includes a first tubing configured for connection to a first pipe of the gas line at a one end of the first tubing. A compressor is attached to an opposite end of the first tubing and configured to draw natural gas from the first pipe through the first tubing and into the compressor for being compressed by the compressor. A second tubing is connected to the compressor at one end of the second tubing and configured for connection to a second pipe of the gas line at an opposite end of the second tubing. Activation of the compressor draws the natural gas from the first pipe through the first tubing and delivers compressed natural gas to the second pipe through the second tubing.

An engine system includes an engine configured to combust liquid natural gas and generate an exhaust gas comprising methane; a catalytic reactor coupled downstream of the engine and configured to convert methane into a product through one or more of oxidative coupling of methane (OCM) reaction and steam methane reforming (SMR) reaction; and a recirculation loop configured to recirculate at least a part of the product back to the engine.

A separation chamber type anti-surge valve may include a valve body formed with a charge air passage inlet and a charge air passage outlet, and a valve cover coupled to the valve body by a fastening member to define an empty inner space between the valve body and the valve cover, in which the inner space is divided into a diaphragm chamber and a bypass chamber by a valve guide, one side tip of a valve rod being fixed in the diaphragm chamber, a valve disc fixed to another side tip of the valve rod, and the diaphragm chamber is divided into a control pressure chamber and a normal static pressure chamber.

An air/fuel mixture is ignited in an internal combustion engine by receiving the air/fuel mixture as an incoming air/fuel mixture flow from a main combustion chamber of the internal combustion engine into an enclosure adjacent the main combustion chamber. The enclosure defines a first chamber enclosing first and second ignition bodies and the enclosure defines a second chamber adjacent the first chamber and connected to the first chamber via a passage. A portion of the air/fuel mixture received in the enclosure is directed toward an ignition gap between the first and second ignition bodies and another portion is directed into the second chamber. The air/fuel mixture is then ignited in the ignition gap, and flame from combustion in the first chamber is ejected into the main combustion chamber. Then, flame from combustion in the second chamber is ejected into the main combustion chamber.

A hydraulic fracturing system for fracturing a subterranean formation is disclosed. In an embodiment, the system can include a plurality of electric pumps fluidly connected to a well associated with the subterranean formation and powered by at least one electric motor, and configured to pump fluid into a wellbore associated with the well at a high pressure; at least one generator electrically coupled to the plurality of electric pumps so as to generate electricity for use by the plurality of electric pumps; a gas compression system fluidly coupled to the at least one generator so as to provide fuel for use by the at least one generator; and a combustible fuel vaporization system gaseously coupled to the gas compression system so as to provide at least one of vaporized fuel or gasified fuel, or a combination thereof, to the gas compression system.

An engine system includes an engine configured to combust liquid natural gas and generate an exhaust gas comprising methane; a catalytic reactor coupled downstream of the engine and configured to convert methane into a product through one or more of oxidative coupling of methane (OCM) reaction and steam methane reforming (SMR) reaction; and a recirculation loop configured to recirculate at least a part of the product back to the engine.

A system may include a natural gas engine; and a hydrodynamic device configured to convert mechanical energy of the natural gas engine into heat in a working fluid within the hydrodynamic device. The amount of fluid in the hydrodynamic device may be controlled by an electronically controllable valve, and the amount of fluid in the hydrodynamic device may control a resistive force of the hydrodynamic device. The system may also include a controller in communication with the natural gas engine and the hydrodynamic device, where the controller may be configured to automatically adjust the electronically controllable valve to maintain a working load on the natural gas engine at or above a threshold load.

Some embodiments described herein relate to a method of operating a compression ignition engine. The method of operating the compression ignition engine includes opening an intake valve to draw a volume of air into a combustion chamber, closing an intake valve, and moving a piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of at least about 15:1. The method further includes injecting a volume of fuel into the combustion chamber at an engine crank angle between about 330 degrees and about 365 degrees during a first time period. The fuel has a cetane number less than about 40. The method further includes combusting substantially all of the volume of fuel. In some embodiments, a delay between injecting the volume of fuel into the combustion chamber and initiation of combustion is less than about 2 ms.

A combined heat and power system includes a liquid-cooled internal combustion engine, an air-cooled alternator, an air-to-water heat exchanger, and a coolant-to water heat exchanger. The liquid-cooled internal combustion engine includes a liquid cooling system configured to cool the engine with coolant thereby heating the coolant. The air-cooled alternator is configured to be driven by the internal combustion engine to produce electricity. The alternator includes an air cooling system configured to cool the alternator thereby heating air. The air-to-water heat exchanger is configured to place heated air and water in a heat exchange relationship to preheat the water and cool the air. The coolant-to-water heat exchanger is configured to place heated coolant and preheated water from the air-to-water heat exchanger in a heat exchange relationship to further heat the water and cool the coolant. The coolant-to-water heat exchanger provides heated water to the housing water outlet.