Search results for: Chevron corrugated plate heat exchanger

Authors: W. Sun, W. Wen, J. Lu, A. A. Becker

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In this work, methods for determining creep properties which can be used to represent the full life until failure from miniature specimen creep tests based on analytical solutions are presented. Examples used to demonstrate the application of the methods include a miniature rectangular thin beam specimen creep test under three-point bending and a miniature two-material tensile specimen creep test subjected to a steady load. Mathematical expressions for deflection and creep strain rate of the two specimens were presented for the Kachanov-Rabotnov creep damage model. On this basis, an inverse procedure was developed which has potential applications for deriving the full life creep damage constitutive properties from a very small volume of material, in particular, for various microstructure constitutive  regions, e.g. within heat-affected zones of power plant pipe weldments. Further work on validation and improvement of the method is addressed.

Keywords: creep damage property, miniature specimen, inverse approach, finite element modeling

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Authors: Elmo Thiao Lins Cöuras Ford, Valentina Alessandra Carvalho do Vale, R. M. Nascimento, J. U. L. Mendes

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Now the great majority of the applications of thermal isolation in the strip of drops and averages temperatures (up to 200ºC), it is made being used from aggressive materials to the nature such an as: glass wool, rock wool, polystyrene, EPS among others. Such materials, in spite of the effectiveness in the retention of the flow of heat, possess considerable cost and when discarded they are long years to be to decompose. In that context, trying to adapt the world politics the about of the preservation of the environment, a study began with intention of developing a material composite, with properties of thermal, originating from insulating industrial residues. In this research, the behavior of the composite was analyzed, as submitted the fire. For this, the reaction rehearsals were accomplished to the fire for the composites 2:1; 1:1; 1:2 and for the latex, based in the "con" experiment in agreement with the norm ASTM–E 1334-90. As consequence, in function of the answers of the system, was possible to observe to the acting of each mixture proportion.

Keywords: composite, Latex, reacion to the fire, thermal isolation

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Authors: Muhammad Khairul Anuar Mohamed, Mohd Zuki Salleh, Anuar Ishak, Nor Aida Zuraimi Md Noar

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In this study, the numerical investigation of viscous dissipation on convective boundary layer flow towards a horizontal circular cylinder with constant wall temperature is considered. The transformed partial differential equations are solved numerically by using an implicit finite-difference scheme known as the Keller-box method. Numerical solutions are obtained for the reduced Nusselt number and the skin friction coefficient as well as the velocity and temperature profiles. The features of the flow and heat transfer characteristics for various values of the Prandtl number and Eckert number are analyzed and discussed. The results in this paper is original and important for the researchers working in the area of boundary layer flow and this can be used as reference and also as complement comparison purpose in future.

Keywords: free convection, horizontal circular cylinder, viscous dissipation, convective boundary layer flow

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Authors: N. H. S. Mustafa, N. M. Yatim

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Thermoelectric materials arrange in segmented design could increase the conversion of heat to electricity performance. This is due to the properties of materials that perform peak at narrow temperature range. Performance of the materials determines by dimensionless figure-of-merit, ZT which consist of thermoelectric properties namely Seebeck coefficient, electrical resistivity, and thermal conductivity. Since different materials were arrange in segmented, determination of ZT cannot be measured using the conventional approach. Therefore, this research used 'open-short circuit' technique to measure the segmented performance. Segmented thermoelectric materials consist of bismuth telluride, and lead telluride was segmented together under cold press technique. The results show thermoelectric properties measured is comparable with calculated based on commercially available of individual material. Performances of segmented sample under different polarity also indicate dependability of material with position and temperature. Segmented materials successfully measured under real condition and optimization of the segmented can be designed from the study of polarity change.

