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Performances of falling film evaporators

  • R. Selwyn Jebson (a1) and Mani Iyer (a1)

Summary

The performances of falling film evaporators used in the New Zealand dairy industry for concentrating skim milk, whole milk and buttermilk were evaluated by determining (1) the kg steam used per kg water evaporated, and (2) the heat transfer coefficient of each pass in the evaporators. A computer program was used to calculate the results. The heat transfer coefficients varied from 0·3 to 3·2 kW/m2 per °C and the steam consumption from 0·4 to 0·09 kg steam/kg evaporation. The viscosity of the feed and the momentum of the vapours passing down the tubes were found to be the main factors controlling the heat transfer coefficient. A correlation between the heat transfer coefficient and these factors is presented. Other factors likely to have an influence on the performance are discussed.

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References

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Agarwala, S. P. & Ojha, T. P. 1976 Heat transfer studies in single tube single effect falling film skim milk evaporator. Indian Journal of Dairy Research 29 231233
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Kessler, H. G. 1981 Food Engineering and Dairy Technology p. 235Freising: Verlag A. Kessler
Mincowycz, W. J. & Sparrow, E. M. 1966 Condensation heat transfer in the presence of noncondensables, interfacial resistance, superheating, variable properties, and diffusion. International Journal of Heat and Mass Transfer 9 11251144
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