Abstract: Regenerative gas turbine engine cycle is presented that yields higher cycle efficiencies than simple cycle operating under the same conditions. The power output, efficiency and specific fuel consumption are simulated with respect to operating conditions. The analytical formulae about the relation to determine the thermal efficiency are derived taking into account the effected operation conditions (ambient temperature, compression ratio, regenerator effectiveness, compressor efficiency, turbine efficiency and turbine inlet temperature). Model calculations for a wide range of parameters are presented, as are comparisons with simple gas turbine cycle. The power output and thermal efficiency are found to be increasing with the regenerative effectiveness, and the compressor and turbine efficiencies. The efficiency increased with increase the compression ratio to 5, then efficiency decreased with increased compression ratio, but in simple cycle the thermal efficiency always increase with increased in compression ratio. The increased in ambient temperature caused decreased thermal efficiency, but the increased in turbine inlet temperature increase thermal efficiency.
Abstract: Two commercial proteases from Bacillus
licheniformis (Alcalase 2.4 L FG and Alcalase 2.5 L, Type DX) were
screened for the production of Z-Ala-Phe-NH2 in batch reaction.
Alcalase 2.4 L FG was the most efficient enzyme for the C-terminal
amidation of Z-Ala-Phe-OMe using ammonium carbamate as
ammonium source. Immobilization of protease has been achieved by
the sol-gel method, using dimethyldimethoxysilane (DMDMOS) and
tetramethoxysilane (TMOS) as precursors (unpublished results). In
batch production, about 95% of Z-Ala-Phe-NH2 was obtained at
30°C after 24 hours of incubation. Reproducibility of different
batches of commercial Alcalase 2.4 L FG preparations was also
investigated by evaluating the amidation activity and the entrapment
yields in the case of immobilization. A packed-bed reactor (0.68 cm
ID, 15.0 cm long) was operated successfully for the continuous
synthesis of peptide amides. The immobilized enzyme retained the
initial activity over 10 cycles of repeated use in continuous reactor at
ambient temperature. At 0.75 mL/min flow rate of the substrate
mixture, the total conversion of Z-Ala-Phe-OMe was achieved after 5
hours of substrate recycling. The product contained about 90%
peptide amide and 10% hydrolysis byproduct.
Abstract: In this article the investigation about installation heat
recovery steam generation (HRSG) on the exhaust of turbo generators of phases 2&3 at South Pars Gas Complex is presented.
The temperature of exhaust gas is approximately 665 degree centigrade, Installation of heat recovery boiler was simulated in
ThermoFlow 17.0.2 software, based on test operation data and the
equipments site operation conditions in Pars exclusive economical energy area, the affect of installation HRSG package on the available
gas turbine and its operation parameters, ambient temperature, the
exhaust temperatures steam flow rate were investigated. Base on the results recommended HRSG package should have the capacity for 98
ton per hour high pressure steam generation this refinery, by use of
exhaust of three gas turbines for each package in operation condition of each refinery at 30 degree centigrade. Besides saving energy this
project will be an Environment-Friendly project. The Payback Period
is estimated approximately 1.8 year, with considering Clean Development Mechanism.
Abstract: Gas turbine systems with wet compression have a
potential for future power generation, since they can offer a high
efficiency and a high specific power with a relatively low cost. In this
study influence of ambient condition on the performance of the wet
compression process is investigated with a non-equilibrium analytical
modeling based on droplet evaporation. Transient behaviors of droplet
diameter and temperature of mixed air are investigated for various
ambient temperatures. Special attention is paid for the effects of
ambient temperature, pressure ratio, and water injection ratios on the
important wet compression variables including compressor outlet
temperature and compression work. Parametric studies show that
downing of the ambient temperature leads to lower compressor outlet
temperature and consequently lower consumption of compression
work even in wet compression processes.
Abstract: This paper presents an experimental investigation of
transformer dielectric response and solid insulation water content.
