Equivalence Ratio (φ)
Calculate the combustion equivalence ratio, φ = AFR_stoichiometric ÷ AFR_actual, dividing the stoichiometric air-fuel ratio by the actual one. The dimensionless result classifies the mixture: φ = 1 is stoichiometric (exact air); φ < 1 is lean (excess air, typical of industrial burners and diesel engines); φ > 1 is rich (lack of air, produces CO and soot, but more power in gasoline engines). The equivalence ratio is the preferred dimensionless parameter in combustion science, linked to excess air (φ = 1/(1+EA)). Enter the stoichiometric and actual air-fuel ratios.
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Razão de equivalência (φ)
A razão de equivalência (φ, phi) é o parâmetro adimensional que a ciência da combustão prefere para caracterizar uma mistura ar-combustível: φ = AFR_estequiométrico ÷ AFR_real. Ela compara a mistura real com a ideal (estequiométrica) e resulta num número limpo e universal, independente do combustível específico. A interpretação é direta e central: φ = 1 é a mistura estequiométrica — ar e combustível na proporção exata. φ < 1 é mistura pobre (lean) — há excesso de ar, sobra oxigênio; típica de queimadores industriais, turbinas a gás e motores diesel, que operam pobres para garantir queima completa, controlar a temperatura e reduzir emissões. φ > 1 é mistura rica (rich) — há falta de ar, sobra combustível; gera CO e fuligem (combustão incompleta), mas é usada em motores a gasolina sob aceleração máxima (mistura rica dá mais potência e resfria a câmara). A razão de equivalência se relaciona com o excesso de ar por φ = 1/(1 + EA): φ = 0,83 corresponde a 20% de excesso de ar. Ela é decisiva em vários fenômenos: os limites de inflamabilidade (uma mistura só queima entre certos φ), a temperatura de chama (máxima perto de φ = 1, levemente rica), a formação de poluentes (NOx pico perto de φ = 1 pela alta temperatura; CO e fuligem em φ > 1; combustão estável e limpa em φ < 1), e a velocidade de chama. Por isso projetar a queima é, em grande parte, escolher e controlar o φ certo para cada objetivo. Informe as relações ar-combustível estequiométrica e real.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.