Abstract: Computational fluid dynamics (CFD) simulations
carried out in this paper show that spacer orientation has a major
influence on temperature patterns and on the heat transfer rates. The
local heat flux values significantly vary from high to very low values
at each filament when spacer touches the membrane surface. The
heat flux profile is more uniform when spacer filaments are not in
contact with the membrane thus making this arrangement more
beneficial. The temperature polarization is also found to be less in
this case when compared to the empty channel.
Abstract: The draw solute separation process in Forward
Osmosis desalination was simulated in Aspen Plus chemical process
modeling software, to estimate the energy consumption and compare
it with other desalination processes, mainly the Reverse Osmosis
process which is currently most prevalent. The electrolytic chemistry
for the system was retrieved using the Elec – NRTL property method
in the Aspen Plus database. Electrical equivalent of energy required
in the Forward Osmosis desalination technique was estimated and
compared with the prevalent desalination techniques.
Abstract: The efficiency of chitosan beads processed from 4
marine animal shells; white leg shrimp (Litopenaeus vannamei), mud
crab (Scylla sp.), horseshoe crab (Carcinoscorpius rotundicauda),
and cuttlefish bone (Sepia sp.), for the adsorption experiments of
ammonia and formaldehyde were investigated. The porosities of
chitosan from the shells looked like beads were distinctly examined
under SEM. The original pores of those shells on the surface areas
compose of evenly fine pores. The shell beads of cuttlefish bone and
horseshoe crab show the larger probably even porosity, while on
those white leg shrimp and mud crab contain various large and fine
pores. The best adsorption at pH 9 in 18 mg/l ammonia at 2 hours
yield on cuttlefish bone, horseshoe crab, mud crab and white leg
shrimp with the average percent of 59.12, 51.45, 45.66 and 43.52,
respectively. Within 30 minutes the formaldehyde absorbers (at pH 5
in 8 μg/ml) revealed 46.27, 26.56, and 18.04 percent capacities in
cuttlefish bone, mud crab and white leg shrimp beads; while 22.44
percent in the horseshoe crab at pH 7. The adsorption capacities and
the amounts of beads showed a positive correlation. The adsorption
capacity relationship between pH and the gas concentrations were
affected by these qualities of chitosan beads.
Abstract: A Rotary Disc Contactor with inner diameter of
9.1cm and maximum operating height of 40cm has been used to
investigate break up phenomenon. Water-Toluene, Water as
continuous phase and Toluene as dispersed phase, was selected as
chemical system in the experiments. The mentioned chemical system
has high interfacial tension so it was possible to form big drops
which permit accurate investigation on break up phenomenon as well
as the first and second critical rotor speeds.
In this study, Break up phenomenon has been studied as a function
of mother drop size, rotor speed and continuous phase height. Further
more; the effects of mother drop size and continuous phase height on
the first and second critical rotor speeds were investigated. Finally,
two modified correlations were proposed to estimate the first and
second critical speeds.
Abstract: Iron ore and coal are the two major important raw
materials being used in Iron making industries. Usually ore fines
containing around 5% Alumina are rejected due to higher proportion
of alumina. Therefore, a technology or process which may reduce
the alumina content by 2% by beneficiation process will be highly
attractive . In addition fine coals with ash content is used nearly 12%
is directly injected in blast furnace. Fast fluidization is a technology
by using dry beneficiation of coal and iron ore can be done. During
the fluidization process the iron ore band coal is fluidized at high
velocity in the riser of a fast fluidized bed, the heavier and coarse
particles is generally settled at the bottom in a dense zone of the riser
while the finer and lighter particle are entrained to the top dilute zone
and then via a cyclone is fed back to the bottom of the riser column.
Most of the alumina and low ash fine size coals being lighter are
expected to move up to the riser and by a natural beneficiation of
ores is expected to take place in the riser. Therefore in this study an
attempt has been made for dry beneficiation of iron ore and coal in a
fluidized bed and its hydrodynamic characterization.
