Download or read book Investigation of Relationships Among Microstructure, Rheology, Drag Reduction and Heat Transfer of Drag Reducing Surfactant Solutions written by Yunying Qi and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Drag reducing (DR) surfactant solutions can reduce pumping energy requirements in district heating and cooling (DHC) systems by 30-60%. To enhance the heat transfer ability of DR surfactant solutions, three methods were investigated. Fluted tube-in-tube heat exchangers and installing destructive devices at heat exchanger entrances were found to be very effective with moderate pressure drop penalties. The former is good for new DHC systems while the latter is ideal for existing DHC systems. Ultrasonic energy break up surfactant microstructures and enhance their heat transfer ability was effective for viscoelastic drag reducing surfactant solutions. The destructive devices and ultrasonic energy temporarily destroy the surfactant microstructure which enhances heat transfer. The microstructure recovers quickly and the solution regains its DR ability downstream of the exchanger. Unsaturated hydrocarbon chains with cis and trans configurations with different counterion/surfactant ratios influence the effective DR temperature range of cationic surfactant solutions, their shear degradation, their rheological behavior and their microstructures. Shearing effects on the microstructures of different DR surfactant solutions were studied using SANS. Surfactant microstructures aligned along the flow direction under shear. However, the critical shear rate for the initiation of alignment depends on surfactant microstructure. Differences and their relation to rheological properties and DR abilities are discussed. Shear induced structures (SIS) are accompanied by first normal stress difference (N1). Non-viscoelastic DR systems do not show SIS and N1. Threadlike micelle structures appear to be present in all DR surfactant solutions under shear, however. While some DR surfactant solutions have low extensional/shear viscosity ratios at extensional rates