The dielectric response was carried out on the base of Hybrid
Frequency Dielectric Spectroscopy and Polarization Current
measurements method (FDS &PC). The calculation of the water
content in paper is based on the water content in oil and the obtained
equilibrium curves. A reference measurements were performed at
equilibrium conditions for water content in oil and paper of
transformer at different stable temperatures (25, 50, 60 and 70°C) to
prepare references to evaluate the insulation behavior at the not
equilibrium conditions. Some measurements performed at the
different simulated normal working modes of transformer operation
at the same temperature where the equilibrium conditions. The
obtained results show that when transformer temperature is mach
more than the its ambient temperature, the transformer temperature
decreases immediately after disconnecting the transformer from the
network and this temperature reduction influences the transformer
insulation condition in the measuring process. In addition to the oil
temperature at the near places to the sensors, the temperature
uniformity in transformer which can be changed by a big change in
the load of transformer before the measuring time will influence the
result. The investigations have shown that the extremely influence of
the time between disconnecting the transformer and beginning the
measurements on the results. And the online monitoring for water
content in paper measurements, on the basis of the oil water content
on line monitoring and the obtained equilibrium curves. The
measurements where performed continuously and for about 50 days
without any disconnection in the prepared the adiabatic room.
Abstract: During the last decade ultrafine grained (UFG) and nano-structured (NS) materials have experienced a rapid development. In this research work finite element analysis has been carried out to investigate the plastic strain distribution in equal channel angular process (ECAP). The magnitudes of Standard deviation (S. D.) and inhomogeneity index (Ci) were compared for different ECAP passes. Verification of a three-dimensional finite element model was performed with experimental tests. Finally the mechanical property including impact energy of ultrafine grained pure commercially pure Aluminum produced by severe plastic deformation method has been examined. For this aim, equal channel angular pressing die with the channel angle, outer corner angle and channel diameter of 90°, 20° and 20mm had been designed and manufactured. Commercial pure Aluminum billets were ECAPed up to four passes by route BC at the ambient temperature. The results indicated that there is a great improvement at the hardness measurement, yield strength and ultimate tensile strength after ECAP process. It is found that the magnitudes of HV reach 67HV from 21HV after the final stage of process. Also, about 330% and 285% enhancement at the YS and UTS values have been obtained after the fourth pass as compared to the as-received conditions, respectively. On the other hand, the elongation to failure and impact energy have been reduced by 23% and 50% after imposing four passes of ECAP process, respectively.
Abstract: Experiments have been carried out at the Latvia
University of Agriculture Department of Food Technology. The aim
of this work was to assess the effect of thermal treatment in flexible
retort pouch packaging on the quality of potatoes’ produce during the
storage time. Samples were evaluated immediately after retort
thermal treatment; and following 1; 2; 3 and 4 storage months at the
ambient temperature of +18±2ºC in vacuum packaging from
polyamide/polyethylene (PA/PE) and aluminum/polyethylene
(Al/PE) film pouches with barrier properties. Experimentally the
quality of the potatoes’ produce in dry butter and mushroom
dressings was characterized by measuring pH, hardness, color,
microbiological properties and sensory evaluation. The sterilization
was effective in protecting the produce from physical, chemical, and
microbial quality degradation. According to the study of obtained
data, it can be argued that the selected product processing technology
and packaging materials could be applied to provide the safety and
security during four-month storage period.
Abstract: Various solar energy technologies exist and they have
different application techniques in the generation of electrical power.
The widespread use of photovoltaic (PV) modules in such
technologies has been limited by relatively high costs and low
efficiencies. The efficiency of PV panels decreases as the operating
temperatures increase. This is due to the affect of solar intensity and
ambient temperature. In this work, Computational Fluid Dynamics
(CFD) was used to model the heat transfer from a standard PV panel
and thus determine the rate of dissipation of heat. To accurately
model the specific climatic conditions of the United Arab Emirates
(UAE), a case study of a new build green building in Dubai was
used. A finned heat pipe arrangement is proposed and analyzed to
determine the improved heat dissipation and thus improved
performance efficiency of the PV panel. A prototype of the
arrangement is built for experimental testing to validate the CFD
modeling and proof of concept.
Abstract: The counter flow solar air heaters, with four
transverse fins and wire mesh layers are constructed and investigated
experimentally for thermal efficiency at a geographic location of
Cyprus in the city of Famagusta. The absorber plate is replaced by
sixteen steel wire mesh layers, 0.18 x 0.18cm in cross section
opening and a 0.02cm in diameter. The wire mesh layers arranged in
three groups, first and second include 6 layers, while the third include
4 layers. All layers fixed in the duct parallel to the glazing and each
group separated from the others by wood frame thickness of 0.5cm to
reduce the pressure drop. The transverse fins arranged in a way to
force the air to flow through the bed like eight letter path with flow
depth 3cm. The proposed design has increased the heat transfer rate,
but on other hand causes a high pressure drop. The obtained results
show that, for air mass flow rate range between 0.011-0.036kg/s, the
thermal efficiency increases with increasing the air mass flow. The
maximum efficiency obtained is 65.6% for the mass flow rate of
0.036kg/s. Moreover, the temperature difference between the outlet
flow and the ambient temperature, ΔT, reduces as the air mass flow
rate increase. The maximum difference between the outlet and
ambient temperature obtained was 43°C for double pass for minimum
mass flow rate of 0.011kg/s. Comparison with a conventional solar
air heater collector shows a significantly development in the thermal
efficiency.
