I
n this study, both experimental and theoretical investigations are performed to obtain new
concrete types with high thermal insulating characteristics for energy-efficient buildings.
In this regard, 102 new concrete wall samples were produced using different aggregates at
different volume fractions, and their thermophysical properties were tested according to EN
and ASTM standards. The experimental research focused on developing new wall or roof
types with higher thermal insulation properties in order to reduce the energy consumption
of buildings due to heating or cooling. In order to specify the thermal performance of developed lightweight concretes, an analytical solution method is developed by the Complex
Finite Fourier Transform (CFFT) method to estimate heat gain utilizing measured thermophysical properties data of those samples. The results indicated that the reduction in heat
gain value was obtained as 83.21 % for the PC100 wall corresponding to conventional concrete. Consequently, the thermal insulation effect of those samples shows excellent potential
for development.
|
In various advanced oxidation processes, photocatalysis is a promising and efficient way? to remove natural organic matter consisting of humic acids and fulvic acids. The princple of this method involves both usage of a semiconductor photocatalyst and O2 for the generation of radicals. Among them, TiO2 photocatalysis is the most popular and studied one
since TiO
2 has unique properties such as being chemically inert, photocatalytically stable,
cheap, non-toxic, environmentally benign and exhibiting high oxidative power. However,
despite all the advantages of using TiO2 as a photocatalyst, there is a major disadvantage.
Since TiO
2 has a broad band gap, its usage widely under solar light is limited and only allows to be active under UV light. Doping is one of the most popular methods to enhance
the photocatalytic activity of TiO2 via using metal or non-metal species as dopants. In
this respect, solar light sensitive TiO2 photocatalyst, C, N, S, Se doped and S/N codoped
TiO
2 photocatalysts were synthesized by using wet-impregnation method. These doped
photocatalysts were characterized by Raman spectroscopy to determine the crystal surface
morphology. Moreover, methylene blue was used to investigate the photocatalytic performance of prepared doped TiO2 photocatalysts in the presence or absence of organic matrix.
Photocatalytic experiments were performed using a solar light simulating photoreactor.
Humic acid characterization was monitored by UV-vis and fluorescence spectroscopy.
|
Alcohols are significant alternative and renewable fuel candidates for the utilization in the internal combustion engines due to encouraging favorable environmental and economic outputs. Long-chain alcohols have various advantages over short-chain alcohols because of
their larger energy content, elevated cetane number (CN) and preferable blending properties,
etc. The objective of the present experimental research deal with the exploring and compare
the influence of the ternary fuel mixtures of petroleum-based diesel fuel, cottonseed oil methyl ester (COME) and long-chain alcohols of isopropanol (Pr), 1-butanol (Bt), and isopentanol (Pt) on the performance and emission characteristics of a single-cylinder, four-stroke,
naturally-aspirated, direct-injection compression-ignition (CI) engine. As the prepared tested fuel samples, four different blends were as follows on a volume basis: B20 (20% COME
+ %80 diesel fuel), B20Pr20 (20% COME + %20 isopropanol + %80 diesel fuel), B20Bt20
(20% COME + %20 1-butanol + %80 diesel fuel), and B20Pt20 (20% COME + %20 isopentanol + %80 diesel fuel). The engine trials were carried out at various loads (0-1250 W)
and under a constant speed (3000 rpm) to observe the aforementioned behaviors. Based on
the experimental outcomes, brake specific fuel consumption (BSFC) values of B20Pr20 exhibited higher than those of other ternary blends at all loads. Brake thermal efficiency (BTE)
values for B20Pt20 were observed as larger than those of ternary blends. B20Pt20 had higher
exhaust gas temperature (EGT) values than those of B20Bt20 and B20Pr20. The infusion of
long-chain alcohols to COME/diesel blend caused to reduce NOX emissions meanwhile isopropanol, 1-butanol, and isopentanol were the most to least influential alcohol types, respectively. Besides, with the addition of alcohol, a substantial decrement was noticed in smoke
opacity at entire loads owing to the excess amount of oxygen content and lesser ratio of C/H
of the alcohols. However, CO and HC emissions rose by infusion of long-chain alcohols to
the blends. Finally, it can be concluded that higher alcohols could be a possible fuel additive
for the fractional replacement for petroleum-based diesel fuel and biodiesel in the blends for
CI engine practices.
INTRODUCTION
Keyword
|
This study was undertaken to determine the controlled rolling and cooling conditions for the production of 20 mm thick American Petroleum Institute (API) X60 and X70 grade steel plates. Nb-Ti microalloyed steel slabs of 200 mm thickness were rolled at four
different finish rolling temperatures (conventional, 950°C, 850°C and 800°C). In some trials, a water table was employed to provide accelerated cooling just after finish rolling. Mechanical tests (tensile, impact and drop weight tear-DWTT) and microstructural examinations were performed on the samples taken from the trial production plates. Fine grained
and essentially ferritic microstructures with strength values satisfying the minimum yield
strength requirement of 415 MPa for the API X60 grade were easily obtained in all rolling
conditions. However, the minimum yield strength requirement of 485 MPa for the API
X70 grade was reached only when accelerated cooling was applied after finish rolling. The
minimum 85% shear fracture required by the DWTT of the API PSL 2 specification could
be met when the finish rolling temperature was lowered or when accelerated cooling was
applied regardless of the finish rolling temperature.
|
The structure and mechanical properties of CoCrFeNi and CoCrFeNiTi0.5Al0.5 (in molar ratio) high entropy alloys were investigated using X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM), hardness and compression tests.