Abstract: Chemical detection is still a continuous challenge when
it comes to designing single-walled carbon nanotube (SWCNT)
sensors with high selectivity, especially in complex chemical
environments. A perfect example of such an environment would be in
thermally oxidized soybean oil. At elevated temperatures, oil oxidizes
through a series of chemical reactions which results in the formation of
monoacylglycerols, diacylglycerols, oxidized triacylglycerols, dimers,
trimers, polymers, free fatty acids, ketones, aldehydes, alcohols,
esters, and other minor products. In order to detect the rancidity of
oxidized soybean oil, carbon nanotube chemiresistor sensors have
been coated with polyethylenimine (PEI) to enhance the sensitivity
and selectivity. PEI functionalized SWCNTs are known to have a high
selectivity towards strong electron withdrawing molecules. The
sensors were very responsive to different oil oxidation levels and
furthermore, displayed a rapid recovery in ambient air without the
need of heating or UV exposure.
Abstract: This paper proposes a new optimization techniques
for the optimization a gas processing plant uncertain feed and
product flows. The problem is first formulated using a continuous
linear deterministic approach. Subsequently, the single and joint
chance constraint models for steady state process with timedependent
uncertainties have been developed. The solution approach
is based on converting the probabilistic problems into their
equivalent deterministic form and solved at different confidence
levels Case study for a real plant operation has been used to
effectively implement the proposed model. The optimization results
indicate that prior decision has to be made for in-operating plant
under uncertain feed and product flows by satisfying all the
constraints at 95% confidence level for single chance constrained and
85% confidence level for joint chance constrained optimizations
cases.
Abstract: The knowledge base of welding defect recognition is
essentially incomplete. This characteristic determines that the recognition results do not reflect the actual situation. It also has a further influence on the classification of welding quality. This paper is
concerned with the study of a rough set based method to reduce the influence and improve the classification accuracy. At first, a rough set
model of welding quality intelligent classification has been built. Both condition and decision attributes have been specified. Later on, groups
of the representative multiple compound defects have been chosen
from the defect library and then classified correctly to form the
decision table. Finally, the redundant information of the decision table has been reducted and the optimal decision rules have been reached. By this method, we are able to reclassify the misclassified defects to
the right quality level. Compared with the ordinary ones, this method
has higher accuracy and better robustness.
Abstract: The production of ethyl tert-butyl ether (ETBE) was
simulated through Aspen Plus. The objective of this work was to use
the simulation results to be an alternative platform for ETBE
production from naphtha cracking wastes for the industry to develop.
ETBE is produced from isobutylene which is one of the wastes in
naphtha cracking process. The content of isobutylene in the waste is
less than 30% weight. The main part of this work was to propose a
process to save the environment and to increase the product value by
converting a great majority of the wastes into ETBE. Various
processes were considered to determine the optimal production of
ETBE. The proposed process increased ETBE production yield by
100% from conventional process with the purity of 96% weight. The
results showed a great promise for developing this proposed process
in an industrial scale.
Abstract: Silver nano-particles have been used for antibacterial
purpose and it is also believed to have removal of odorous compounds,
oxidation capacity as a metal catalyst. In this study, silver
nano-particles in nano sizes (5-30 nm) were prepared on the surface of
NaHCO3, the supporting material, using a sputtering method that
provided high silver content and minimized conglomerating problems
observed in the common AgNO3 photo-deposition method. The silver
nano-particles were dispersed by dissolving Ag-NaHCO3 into water,
and the dispersed silver nano-particles in the aqueous phase were
applied to remove inorganic odor compounds, H2S, in a scrubbing
reactor. Hydrogen sulfide in the gas phase was rapidly removed by the
silver nano-particles, and the concentration of sulfate (SO4
2-) ion
increased with time due to the oxidation reaction by silver as a
catalyst. Consequently, the experimental results demonstrated that the
silver nano-particles in the aqueous solution can be successfully
applied to remove odorous compounds without adding additional
energy sources and producing any harmful byproducts
Abstract: Understanding the cell's large-scale organization is an
interesting task in computational biology. Thus, protein-protein
interactions can reveal important organization and function of the
cell. Here, we investigated the correspondence between protein
interactions and function for the yeast. We obtained the correlations
among the set of proteins. Then these correlations are clustered using
both the hierarchical and biclustering methods. The detailed analyses
of proteins in each cluster were carried out by making use of their
functional annotations. As a result, we found that some functional
classes appear together in almost all biclusters. On the other hand, in
hierarchical clustering, the dominancy of one functional class is
observed. In brief, from interaction data to function, some correlated
results are noticed about the relationship between interaction and
function which might give clues about the organization of the
proteins.
