5 research outputs found
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Investigation of Effect of Aluminium Oxide Nanoparticles on the Thermal Properties of Water-Based Fluids in a Double Tube Heat Exchanger
yesThe thermal behavior of aluminium oxide-water nanofluid in a double pipe carbon steel heat
exchanger was investigated in the present study. The overall heat transfer coefficient, Nusselt, and heat
transfer coefficient of nanofluid were compared with the base fluid. The volume fraction of the
nanoparticles was 1%. By adding nanoparticles to the fluid, the thermal properties of the base fluid
improved significantly. The hot and cold fluid flow was considered counter-current, and the nanofluid
was pumped into the inner tube and once into the outer tube, and the flow rate of each fluid was 0.05
kg/s. The convective heat transfer and the overall heat transfer coefficient enhanced 94% and 253% for
the hot fluid flow in the outer tube and 308 % and 144% for the hot fluid flow in the inner tube,
respectively. The pressure drop calculations also showed that the pressure drop would not change
significantly when using nanofluid
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Distribution and discovery of oceanic natural gas hydrates
NoA crystalline solid called a gas hydrate has gas molecules surrounded by water molecules. There are several gases with suitable structures for the production of hydrates, but methane-rich gas hydrates are more common and form in seas and on the ocean. The place of hydrates formation is usually the sediment of the ocean floor and the polar regions, which largely covered with ice. It is also found in large quantities in combination with ambient ice in the ever-frozen polar regions. The importance of gas hydrates is due to the great ability of gas hydrates in natural gas storage, which makes it attractive to use them for the purposes of storing and transporting natural gas and other gases as a competitor to liquefaction and condensing methods. Due to the significance potential of these reserves as the world's future energy supplier and their direct impact on changes in climate conditions due to the greenhouse effect of methane, as well as their geological risks during water hydrocarbon discoveries, marine science researchers have been studying them over the past few years. Acoustic and seismic methods are helpful instruments for measuring subterranean hydrated reserves because there is not the technology to measure hydrated reserves directly
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Hydrodesulfurization of crude oil over Co-Mo catalysts in a slurry reactor
NoIn this paper, hydrodesulfurization
(HDS) of crude oil in the three-phase slurry reactor
over cobalt – molybdenum catalyst (CoMo / ɣ-
AL2O3) is studied. Effects of space velocity and
length of reactor on the conversion rate and
catalyst effectiveness for HDS process have been
investigated. Kinetics of the reaction rate for this
process is primarily and Arrhenius equation for
the rate constant is used. The results show that
the effectiveness factor for catalyst along the
length of reactor is decreased about 83%.
By increasing liquid velocity from 4 to 10 1/s,
the conversion of sulfur components is decreased
about 22% at the temperature of 523 K. At the
same temperature, by increasing liquid velocity
from 36 to 84 1/s conversion is reduced to 25%.
The results of the variation of the dimensionless
reaction rate against conversion show that with
increasing conversion, the reaction rate
decreases and the reaction is stopped when the
conversion is 100%
Methanol and sodium chloride inhibitors impact on carbon dioxide hydrate formation
Given the importance of hydrate formation, scientists have studied its nature and dealt with its formation in the operating systems and so far many compounds have been studied and applied in this regard including alcohols and salts. Determining thermodynamic equilibrium conditions for hydrate formation will be the subject of this study and the additives such as methanol, sodium chloride and their mixture within the weight percentages of 5%–20% is used that changes the thermodynamic conditions governing the problem including temperature and pressure and causes the formation pressure of methane and carbon dioxide gas hydrates to be higher than the case without additives.MATLAB and Hydoff software programs are used for solving equations and obtaining the relevant results. The results indicated that the proposed model is capable of anticipating the pure carbon dioxide hydrate formation and also to make sure, the obtained results were compared with the results obtained by the experimental and laboratory in this field and the results indicated that the accuracy of the model is very desirable and could be used in the process and the mentioned conditions with high reliability. Maximum error was 5% and the minimum error with experimental data was 1.55%. Keywords: Hydrates, Carbon dioxide, Temperature, Pressure, Modelin