Chemical Engineering
N. Hedayati; A. Ramiar
Abstract
The challenge of particle deposition in microchannels has consistently posed issues in nanofluids, adversely impacting the heat transfer rate. This study investigates the novel approach of employing a magnetic field to prevent deposition and enhance the heat transfer of nanoparticles in microchannels, ...
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The challenge of particle deposition in microchannels has consistently posed issues in nanofluids, adversely impacting the heat transfer rate. This study investigates the novel approach of employing a magnetic field to prevent deposition and enhance the heat transfer of nanoparticles in microchannels, utilizing Euler-Lagrange method. The analysis involves the coupled solution of momentum and energy equations, incorporating forces such as Brownian motion, thermophoresis, drag, and volumetric force. The findings within the explored parameters indicate that temperature variations affecting particles beyond the thermal boundary layer have a comparatively minor impact compared to those within the boundary layer. This presents an opportunity for optimizing nanoparticle consumption. Additionally, the study reveals that a non-developed flow at the inlet results in lower particle deposition compared to a developed inlet. The results show that an increase in the Reynolds number from 50 to 300 leads to a 1.75% increase in the distance of particles from the wall. The study also delves into the positioning of the current-carrying wire, demonstrating that placing the wire at the microchannel entrance significantly reduces particle deposition. Furthermore, the results indicate that with an increase in electrical current up to 4 amperes, the efficiency of non-deposition reaches 100%.
H. Abazari Bahnemiri; S. A. A. Oloomi; S. A. A. Mirjalily; A. Zare-Shahabadi
Abstract
In the present research, effects of nanoparticles and changing of tube diameter have been scrutinized on heat transfer parameters in the shell and helically coiled tube heat exchanger. A CFD analysis and also a modeling of the mentioned heat exchager have carried out by writing a code in MATLAB software ...
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In the present research, effects of nanoparticles and changing of tube diameter have been scrutinized on heat transfer parameters in the shell and helically coiled tube heat exchanger. A CFD analysis and also a modeling of the mentioned heat exchager have carried out by writing a code in MATLAB software for two regimes involving forced convection heat trasnfer in single phase fluid flow and sub-cooled boiling. In the case under analysis, considered nanoparticles in this research was Nickel nanoparticles with 0.1 and 1% volumetric concentration. Based on the results, both going up of volume concentration of nanoparticles and increasing of tube diameter are cause to make better heat transfer parameters. In truth, heat transfer coefficient and Nusselt number have been enhanced by 0.1 and 1 % volumetric concentration of Nickel nanoparticles.
Nano-Biotechnology
A. Kumar Singh; R. Patle; M. Das; R. Sanodiya; N. M. Stanley; P. Malkhani
Abstract
Applications of nano-scaled energetic materials in diesel and diesel-biodiesel blends as catalytic agents have emerged contemporarily in pace to develop an efficient and eco-friendly alternative fuel for compression ignition (CI) engines. Inclusion of nanoparticles as additives for CI engine fuels promises ...
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Applications of nano-scaled energetic materials in diesel and diesel-biodiesel blends as catalytic agents have emerged contemporarily in pace to develop an efficient and eco-friendly alternative fuel for compression ignition (CI) engines. Inclusion of nanoparticles as additives for CI engine fuels promises as overall improver of engine performance and emission characteristics. However, simultaneous control on engine performance parameters and emission characteristics is usually difficult. Dispersion of nano-additives improves combustion efficiency by altering specific fuel properties of diesel. Average particle size of 40-50 nm facilitate greater surface-to-volume ratio, hence ensure more complete combustion through further chain reactions during combustion. Nanoparticles as catalytic agents in diesel and its proportionate blends have recently emerged as game changer but their potential is in-fact not fully explored for market acceptability. The following are the major challenges that are to be considered in future researches: (a) There is a need of on-road testing in real ambient conditions, (b) Effects of exhaust emission fuelled with nanocatalysts on human breathing, (c) Overall effects on diesel engines of agricultural tractors and other heavy earth moving machines which are designed for high load factors, and (d) Effects of such modified fuels on driving habits of consumers.
T. J. Malek; S. H. Chaki; M. D. Chaudhary; J. P. Tailor; M. P. Deshpande
Abstract
The effect of Mn doping on Fe3O4 nanocrystalline spinel particles is studied. Two doping concentrations of 10 and 15% Mn were employed. The nanoparticles synthesis was carried out by wet chemical reduction technique. The energy dispersive analysis of X-ray confirmed the stoichiometry of the samples. ...
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The effect of Mn doping on Fe3O4 nanocrystalline spinel particles is studied. Two doping concentrations of 10 and 15% Mn were employed. The nanoparticles synthesis was carried out by wet chemical reduction technique. The energy dispersive analysis of X-ray confirmed the stoichiometry of the samples. The X-ray diffraction technique was used to determine the crystal structure and particles size of the synthesized nanoparticles. The electron microscopy revealed that both the synthesized nanoparticles surfaces have flower-like patterns and the particles are spherical. The optical absorption study showed that the absorption is more in case of 10% Mn doped compared to 15% Mn doped Fe3O4 nanoparticles. The Fourier transform infra-red spectroscopy revealed that both the samples contain characteristics bands. The magnetization variation with temperature with zero field cooled and field cooling conditions for two different applied magnetic fields of 500 Oe and 1000 Oe as well as the hysteresis study was carried out by vibrating sample magnetometer technique. The obtained results are discussed in details.