Abstract: This paper unifies power optimization approaches in
various energy converters, such as: thermal, solar, chemical, and
electrochemical engines, in particular fuel cells. Thermodynamics
leads to converter-s efficiency and limiting power. Efficiency
equations serve to solve problems of upgrading and downgrading of
resources. While optimization of steady systems applies the
differential calculus and Lagrange multipliers, dynamic optimization
involves variational calculus and dynamic programming. In reacting
systems chemical affinity constitutes a prevailing component of an
overall efficiency, thus the power is analyzed in terms of an active
part of chemical affinity. The main novelty of the present paper in the
energy yield context consists in showing that the generalized heat
flux Q (involving the traditional heat flux q plus the product of
temperature and the sum products of partial entropies and fluxes of
species) plays in complex cases (solar, chemical and electrochemical)
the same role as the traditional heat q in pure heat engines.
The presented methodology is also applied to power limits in fuel
cells as to systems which are electrochemical flow engines propelled
by chemical reactions. The performance of fuel cells is determined by
magnitudes and directions of participating streams and mechanism of
electric current generation. Voltage lowering below the reversible
voltage is a proper measure of cells imperfection. The voltage losses,
called polarization, include the contributions of three main sources:
activation, ohmic and concentration. Examples show power maxima
in fuel cells and prove the relevance of the extension of the thermal
machine theory to chemical and electrochemical systems. The main
novelty of the present paper in the FC context consists in introducing
an effective or reduced Gibbs free energy change between products p
and reactants s which take into account the decrease of voltage and
power caused by the incomplete conversion of the overall reaction.
Abstract: The adsorption properties of CO and H2 on iron-based
catalyst with addition of Zr and Ni were investigated using
temperature programmed desorption process. It was found that on the
carburized iron-based catalysts, molecular state and dissociative state
CO existed together. The addition of Zr was preferential for the
molecular state adsorption of CO on iron-based catalyst and the
presence of Ni was beneficial to the dissociative adsorption of CO. On
H2 reduced catalysts, hydrogen mainly adsorbs on the surface iron
sites and surface oxide sites. On CO reduced catalysts, hydrogen
probably existed as the most stable CH and OH species. The addition
of Zr was not benefit to the dissociative adsorption of hydrogen on
iron-based catalyst and the presence of Ni was preferential for the
dissociative adsorption of hydrogen.
Abstract: In the present study, a heterogeneous and
homogeneous gas flow dispersion model for simulation and
optimisation of a large-scale catalytic slurry reactor for the direct
synthesis of dimethyl ether (DME) from syngas and CO2, using a
churn-turbulent regime was developed. In the heterogeneous gas flow
model the gas phase was distributed into two bubble phases: small
and large, however in the homogeneous one, the gas phase was
distributed into only one large bubble phase. The results indicated
that the heterogeneous gas flow model was in more agreement with
experimental pilot plant data than the homogeneous one.
Abstract: We have developed a microfluidic device system for the continuous producting of nanoparticles, and we have clarified the relationship between the mixing performance of reactors and the particle size. First, we evaluated the mixing performance of reactors by carring out the Villermaux–Dushman reaction and determined the experimental conditions for producing AgCl nanoparticles. Next, we produced AgCl nanoparticles and evaluated the mixing performance and the particle size. We found that as the mixing performance improves the size of produced particles decreases and the particle size distribution becomes sharper. We produced AgCl nanoparticles with a size of 86 nm using the microfluidic device that had the best mixing performance among the three reactors we tested in this study; the coefficient of variation (Cv) of the size distribution of the produced nanoparticles was 26.1%.
