Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

CONJUGATED PROBLEM OF CONVECTIVE HEAT TRANSFER IN RECUPERATIVE HEAT EXCHANGERS WITH A NON−NEWTONIAN HEAT CARRIER

Get access (open in a dialog) DOI: 10.1615/IHTC6.1860
pages 367-372

Abstrakt

The methods of theoretical calculation of heat exchangers at parallel (co-current and counter-current) flow of a Newtonian and a non-Newtonian heat carriers, separated by a highly heat conducting barrier, are suggested. The statement of the problem is conjugated. The first, engineering, method is based on the heat balances. By means of this method, approximate relationships are obtained for the effect of non-Newtonian properties on the characteristics of heat transfer. To describe a mechanical behaviour of the disperse non-Newtonian heat carrier, a model of viscoplastic medium is chosen. With increase in plasticity of the medium, heat transfer is intensified (according to the power law). The second method is based on the boundary layer of the finite thickness. Application of the integral method reduces the original system to the Cauchy problem for two ordinary differential equations. Its solution is obtained by the numerical method. In this case, a lesser discrepancy and higher reliability of numerical relations are secured. With increase in plasticity, the boundary layer thickness decreases, with subsequent intensification of heat transfer. The case of dispersed liquid viscoplastic heat carriers, whose non-Newtonian behaviour is caused by external physical fields, is studied separately. These fields are represented by electrorheological suspensions. With the help of the methods suggested, it is shown that the external electric field provides flexible and effective control of the characteristics of heat exchangers.