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On invariants of a convective drying process

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Journal of Engineering Physics and Thermophysics Aims and scope

Abstract

The Lewis relation is proved to be valid in the absence of an analogy between heat and mass transfer. Invariance of temperature and equilibrium curves is established for some drying processes.

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Abbreviations

I:

enthalpy

c:

heat capacity

t, θ:

temperature of the gas and a material, respectively

u, us, ucr.red, umax.h, ueq :

mean, surface, critical reduced, maximum hygroscopic, equilibrium moisture content of the material, respectively

X:

air moisture content

qb :

binding energy of moisture with the material

r0 :

heat of liquid evaporation at 0°C

D:

vapor diffusion coefficient in the gas calculated from the moisture content gradient

f:

specific contact surface of phases, m2/kg

l :

determining dimension

X′, t:

moisture content and temperature of the gas in the boundary layer

y:

normal to the contact surface of phases

α, β:

interphase heat and mass transfer coefficients

λ:

gas thermal conductivity

ρ:

density

τ:

time

Rb=cm(−dθ/du)r:

Reminder number

Nu=αl/λ, Num=βl/D:

heat and mass transfer Nusselt numbers. Indices

g, gas, m:

material

s:

surface

d.g:

dry gas

l :

liquid

v:

vapor

sat:

saturated

w.t:

wet-bulb thermometer

f:

final, index 0 stands for parameters at the dryer inlet

References

  1. A. B. Lykov, in: The Theory of Drying [in Russian], Moscow (1968), pp. 115–128.

  2. V. I. Konovalov, Zh. Prikl. Khimii,59, No. 9, 2096–2107 (1986).

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  3. P. S. Kuts, V. V. Fedorovich, É. G. Tutova, et al., in: Heat and Mass Transfer: Research and Developments [in Russian], Minsk (1981), pp. 46–49.

  4. V. I. Mushtaev, V. M. Ul'yanov, and A. S. Timonin, Pneumatransport Drying [in Russian], Moscow (1984).

  5. M. M. Razin, T. G. Russkikh, and L. A. Smirnova, in: Modern Apparatus for Treatment of Heterogeneous Media [in Russian], Leningrad (1986), pp. 25–29.

  6. O. Krisher, Scientific Principles of Drying Technology [Russian translation], Moscow (1961).

  7. V. F. Frolov, in: Drying Modeling of Disperse Materials [in Russian], Leningrad (1987), pp. 20–34.

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Authors
  1. M. M. Razin
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Additional information

Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 4, pp. 442–448, October, 1992.

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Razin, M.M. On invariants of a convective drying process. J Eng Phys Thermophys 63, 1009–1015 (1992). https://doi.org/10.1007/BF00853351

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  • DOI: https://doi.org/10.1007/BF00853351

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