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MCQs

Total Questions : 765 | Page 77 of 77 pages
Question 761. The overall efficiency of the compressed air system is the
  1.    Ratio of shaft output of the air motor to the shaft input to the compressor
  2.    Product of shaft output of air motor and shaft input to the compressor
  3.    Ratio of shaft input to the compressor to the shaft output of air motor
  4.    None of these
 Discuss Question
Answer: Option A. -> Ratio of shaft output of the air motor to the shaft input to the compressor
Question 762. If p₁, is the pressure of air entering the L.P. cylinder and p₂ is the pressure of air leaving the L.P. cylinder (or inter-cooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D₁ = Dia. of L.P. cylinder, and D₂ = Dia. of H.P. cylinder)
  1.    None of these
  2.    D₁/D₂ = p₁/p₂
  3.    D₁/D₂ = p₁ p₂
  4.    D₁/D₂ = p₂/p₁
 Discuss Question
Answer: Option D. -> D₁/D₂ = p₂/p₁
Question 763. In a jet engine, the air-fuel ratio is
  1.    2.0840277777778
  2.    1.6673611111111
  3.    1.2506944444444
  4.    2.5006944444444
 Discuss Question
Answer: Option D. -> 2.5006944444444
Question 764. The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
  1.    All of these
  2.    Clearance volume and leakages
  3.    Pressure drop across the valves
  4.    Superheating in compressor
 Discuss Question
Answer: Option A. -> All of these
Question 765. For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p₂ is given by
  1.    p₂ = (p₁ + p₃)/2
  2.    P₂ = Pa × p₃/p₁
  3.    p₂ = Pa p₃/p₁
  4.    p₂ = p₁. p₃
 Discuss Question
Answer: Option D. -> p₂ = p₁. p₃

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