Abstract: Mycophenolic acid “MPA" is a secondary metabolite
of Penicillium bervicompactum with antibiotic and
immunosuppressive properties. In this study, fermentation process
was established for production of mycophenolic acid by Penicillium
bervicompactum MUCL 19011 in shake flask. The maximum MPA
production, product yield and productivity were 1.379 g/L, 18.6 mg/g
glucose and 4.9 mg/L.h respectively. Glucose consumption, biomass
and MPA production profiles were investigated during fermentation
time. It was found that MPA production starts approximately after
180 hours and reaches to a maximum at 280 h. In the next step, the
effects of methionine and acetate concentrations on MPA production
were evaluated. Maximum MPA production, product yield and
productivity (1.763 g/L, 23.8 mg/g glucose and 6.30 mg/L. h
respectively) were obtained with using 2.5 g/L methionine in culture
medium. Further addition of methionine had not more positive effect
on MPA production. Finally, results showed that the addition of
acetate to the culture medium had not any observable effect on MPA
production
Abstract: Synthesis gas manufacturing by steam reforming of hydrocarbons is an important industrial process. High endothermic nature of the process makes it one of the most cost and heat intensive processes. In the present work, composite effect of different inert gases on synthesis gas yield, feed gas conversion and temperature distribution along the reactor length has been studied using a heterogeneous model. Mathematical model was developed as a first stage and validated against the existing process models. With the addition of inert gases, a higher yield of synthesis gas is observed. Simultaneously the rector outlet temperature drops to as low as 810 K. It was found that Xenon gives the highest yield and conversion while Helium gives the lowest temperature. Using Xenon inert gas 20 percent reduction in outlet temperature was observed compared to traditional case.
Abstract: The Kinetics formation of labile Complex
Ag (I) tetra (p-carboxyphenyl) porphyrin, was investigated at 25oC
and I=0.1M (NaNO3). By spectrophotometric titration, the
composition ratio of the complex was established to be 2:1
(Ag : H2TCPP). The equilibrium constant, K, was found to be
log 10-6.53. Binding of the first Ag (I) was found to be rate
determining step with rate constant, k1= 4.67×102 . A plausible
mechanism is discussed. We discus theoretically why Ag(I)2TCPP is
unstable.
Abstract: Modeling of a heterogeneous industrial fixed bed
reactor for selective dehydrogenation of heavy paraffin with Pt-Sn-
Al2O3 catalyst has been the subject of current study. By applying
mass balance, momentum balance for appropriate element of reactor
and using pressure drop, rate and deactivation equations, a detailed
model of the reactor has been obtained. Mass balance equations have
been written for five different components. In order to estimate
reactor production by the passage of time, the reactor model which is
a set of partial differential equations, ordinary differential equations
and algebraic equations has been solved numerically.
Paraffins, olefins, dienes, aromatics and hydrogen mole percent as
a function of time and reactor radius have been found by numerical
solution of the model. Results of model have been compared with
industrial reactor data at different operation times. The comparison
successfully confirms validity of proposed model.
Abstract: This study aims to demonstrate the quantification of
peptides based on isotope dilution surface enhanced Raman
scattering (IDSERS). SERS spectra of phenylalanine (Phe), leucine
(Leu) and two peptide sequences TGQIFK (T13) and
YSFLQNPQTSLCFSESIPTPSNR (T6) as part of the 22-kDa
human growth hormone (hGH) were obtained on Ag-nanoparticle
covered substrates. On the basis of the dominant Phe and Leu
vibrational modes, precise partial least squares (PLS) prediction
models were built enabling the determination of unknown T13 and
T6 concentrations. Detection of hGH in its physiological
concentration in order to investigate the possibility of protein
quantification has been achieved.