Cuvillier
Struktur-Wirkungsbeziehungen bei der Verminderung der Wandreibung in Strömungssystemen durch supramolekulare Strukturen
Abstract
dc:descriptionFlowing liquids in pipe systems cause pressure drops and energy losses and can be responsible for the initiation of flow induced localized corrosion (FILC). Initiation of FILC is affected by unfavourable geometric conditions in flow systems and local flow intensities above critical values. Many technical systems are concerned, e.g. in the field of oil and gas production, pipeline transportation, chemical plants or power stations. Critical flow intensities are generally expressed in terms of wall shear stresses as a value for the friction between turbulent flowing liquids and the wall. High molecular polymers and surface active compounds can influence a turbulent flow by reducing the wall shear stress to values which are uncritical for destruction of protective surface layers and thus can reduce the likelihood of FILC. In the framework of this thesis globular structures of hyperbranched polymers (e.g. polyglycerols, polyethylene imines) were investigated in order to find out if hyperbranched polymers are able to reduce wall shear stresses and if they have a higher resistance to degradation in high shear fields compared to surface active compounds like surfactants. It was proved by electrochemical and rheological investigations that globular structures like polyglycerols and polyethylene imines as well exert flow improving properties when the molecular size is high enough. Electrochemical and rheological measurements yield different results on the flow improving properties. This is explained by the effect of local flow intensities on the near-wall concentration of additives yielding an increase of the near-wall liquid viscosity and thus influences the interaction between the flowing liquid and the wall. This may already result in a decrease of the flow induced corrosion attack in flow systems. In summary, it was found out that hyperbranched polymers are a new class of polymers with a new supramolecular structure which exhibits as well as high molecular compounds and surface active compounds flow improving properties.
Degree
thesis:*- Grantor dc:publisher
- Cuvillier
- Year dc:date
- 2008
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Hörstemeier, Michaela
- Contributors dc:contributor
-
- Schmitt, Günter
Subjects
dc:subject × 11Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger