Heat transfer intensification of nanomaterial with involve of swirl flow device concerning entropy generation

The thermal features of hybrid nano-powder turbulent motion through a pipe employing helical turbulator is numerically simulated via Finite Volume Method (FVM). The hybrid nanofluid (MWCNTs + Fe3O4 + H2O) is obtained by uniformly dispersing MWCNTs + Fe3O4 nanomaterials in H2O. The characteristics features of thermal energy transfer of hybrid nanofluid are investigated by varying the pitch ratio (P) of the helical turbulator and Reynolds number (Re) of the fluid. The outputs of the study are depicted in terms of contour plots of temperature, velocity, frictional irreversibility Sgen,f, and thermal irreversibility Sgen,th. The variation of Sgen,f, and Sgen,th with changing P and Re are also displayed by 3D plots. It is found that making the fluid more turbulent by increasing Re, the temperature of the fluid drops whereas the fluid velocity augments. The frictional irreversibility enhances, whereas the thermal irreversibility drops with the increasing turbulent motion. The decreasing P causes to drop the temperature of the higher turbulent fluid flow, while opposite effect is observed for smaller Re. The decreasing P causes to enhance the fluid mixing and thus augments the fluid velocity. Sgen,f and Sgen,th both augment with decreasing P. The comparison of current outputs with the older article shows an acceptable accuracy. The results of the present investigation will be useful in modelling of efficient thermal energy transfer systems.

Energy consumption of emulsification processes in small-sized mix apparatuses

There is given in this thesis a general method of calculation of power consumption for emulgation in systems liquid-liquid in small-size mixing devices (rotor-pulsation apparatuses and rotor-disc mixers). This mixing devices, have shown a high efficiency at processing of liquid-liquid systems and are wide using chemical processes. The base of calculation method is an energy ratio to describe of developed turbulent motion, pulsation intensity of which is enough for create of dispersed particles of given size and concentration, which provide a necessary surface of phases contact. It is shown, that in determination of energy consumption it is need to take in account energy dissipation processes, due to viscous friction forces, which have a significant influence at high gradients of turbulent motion. There is obtained a ratio, which connects an angular velocity of rotor rotation of mixing device and a characterized size of dispersed phase particles.There is given an experimental dependencies of consumed power of rotor-disc mixers on rotor rotations number of mixing device and characterized sizes of dispersed particles for systems water-diesel fuel. It was determined, that are decreasing of dispersed particles sizes and in increasing of volumetric flow of processing mixture a value of consumed power increases, and it is related with by increase of energy consumption for creating of interphase surface. It was determined, that a power, consumed by rotor-disc mixer, for emulsion making with averaged dispersion size of particles at range 5-25 mkm, increases by increase of rotation numbers ~n0.37. Comparison of theoretical equations and experimental data have shown adequacy of supposed calculation method of energy consumption.

Spatial power spectra of dust across the Local Group: No constraint on disc scale height

ABSTRACT We analyse the 1D spatial power spectra of dust surface density and mid to far-infrared emission at $24\!-\!500\, \mu$m in the LMC, SMC, M31, and M33. By forward-modelling the point spread function (PSF) on the power spectrum, we find that nearly all power spectra have a single power-law and point source component. A broken power-law model is only favoured for the LMC 24 μm MIPS power spectrum and is due to intense dust heating in 30 Doradus. We also test for local power spectrum variations by splitting the LMC and SMC maps into 820 pc boxes. We find significant variations in the power-law index with no strong evidence for breaks. The lack of a ubiquitous break suggests that the spatial power spectrum does not constrain the disc scale height. This contradicts claims of a break where the turbulent motion changes from 3D to 2D. The power spectrum indices in the LMC, SMC, and M31 are similar (2.0–2.5). M33 has a flatter power spectrum (1.3), similar to more distant spiral galaxies with a centrally-concentrated H2 distribution. We compare the power spectra of H i, CO, and dust in M31 and M33, and find that H i power spectra are consistently flatter than CO power spectra. These results cast doubt on the idea that the spatial power spectrum traces large scale turbulent motion in nearby galaxies. Instead, we find that the spatial power spectrum is influenced by (1) the PSF on scales below ∼3 times the FWHM, (2) bright compact regions (30 Doradus), and (3) the global morphology of the tracer (an exponential CO disc).