With the addition of Ti and Al, the crystal structure of CoCrFeNi changed from FCC to a
mixture of FCC and double BCC structures. The lattice parameter of FCC increases
upon addition of Al and Ti. The microstructure analysis shows the morphological
transition of dendrites from non-equiaxed to equiaxed during the suction casting of
CoCrFeNiTi
0.5Al 0.5 alloy. The Vickers microhardness testing of CoCr-FeNi alloy reveals
significant increase in hardness with the addition of Al and Ti. The hardness values are
improved in as-suction cast CoCrFeNi and CoCrFeNiTi0.5Al 0.5 alloys compared to their ascast alloys due to strengthening. The CoCrFeNiTi0.5Al 0.5 alloy yields at 1997 MPa and fails
at 2344 MPa. The fracture mechanism of CoCrFeNiTi
0.5Al 0.5 alloy reveals a cleavage mode.
|
I
n this study, the influence of grinding parameters of talc sample in the conventional ball
mill on water-based paint properties was investigated, and the results obtained from the
experiments were statistically modeled. The regression analysis were designed to reveal the
correlation between grinding parameters of the talc and the opacity and brightness of the
paint with the recipes containing prepared mineral. In multivariate regression analysis, the
differential grinding parameters were used to determine the change on opacity and brightness of the paint with a linear model between the change of the grinding parameters as the
variables. Therefore, developed analysis includes a numerical model which could foresee the
changes on final paint properties due to parameter changes (ball charge, material charge and
time) in the grinding process. At the end of the experimental studies, the results indicated
that the changes on brightness and opacity of a water-based paint are very dependant to the
characteristics of talc mineral used as a filler in the same recipe. In other words, it was possible to foresee the changes on opacity and brightness of the paint due to changing grinding
parameters of talc used as mineral filler in paint by using multivariate multiple regression
analysis
|
I
n the present study, the effects of inlet air cooling on compound cycle performance in a
diesel gas turbine engine system where waste heat is used in the composite power system
in the sustainable energy system were investigated thermodynamically. The effects of the
inlet air cooling the system that enhances power production and the resulting thermal efficiency values were analyzed based on various operational variables (gas turbine pressure
ratio, diesel engine compression ratio, gas turbine inlet and fresh air inlet temperatures,
etc.). The energy losses in each system component were determined and the second law
efficiency of the system was determined based on the introduced operational parameters.
The gas turbine unit in the model included a gas generator with two compressors and a
high-pressure turbine, and a low-pressure power turbine running on a separate shaft. The
diesel engine and gas-generator exhaust gases were mixed and expanded in a low-pressure
turbine, leading to the production of power with the waste energy. In the cycle, an intake
air cooler, an intercooler and a recuperative air pre-heater were used. In the intake air cooling cycle, the power increase was around 15% when the pressure rate of the low-pressure
compressor was 3.5. Natural gas was used as fuel in the thermodynamic model. The cycle
irreversibilitywas used in the calculations based onthe thermodynamic concepts
|
I
n concentrated photovoltaic thermal (CPVT) systems, sunlight is directly converted into
electricity and during this conversion waste heat is generated on the photovoltaic module.
The resulting waste heat can be used for heating the fluids. In this study, the effect of using
a low concentrating photovoltaic thermal system as a pre-heater before the evaporator in
the organic Rankine cycle (ORC) was investigated. Thermodynamic analyzes were performed for different solar radiation values, concentration ratio values and various photovoltaic module (PV) materials. The increase in solar radiation and concentration increased
the electricity production in the photovoltaic module and the thermal efficiency of the
system but led to a decrease in exergy efficiency. In the analyzes, four different PV module
materials were examined and M-Si and P-Si module materials showed better performance
in terms of system efficiency and electricity production.
|
This study presents an energy study of an Organic Rankine Cycle (ORC) by comparing
three organic fluids. The latter is considered as a promising cycle for the conversion of
heat into mechanical energy adapted to low-temperature heat sources; it uses more volatile
organic fluids than water, which generally has high molecular weights, thus allowing operating pressures at temperatures lower than those of the traditional Rankine cycle. This study
devoted to the energy analysis of the ORC cycle, taking into account the effect of the operating temperatures and the choice of the organic fluid on the cycle performance. The utilized
three fluids were Toluene, R245fa and R123. The results obtained show that the Toluene
organic fluid has the best energy efficiency of the cycle with 7.45%.
|
VEGF has the positive effect on wound healing. In this study, the effect of VEGF application on some serum parameters during wound healing process were investigated. 36
female normoglycemic Wistar rats were used (200–250 g). Dorsolateral incisional wounds
(length: 4 cm) were made on the two sides of the medulla spinalis in rats. They were divided into 3 groups: untreated group (n=12), chitosan group (n=12) and chitosan+VEGF
group (n=12). The rats were sacrificed on the 3rd and 7th days of post wounding. NOx,
TBARs and RSH levels were determined spectrophotometrically in serum. Results were
compared by one-way ANOVA (p<0.05). Serum TBARs levels both the chitosan treated
group and the VEGF application group was found decreased when compared with untreated groups (3rd and 7th days) (p <0.05). Chitosan and VEGF application were effective
increasing antioxidant capacity of serum on the 7th day. Serum NOx levels decreased in
the VEGF treated groups on 3rd and on 7th days (p<0.05). It can be considered that VEGF
administration has a more positive systemic effect to eliminate increased oxidative damage
in the serum of normoglycemic rats.
|
