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Consider the first triangular diagram below, which shows all possible mixtures of methane, oxygen and nitrogen. Air is a mixture of about 21 volume percent oxygen, and 79 volume percent inerts (nitrogen). Any mixture of methane and air will therefore lie on the straight line between pure methane and pure air – this is shown as the blue air-line.
The BE-4 is a staged combustion cycle engine, with a single oxygen-rich preburner, and a single turbine driving both the fuel and oxygen pumps. [53] The cycle is similar to the kerosene-fueled RD-180 currently, although it uses only a single combustion chamber and nozzle.
A schematic diagram of a demethanizer extracting hydrocarbon liquids from natural gas. Raw natural gas consists primarily of methane (CH 4), the shortest and lightest hydrocarbon molecule, along with various amounts of heavier hydrocarbon gases such as ethane (C 2 H 6), propane (C 3 H 8), normal butane (n-C 4 H 10), isobutane (i-C 4 H 10), pentanes and even higher-molecular-mass hydrocarbons.
The fuel turbopump is driven by the fuel-rich preburner, and the oxidizer turbopump is driven by the oxidizer-rich preburner. [ 5 ] [ 4 ] Benefits of the full-flow staged combustion cycle include turbines that run cooler and at lower pressure, due to increased mass flow, leading to a longer engine life and higher reliability.
The gaseous state of water is lighter than air (density 0.804 g/L at STP, average molecular mass 18.015 g/mol) due to water's low molar mass when compared with typical atmospheric gases such as nitrogen gas (N 2). It is non-flammable and much cheaper than helium. The concept of using steam for lifting is therefore already 200 years old.
Amable Liñán introduced a modified mixture fraction in 1991 [6] [7] that is appropriate for systems where the fuel and oxidizer have different Lewis numbers. If L e F {\displaystyle Le_{F}} and L e O 2 {\displaystyle Le_{O_{2}}} are the Lewis number of the fuel and oxidizer, respectively, then Liñán's mixture fraction is defined as
The limiting oxygen concentration is shown in the lower right of the diagram. The limiting oxygen concentration (LOC), [1] also known as the minimum oxygen concentration (MOC), [2] is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of ...
Air–fuel ratio (AFR) is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. The combustion may take place in a controlled manner such as in an internal combustion engine or industrial furnace, or may result in an explosion (e.g., a dust explosion).