Keywords: thermoelectric, segmented, ZT, polarity, performance

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Authors: Sunday Odunaiya

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The statistics of banks in operation in this current dispensation compared to some decades ago has brought about a lot of changes on the face of the financial system. The demand of customers, technological advancement, and government policies among others has therefore generated a lot of heat for financial sector’s growth, sustenance and survival. This paper discusses mergers and acquisitions (M&A) in banking sector using West Africa as a yardstick of evaluation. It explains rigorously the conditions that warrant mergers and acquisitions in the banking sector, its effect, and how to ensure mergers and acquisitions effectiveness in the banking sector. The conceptual and empirical review of the relevant literature were done systematically while value-increasing and value-decreasing theories were used to substantiate the discourse. Findings of this paper show that mergers and acquisitions is a practical and conscious activity in Nigeria, Ghana and Ivory Coast from earliest time till date with tremendous turnaround in the financial sector. It was found out that M&A is consensually arrived at by the targets and the acquirer on a value-based account. In other words, merger and acquisition is a deliberate decision reached by the management of such bank for a ‘just cause’.

Keywords: acquisitions, merger, management, financial sector

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Authors: Antonis Constantinides, Christos Yiallouras, Christakis Damianou

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The application of today's semiconductor transistors in high power UHF DVB-T linear amplifiers has evolved significantly by utilizing LDMOS technology. This fact provides engineers with the option to design a single transistor signal amplifier which enables output power and linearity that was unobtainable previously using bipolar junction transistors or later type first generation MOSFETS. The quiescent current stability in terms of thermal variations of the LDMOS guarantees a robust operation in any topology of DVB-T signal amplifiers. Otherwise, progressively uncontrolled heat dissipation enhancement on the LDMOS case can degrade the amplifier’s crucial parameters in regards to the gain, linearity, and RF stability, resulting in dysfunctional operation or a total destruction of the unit. This paper presents one more sophisticated approach from the traditional biasing circuits used so far in LDMOS DVB-T amplifiers. It utilizes a microprocessor control technology, providing stability in topologies where IDQ must be perfectly accurate.

Keywords: LDMOS, amplifier, back-off, bias circuit

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Authors: Phanindra Prasad Thummala, Umran Tezcan Un, Ahmet Ozan Celik

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Removal of CO₂ by MEA (monoethanolamine) in structured packing columns depends highly on the gas-liquid interfacial area and film thickness (liquid load). CFD (computational fluid dynamics) is used to find the interfacial area, film thickness and their impact on mass transfer in gas-liquid flow effectively in any column geometry. In general modeling approaches used in CFD derive mass transfer parameters from standard correlations based on penetration or surface renewal theories. In order to avoid the effect of assumptions involved in deriving the correlations and model the mass transfer based solely on fluid properties, state of art approaches like one fluid formulation is useful. In this work, the one fluid formulation was implemented and evaluated for modeling the physical mass transfer of CO₂ by N₂O analogy in OpenFOAM CFD software. N₂O analogy avoids the effect of chemical reactions on absorption and allows studying the amount of CO₂ physical mass transfer possible in a given geometry. The computational domain in the current study was a flat plate with gas and liquid flowing in the countercurrent direction. The effect of operating parameters such as flow rate, the concentration of MEA and angle of inclination on the physical mass transfer is studied in detail. Liquid side mass transfer coefficients obtained by simulations are compared to the correlations available in the literature and it was found that the one fluid formulation was effectively capturing the effects of interface surface instabilities on mass transfer coefficient with higher accuracy. The high mesh refinement near the interface region was found as a limiting reason for utilizing this approach on large-scale simulations. Overall, the one fluid formulation is found more promising for CFD studies involving the CO₂ mass transfer.

Keywords: one fluid formulation, CO₂ absorption, liquid mass transfer coefficient, OpenFOAM, N₂O analogy

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Authors: Ammar Alali, Mahmoud Abughaban, William Contreras Otalvora