Abstract: Biogas, a clean renewable energy, is attracting a growing
concern of researchers and professionals in many fields. Based
on the natural and climatic conditions in semi-arid regions of northwestern
China, the present study introduces a specifically-designed
family-size biogas plant (with a digester of 10m3) with manure
and urine of animals and humanity as raw materials. The biogas
plant is applicable to areas with altitudes of more than 2000 meters
in northwestern China. In addition to the installation cost, a little
operational expenditure, structure, characteristics, benefits of this
small-scale biogas plant, this article introduces a wide range of
specific popularization methods such as training, financial support,
guided tour to the biogas plant, community-based group study and
delivery of operational manuals. The feasibility of the biogas plant is
explored on the basis of the availability of the raw materials. Simple
operations contained in the current work increase the possibility of
the wide use of this small-scale biogas plant in similar regions of the
world.
Abstract: The work presented in this study is related to an
energy system analysis based on passive cooling system for
dwellings. It consists to solar chimney energy performances
determination versus geometrical and environmental considerations
as the size and inlet width conditions of the chimney. Adrar site
located in the southern region of Algeria is chosen for this study
according to ambient temperature and solar irradiance technical data
availability. Obtained results are related to the glazing temperature
distributions, the chimney air flow and internal wall temperatures.
The air room change per hour (ACH) parameter, the outlet air
velocity and mass air flow rate are also determined. It is shown that
the chimney width has a significant effect on energy performances
compared to its entry size. A good agreement is observed between
these results and those obtained by others from the literature.
Abstract: This paper considers the effect of heat generation
proportional l to (T - T∞ )p , where T is the local temperature and T∞
is the ambient temperature, in unsteady free convection flow near the
stagnation point region of a three-dimensional body. The fluid is
considered in an ambient fluid under the assumption of a step change
in the surface temperature of the body. The non-linear coupled partial
differential equations governing the free convection flow are solved
numerically using an implicit finite-difference method for different
values of the governing parameters entering these equations. The
results for the flow and heat characteristics when p ≤ 2 show that
the transition from the initial unsteady-state flow to the final steadystate
flow takes place smoothly. The behavior of the flow is seen
strongly depend on the exponent p.
Abstract: In this paper a three dimensional thermal model of a
sliding contact system is proposed for both steady-state or transient
conditions. The influence of contact force, electric current and
ambient temperature on the temperature distribution, has been
investigated. A thermal analysis of the different type of the graphite
material of fixed electric contact and its influence on contact system
temperature rise, has been performed. To validate the three
dimensional thermal model, some experimental tests have been done.
There is a good correlation between experimental and simulation
results.
Abstract: The mechanism behind the electromigration and
thermomigration failure in flip-chip solder joints with Cu-pillar bumps
was investigated in this paper through using finite element method.
Hot spot and the current crowding occurrs in the upper corner of
copper column instead of solders of the common solder ball. The
simulation results show that the change in thermal gradient is
noticeable, which might greatly affect the reliability of solder joints
with Cu-pillar bumps under current stressing. When the average
applied current density is increased from 1×104 A/cm2 to 3×104 A/cm2
in solders, the thermal gradient would increase from 74 K/cm to 901
K/cm at an ambient temperature of 25°C. The force from thermal
gradient of 901 K/cm can nearly induce thermomigration by itself.
With the increase in applied current, the thermal gradient is growing. It
is proposed that thermomigration likely causes a serious reliability
issue for Cu column based interconnects.
Abstract: In the current study, we have conducted an experimental investigation on the utilization of electronic arc furnace (EAF) reducing slag for the absorption of CO2 via wet grinding method. It was carried out by various grinding conditions. The slag was ground in the vibrating ball mill in the presence of CO2 and pure water under ambient temperature. The reaction behavior was monitored with constant pressure method, and the changes of experimental systems volume as a function of grinding time were measured. It was found that the CO2 absorption occurred as soon as the grinding started. The CO2 absorption was significantly increased in the case of wet grinding compare to the dry grinding. Generally, the amount of CO2 absorption increased as the amount of water, weight of slag and initial pressure increased. However, it was decreased when the amount of water exceeds 200ml and when smaller balls were used. The absorption of CO2 occurred simultaneously with the start of the grinding and it stopped when the grinding was stopped. According to this research, the CO2 reacted with the CaO inside the slag, forming CaCO3.
