Engineering Board Exam Reviewer · Thermodynamics · medium

Excess air in combustion is the air supplied in addition to the:

  1. Secondary air
  2. Theoretical (stoichiometric) air
  3. Primary air
  4. Air required for cooling

Answer

B. Theoretical (stoichiometric) air

Solution

Percent excess air = (actual air − theoretical air)/theoretical air × 100%.

More Thermodynamics questions

  1. What is the theoretical air–fuel ratio by mass for complete combustion of octane ( C8H18)? (Mair = 28.97)
  2. What is the theoretical (stoichiometric) air–fuel ratio by mass for the complete combustion of methane ( CH4)? (Air: 21% O2, 79% N2 by…
  3. A material with very low thermal conductivity used to reduce heat transfer is called a/an:
  4. The dimensionless number that represents the ratio of convective to conductive heat transfer at a fluid boundary is the:
  5. Which of the following materials has the highest thermal conductivity?
  6. In a counterflow heat exchanger, the hot fluid cools from 150 °C to 90 °C while the cold fluid is heated from 30 °C to 70 °C. What is the…
  7. A pipe is covered with insulation (k = 0.05 W/m· K) with inner radius 5 cm and outer radius 10 cm. If the temperature difference across…
  8. Using Wien's displacement law ( max T = 2898 m· K), at what wavelength is the emission of the sun (T 5800 K) at a maximum?
  9. If the absolute temperature of a blackbody is doubled, the rate of radiation it emits increases by a factor of:
  10. A small surface ( = 0.8, A = 0.5 m2) at 400 K is surrounded by large walls at 300 K. What is the net radiation heat transfer from the…

All Thermodynamics Reviewer questions