Energetic and Exergetic Assessment of Spiral Heat Exchanger Using Mineral and Oxide Mineral Oil Nanofluid

This paper presents an experimental analysis on the heat transfer and pressure drop enhancement of oil nanofluid flow. In this analysis, the first method has used the helically coiled tube and shell, the oil nanofluids were employed instead of the base fluid (oil) in the second process. the two techniques were used to improve the heat transfer and pressure drop. Nanofluid oil concentrations utilized within range from 1 to 5 percent vol. This paper applied two forms of nanoparticles: copper (Cu (20 nm)) and zirconium oxide (ZrO2 (40 nm)) and base fluid (oil). The influence on the heat transfer coefficient for different factors such as the flow number of Reynolds, the temperature of the nanofluid oil, the concentration and shape of the nanoparticle, and the pressure gradient of the flow have examined. The results indicated that the value of a 40.35 percent in the heat transfer coefficient for Cu + oil and 28.42 percent for ZrO2 + oil increased compared with the base fluid (oil) at 5 percent vol concentration. Using oil nanofluids (Cu, ZrO2 – oil) instead of the base fluid (oil) led to increasing in the heat transfer coefficient and decreasing the pressure. In addition, the result showed that the heat transfer efficiency has enhanced using the helically coiled tube and shell, as well as increasing in the pressure drop was due to the curvature of the tube. Baes on the relationship between viscosity and shear intensity, the oil nanofluid behaviors were similar to the standard Newtonian fluids. Moreover, the related flow and heat transfer methods are used to present the output index. The exergy inflow, exergy destruction and exergy efficiency of oil nanofluid (Cu +oil) were greater than the oil nanofluid (ZrO2 +oil) and oil. The exergy inflow, exergy destruction, and exergy efficiency for the two type of oil nanofluid increased with increasing of nanoparticles concentration.

3D investigations of microscale mixing in helically coiled capillaries

In capillary reactors, improving radial mixing and narrowing the residence time distribution is of great importance for high selectivity and reaction performance. A well-known approach is inducing secondary flow patterns by coiling the capillary around a cylinder. To increase understanding of transport phenomena in helically coiled capillaries non-invasive 3D imaging approaches are required. In this perspective paper, we introduce X-ray-based micro-computed tomography for the investigation of dispersion of iodide in a helically coiled tube. The methodology presented here allows for the direct evaluation of radial concentration fields. By varying Dean number $$Dn$$ D n and modified torsion parameter $${T}^{*}$$ T ∗ , the effect of torsion and curvature on the radial concentration profile can be identified. Detailed knowledge of local radial mixing in helically coiled capillaries will help the precise prediction of reaction progress and selectivity. Graphical abstract