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

  • 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. A composite slab has two layers of different materials with thermal conductivities k1 and k2. If eac
  • D. A composite slab has two layers of different materials with thermal conductivities k1 and k2. If eac

  • Correct Answer
  •  

    • Heat Transfer, Refrigeration and Air Conditioning problems

    Search Results

    • 1. The transfer of heat by molecular collision is smallest in

    • Options
    • A. solids
    • B. liquids
    • C. gases
    • D. none of these
      • Discuss
    • 2. Prandtl number (PN) is given by PN = ?.cp/k.

    • Options
    • A. Yes
    • B. No
      • Discuss
    • 3. 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
    • 4. The final relative humidity of the air during cooling and dehumidification is generally __________ than that of entering air.

    • Options
    • A. lower
    • B. higher
      • Discuss
    • 5. 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
    • 6. The wet bulb depression indicates __________ humidity of the air.

    • Options
    • A. absolute
    • B. relative
    • C. specific
      • Discuss
    • 7. 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
    • 8. 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
    • 9. When the discharge pressure is too high in a refrigeration system, high pressure control is installed to stop the compressor.

    • Options
    • A. Correct
    • B. Incorrect
      • Discuss
    • 10. The critical temperature is the temperature

    • Options
    • A. below which a gas does not obey gas laws
    • B. above which a gas may explode
    • C. below which a gas is always liquified
    • D. above which a gas will never liquified
      • Discuss

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