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Home ‣ Mechanical Engineering ‣ Heat Transfer, Refrigeration and Air Conditioning Comments
  • Question

  • Prandtl number (PN) is given by PN = ?.cp/k.


  • Options
  • A. Yes
  • B. No

  • Correct Answer
  • Yes 

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The by-pass factor of the heating coil is

    • Options
    • A. 0.376
    • B. 0.4
    • C. 0.6
    • D. 0.67
      • Discuss
    • 2. The final relative humidity of the air during cooling and dehumidification is generally __________ than that of entering air.

    • Options
    • A. lower
    • B. higher
      • Discuss
    • 3. In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is

    • Options
    • A. heated and dehumidified
    • B. heated and humidified
    • C. cooled and humidified
    • D. cooled and dehumidified
      • Discuss
    • 4. In absorption vapour systems, the refrigerant widely used is R-12.

    • Options
    • A. Correct
    • B. Incorrect
      • Discuss
    • 5. The colour of the flame of halide torch, in case of leakage of freon refrigerant, will change to

    • Options
    • A. bright green
    • B. yellow
    • C. red
    • D. orange
      • Discuss
    • 6. The transfer of heat by molecular collision is smallest in

    • Options
    • A. solids
    • B. liquids
    • C. gases
    • D. none of these
      • Discuss
    • 7. A composite slab has two layers of different materials with thermal conductivities k1 and k2. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

    • Options
    • A. k1 k2
    • B. k1 + k2
    • C.
    • D.
      • Discuss
    • 8. The wet bulb depression indicates __________ humidity of the air.

    • Options
    • A. absolute
    • B. relative
    • C. specific
      • Discuss
    • 9. If the energy radiated per second per sq. cm. of the surface for wave lengths lying between ?, and ? + d? is represented by (e?.d?), then e? is called

    • Options
    • A. absorptive power
    • B. emissive power
    • C. emissivity
    • D. none of these
      • Discuss
    • 10. In case ofsensible cooling of air, the coil efficiency is given by

    • Options
    • A. B.P.F. - 1
    • B. 1 - B.P.F.
    • C.
    • D. 1 + B.P.F.
      • Discuss

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