Comments on “Analysis of heat transfer and irreversibility of ORC evaporator for selecting working fluid and operating conditions”

Awad, Mohamed M.

doi:10.2298/tsci200421170a

Cited by 4 publications

(1 citation statement)

References 19 publications

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“…The reason seems to arise from the very different viscosities of the components. A perfect lamellar system of different components i would have the average viscosity [35,36]:…”

Section: Figurementioning

confidence: 99%

Tunable viscosity modification with diluted particles: when particles decrease the viscosity of complex fluids

Gvaramia

Mangiapia²,

Pipich

et al. 2019

Colloid Polym Sci

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While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations. Extended studies and theories on non-spherical particles find a more complicated behavior, but still a steady increase. Involving platelets in combination with complex fluids displays an even more complex scenario that we analyze experimentally and theoretically as a function of platelet diameter, to find the underlying concepts. Using a broad toolbox of different techniques we were able to decrease the viscosity of crude oils although solid particles were added. This apparent contradiction could lead to a wider range of applications.Introduction. The demand of viscosity modifications by solid particles has many applications in the field of food science [1] and oil recovery [2]. The simplest theoretical description was found by Einstein for diluted spherical particles [3]. At that point, the predicted changes of the viscosity were small, especially for large dilutions in the concentration range of 1%vol. However, applications usually manifold either at large concentrations (as in the case of chocolate [4]) or in asymmetric particles, such as clay, which has many uses [5]. Therefore, the theoretical concepts became more complicated [6,7], and the large number of possibilities opens up a wide range of inter-pretations.The medium in nearly all these cases has been assumed to be a simple liquid. However, the response of complex fluids [8,9] to particles [10,11] can be more complicated [12,13], and, therefore, back coupling might be possible. In our past studies we have studied the lubrication effect, which describes the lamellar ordering [14] of a complex fluid, i.e a microemulsion (µE) next to a hydrophilic wall. This ordering allows the domains for facilitated sliding along the surface [13]. In neutron scattering studies we have found that the typical relaxation times in these lamellae are also faster than in the bulk. So for platelet particles, a facilitated flow behavior (lower viscosity) might be expected [12]. The change of platelet diameters revealed that the perfection of lamellar modes is increasing with increasing platelet diameter. Consequently, large platelets would serve the aim of reduced viscosities better than small ones.Until now, the studied liquids consisted of components with highly similar viscosities. Therefore, the rearrangement of domain structures resulted in similar viscosities, and the highly desired case of viscosity reduction was not found.

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“…The reason seems to arise from the very different viscosities of the components. A perfect lamellar system of different components i would have the average viscosity [35,36]:…”

Section: Figurementioning

confidence: 99%