Question

Liquid octane (C8H18) is burned completely during the combustion process and exit at a pressure of 4 atm. Determine; a. The air-fuel ratio b- The dew point temperature of the products.

Answer 1

the air fuel ratio = 15.136 kg of air/kg if fuel

the dew point temperature of the products ~ 84.6°C (using steam table have more accuracy than cengel table because the interval range is in steam table, if we use very small  interval range we can get more accurate result value)
liquet octane (igt 8) Product Presame procedunt = 4 x 101.325 kPa 101.385kPa a (3 70 mg).co) 63 = 405 300 km For complete combustion [iamo Cgt sig + n(Ug +3.76 M) g> x (02 ty theo equate on both sides For cusber XES For Oyudragen For oxygen its 3 = 8+893 Cg Hig + 13.5 (043.76 wa) = 800g + 9890 + 125 (3768) Maid Ao fuel ratio = 18.5 x 4.76 kone (299 ks/krd) 8 kml (12 ks demol + 9 kmi ale reg / Kome!) 1795-6 : 15.136 air Alf = 15.136 kg of 114

Pv Pporoduct Nproduct x 4.05.3 kPa 9 kmol (8494(1989 28-76) kow) X 405.3 64 = 56.995 kPa Table A-5, from Cengel Thurmodynamics P= 50 kPa =) T 8).Sec - 75 kPa =) T = 91.76°c P. 56.995-50 X 8132) (91.76 + T= 81.32 75 - 50 B 2 56.995 kPa T= 84.24°C (less accuracy) = T = 84.84°C dew point temperature of duits the pro Ford uring steam table = 100 kPa) more accurate From sheam tables RS-khurmi P=0.566 bar T=84.1990 Cibau p=0.58 bar T=85.09°C P = 0.56995 bar 0.56995-0.56 T = 84.19 dew mint temperature of the products=T=84.638°C 0.58 -0.56 Am ~ 84.6 °C AF dewpoint temperatue the products = 84.6°C x(85.09 -84.19) + = 15:136 kg g air

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