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Rheodynamics non-viscous medium in long (cylindrical) pipes: using the Ostwald-De Ville model

Brovatets Oleksandr, Chоvniuk Yuiry, Moskvitina Anna

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

2020

Vol. 9, No 2

19--22

While heating the soil in greenhouses, ground heat exchangers are used, as well as when accumulating heat in soil massifs for further use of heat by heat pumps, or when accumulating heat from solar collectors in heat accumulators. In such cases, a coolant moves in the heat exchangers, which will not freeze or boil, most often these are solutions polyethylene/ethylene glycol, which belong to nonlinear viscous fluids. In this work, the nonisothermal motion of a nonlinear-viscous fluid (within the framework of the Ostwald - de Ville model) in a flat channel with a given heat flow on the wall is investigated. A characteristic feature of the flow of such media is their high thermal sensitivity due to phase and structural transformations. Therefore, with a change in temperature, there is a sharp change in rheological properties. For a number of materials, for example, for polyethylene glycol (ethylene glycol) mixtures, for glycerol solutions, these changes can occur in a fairly narrow temperature range. The flow in a channel is considered, the length of which is much greater than the length of the hydrodynamic and thermal initial sections. The case is investigated when the temperature changes along the channel. Channels of arbitrary cross-section (and, in particular, rectangular and circular) are considered. The situation is analyzed when the temperature changes along the channel, and this change is rather weak in relation to the temperature change along the channel walls (in the transverse direction, that is, in the plane of symmetry). To describe the state of the system, the so-called state diagram (dependence of the temperature on the axis of symmetry of the channel on the heat flux).

Rheological properties of water solutions of non-ionic surfactants

Drzazga M., Kostrzewa E., Gierczycki A.

Chemical and Process Engineering

2010

Vol. 31, z. 3

387-394

Rheological properties of diluted water solutions of non-ionic surfactants such as ethoxylated unsaturated fatty alcohols Rokanol K3, Rokanol K7 and Rokanol Ł18, as well as the product of ethoxylation of technical stearin Rokacet S7 were experimentally examined. In mathematical description of these solutions the power law Ostwald.de Waele model has been employed. Effects of temperature, concentration and structure of surfactants were also tested. An impact of mass ratio of two surface active agents on properties of a binary solution was also examined.

Przedstawiono wyniki badań właściwości reologicznych rozcieńczonych wodnych roztworów niejonowych związków powierzchniowo czynnych, takich jak oksyetylenowane nienasycone alkohole tłuszczowe Rokanol K3, Rokanol K7 i Rokanol Ł18 oraz produkt oksyetylenowania stearyny technicznej Rokacet S7. Do opisu matematycznego roztworów wykorzystano potęgowy model Ostwalda.de Waele. Zbadano wpływ takich czynników, jak stężenie, struktura cząsteczki surfaktanta oraz temperatura na właściwości roztworów oraz zależność lepkości pozornej roztworów dwóch różnych surfaktantów od ich stosunku masowego w roztworze.