Engineering Board Exam Reviewer · Thermodynamics · hard
What is the theoretical (stoichiometric) air–fuel ratio by mass for the complete combustion of methane ( CH4)? (Air: 21% O2, 79% N2 by mole; Mair = 28.97)
- 4.00 kg air/kg fuel
- 9.52 kg air/kg fuel
- 15.12 kg air/kg fuel
- 17.24 kg air/kg fuel
Answer
D. 17.24 kg air/kg fuel
Solution
CH4 + 2( O2 + 3.76N2) CO2 + 2 H2O + 7.52 N2. A/F = 2(4.76)(28.97)/16 = 17.24.
More Thermodynamics questions
- A material with very low thermal conductivity used to reduce heat transfer is called a/an:
- The dimensionless number that represents the ratio of convective to conductive heat transfer at a fluid boundary is the:
- Which of the following materials has the highest thermal conductivity?
- 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…
- 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…
- 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?
- If the absolute temperature of a blackbody is doubled, the rate of radiation it emits increases by a factor of:
- 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…
- What is the rate of radiation emitted by a 1 m2 blackbody surface at 500 K? ( = 5.67 × 10-8 W/m2· K4)
- A composite wall consists of 10 cm of material (k = 0.5 W/m· K) and 5 cm of insulation (k = 0.05 W/m· K). If the temperature difference…