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Chemical Engineering :: Heat Transfer

  1. What is the steam economy in case of a single effect evaporator system ?

  2. A.
    1
    B.
    >1
    C.
    < 1
    D.
    0.1

  3. If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length

  4. A.
    ha = hl
    B.
    ha = 2hl
    C.
    ha = 0.5 hl
    D.
    ha = 0.75 hl

  5. jH factor for heat transfer is not a function of the __________ number.

  6. A.
    Reynolds
    B.
    Nusselt
    C.
    Grashoff
    D.
    both (b) & (c)

  7. The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by

  8. A.
    forced convection
    B.
    natural convection
    C.
    transient conduction
    D.
    steady state conduction

  9. The energy radiated from a surface Q at absolute temperature T is related as

  10. A.
    QT2
    B.
    QT4
    C.
    QT3
    D.
    none of these

  11. Baffles are provided in heat exchangers to increase the

  12. A.
    fouling factor
    B.
    heat transfer area
    C.
    heat transfer co-efficient
    D.
    heat transfer rate

  13. 200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 x 10-3 kg/m2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)

  14. A.
    0.5
    B.
    0.05
    C.
    0.1
    D.
    0.15

  15. In case of a vertical tube evaporator, with increase in the liquor level, the

  16. A.
    capacity of the evaporator is decreased.
    B.
    capacity of the evaporator is increased.
    C.
    true temperature drop increases.
    D.
    both (b) and (c).

  17. The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.

  18. A.
    wavelength of radiation
    B.
    nature of the body
    C.
    temperature of the body
    D.
    none of these

  19. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally

  20. A.
    decreases
    B.
    increases
    C.
    remains unchanged
    D.
    increases exponentially