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We see that the adiabatic flame temperature of the constant pressure process is lower than that of the constant volume process. This is because some of the energy released during combustion goes, as work, into changing the volume of the control system. Adiabatic flame temperatures and pressures as a function of ratio of air to iso-octane.
For example, the adiabatic flame temperature uses this approximation to calculate the upper limit of flame temperature by assuming combustion loses no heat to its surroundings. In meteorology , adiabatic expansion and cooling of moist air, which can be triggered by winds flowing up and over a mountain for example, can cause the water vapor ...
The adiabatic flame temperature of a given fuel and oxidizer pair is that at which the gases achieve stable combustion. Oxy – dicyanoacetylene 4,990 °C (9,000 °F) [ 69 ] Oxy – acetylene 3,997 °C (7,200 °F) [ 70 ]
can be approximated to the flame temperature of the fuel used. The flame temperature can be approximated to the adiabatic flame temperature of the fuel with corresponding air-to-fuel ratio and compression pressure, . can be approximated to the inlet air temperature. This formula only gives the ideal thermal efficiency.
Since the heat of combustion of these elements is known, the heating value can be calculated using Dulong's Formula: HHV [kJ/g]= 33.87m C + 122.3(m H - m O ÷ 8) + 9.4m S where m C , m H , m O , m N , and m S are the contents of carbon, hydrogen, oxygen, nitrogen, and sulfur on any (wet, dry or ash free) basis, respectively.
The maximum temperature of about 2,800 °C (5,100 °F) is achieved with an exact stoichiometric mixture, about 700 °C (1,300 °F) hotter than a hydrogen flame in air. [ 7 ] [ 8 ] [ 9 ] When either of the gases are mixed in excess of this ratio, or when mixed with an inert gas like nitrogen, the heat must spread throughout a greater quantity of ...
Flame speed is used along with adiabatic flame temperature to help determine the engine's efficiency. According to one source, "...high flame-speed combustion processes, which closely approximate constant-volume processes, should reflect in high efficiencies. [4] "
This high flame temperature is partially due to the absence of hydrogen in the fuel (dicyanoacetylene is not a hydrocarbon) thus there is no water among the combustion products. Cyanogen, with the formula (CN) 2, produces the second-hottest-known natural flame with a temperature of over 4,525 °C (8,177 °F) when it burns in oxygen. [11] [12]