Abstract: Temperature rise in a transformer depends on variety
of parameters such as ambient temperature, output current and type
of the core. Considering these parameters, temperature rise estimation
is still complicated procedure. In this paper, we present a new model
based on simple electrical equivalent circuit. This method avoids the
complication associated to accurate estimation and is in very good
agreement with practice.
Abstract: The increase in energy demand has raised concerns
over adverse impacts on the environment from energy generation. It
is important to understand the status of energy consumption for
institutions such as Curtin Sarawak to ensure the sustainability of
energy usage, and also to reduce its costs. In this study, a preliminary
audit framework was developed and was conducted around the
Malaysian campus to obtain information such as the number and
specifications of electrical appliances, built-up area and ambient
temperature to understand the relationship of these factors with
energy consumption. It was found that the number and types of
electrical appliances, population and activities in the campus
impacted the energy consumption of Curtin Sarawak directly.
However, the built-up area and ambient temperature showed no clear
correlation with energy consumption. An investigation of the diurnal
and seasonal energy consumption of the campus was also carried out.
From the data, recommendations were made to improve the energy
efficiency of the campus.
Abstract: In this paper, the data correction algorithm is suggested
when the environmental air temperature varies. To correct the infrared
data in this paper, the initial temperature or the initial infrared image
data is used so that a target source system may not be necessary. The
temperature data obtained from infrared detector show nonlinear
property depending on the surface temperature. In order to handle this
nonlinear property, Taylor series approach is adopted. It is shown that
the proposed algorithm can reduce the influence of environmental
temperature on the components in the board. The main advantage of
this algorithm is to use only the initial temperature of the components
on the board rather than using other reference device such as black
body sources in order to get reference temperatures.
Abstract: Solid dispersions (SD) of curcuminpolyvinylpyrrolidone
in the ratio of 1:2, 1:4, 1:5, 1:6, and 1:8 were
prepared in an attempt to increase the solubility and dissolution.
Solubility, dissolution, powder X-ray diffraction (XRD), differential
scanning calorimetry (DSC) and Fourier transform infrared
spectroscopy (FTIR) of solid dispersions, physical mixtures (PM)
and curcumin were evaluated. Both solubility and dissolution of
curcumin solid dispersions were significantly greater than those
observed for physical mixtures and intact curcumin. The powder
X-ray diffractograms indicated that the amorphous curcumin was
obtained from all solid dispersions. It was found that the optimum
weight ratio for curcumin:PVP K-30 is 1:6. The 1:6 solid dispersion
still in the amorphous from after storage at ambient temperature for 2
years and the dissolution profile did not significantly different from
freshly prepared.
Abstract: Gas turbine air inlet cooling is a useful method for
increasing output for regions where significant power demand and
highest electricity prices occur during the warm months. Inlet air
cooling increases the power output by taking advantage of the gas
turbine-s feature of higher mass flow rate when the compressor inlet
temperature decreases. Different methods are available for reducing
gas turbine inlet temperature. There are two basic systems currently
available for inlet cooling. The first and most cost-effective system is
evaporative cooling. Evaporative coolers make use of the evaporation
of water to reduce the gas turbine-s inlet air temperature. The second
system employs various ways to chill the inlet air. In this method, the
cooling medium flows through a heat exchanger located in the inlet
duct to remove heat from the inlet air. However, the evaporative
cooling is limited by wet-bulb temperature while the chilling can cool
the inlet air to temperatures that are lower than the wet bulb
temperature. In the present work, a thermodynamic model of a gas
turbine is built to calculate heat rate, power output and thermal
efficiency at different inlet air temperature conditions. Computational
results are compared with ISO conditions herein called "base-case".
Therefore, the two cooling methods are implemented and solved for
different inlet conditions (inlet temperature and relative humidity).
Evaporative cooler and absorption chiller systems results show that
when the ambient temperature is extremely high with low relative
humidity (requiring a large temperature reduction) the chiller is the
more suitable cooling solution. The net increment in the power output
as a function of the temperature decrease for each cooling method is
also obtained.