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Optimizing the drilling process for cost and efficiency requires the optimization of the rate of penetration (ROP). ROP is the measurement of the speed at which the wellbore is created, in units of feet per hour. It is the primary indicator of measuring drilling efficiency. Maximization of the ROP can indicate fast and cost-efficient drilling operations; however, high ROPs may induce unintended events, which may lead to nonproductive time (NPT) and higher net costs. The proposed ROP optimization solution is a hybrid, data-driven system that aims to improve the drilling process, maximize the ROP, and minimize NPT. The system consists of two phases: (1) utilizing existing geological and drilling data to train the model prior, and (2) real-time adjustments of the controllable dynamic drilling parameters [weight on bit (WOB), rotary speed (RPM), and pump flow rate (GPM)] that direct influence on the ROP. During the first phase of the system, geological and historical drilling data are aggregated. After, the top-rated wells, as a function of high instance ROP, are distinguished. Those wells are filtered based on NPT incidents, and a cross-plot is generated for the controllable dynamic drilling parameters per ROP value. Subsequently, the parameter values (WOB, GPM, RPM) are calculated as a conditioned mean based on physical distance, following Inverse Distance Weighting (IDW) interpolation methodology. The first phase is concluded by producing a model of drilling best practices from the offset wells, prioritizing the optimum ROP value. This phase is performed before the commencing of drilling. Starting with the model produced in phase one, the second phase runs an automated drill-off test, delivering live adjustments in real-time. Those adjustments are made by directing the driller to deviate two of the controllable parameters (WOB and RPM) by a small percentage (0-5%), following the Constrained Random Search (CRS) methodology. These minor incremental variations will reveal new drilling conditions, not explored before through offset wells. The data is then consolidated into a heat-map, as a function of ROP. A more optimum ROP performance is identified through the heat-map and amended in the model. The validation process involved the selection of a planned well in an onshore oil field with hundreds of offset wells. The first phase model was built by utilizing the data points from the top-performing historical wells (20 wells). The model allows drillers to enhance decision-making by leveraging existing data and blending it with live data in real-time. An empirical relationship between controllable dynamic parameters and ROP was derived using Artificial Neural Networks (ANN). The adjustments resulted in improved ROP efficiency by over 20%, translating to at least 10% saving in drilling costs. The novelty of the proposed system lays is its ability to integrate historical data, calibrate based geological formations, and run real-time global optimization through CRS. Those factors position the system to work for any newly drilled well in a developing field event.

Keywords: drilling optimization, geological formations, machine learning, rate of penetration

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Authors: Gamal Alamri, Tariq Iqbal

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This paper presents an optimum designs and thermal analysis of concrete house in the hot climate of Libya. For this goal we have used BEopt software (building energy optimization) that provides capabilities for estimating residential building design and thermal analysis. The most area of the house that is exposed to the sunlight’s is the roof leading to heat gain. Therefore, house cooling consumes high energy. The cooling energy consumption is three times the heating energy consumption. In order to maintain comfortable indoor conditions in a low-energy house, the entire building envelope needs to be perfectly insulated and prevented from air leakages. Insulated roof is selected to reduce cooling demand, and the paper presents details and BEopt simulation results. Designed house needs 12.02mmbtus/year. Furthermore, the modeling indicates that the designed house is close to achieving the Passive standard.

Keywords: concrete house design, thermal analysis, hot climate, BEopt software

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Authors: A. Saha Chaudhuri, D. Sarkar

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In steel construction, there are two families of structural members. One is hot rolled steel and another is cold formed steel. Cold formed steel section includes steel sheet, strip, plate or flat bar. Cold formed steel section is manufactured in roll forming machine by press brake or bending operation. Cold formed steel (CFS), also known as Light Gauge Steel (LGS). As cold formed steel is a sustainable material, it is widely used in green building. Cold formed steel can be recycled and reused with no degradation in structural properties. Cold formed steel structures can earn credits for green building ratings such as LEED and similar programs. Cold formed steel construction satisfies international demand for better, more efficient and affordable buildings. Cold formed steel sections are used in building, car body, railway coach, various types of equipment, storage rack, grain bin, highway product, transmission tower, transmission pole, drainage facility, bridge construction etc. Various shapes of cold formed steel sections are available, such as C section, Z section, I section, T section, angle section, hat section, box section, square hollow section (SHS), rectangular hollow section (RHS), circular hollow section (CHS) etc. In building construction cold formed steel is used as eave strut, purlin, girt, stud, header, floor joist, brace, diaphragm and covering for roof, wall and floor. Cold formed steel has high strength to weight ratio and high stiffness. Cold formed steel is non shrinking and non creeping at ambient temperature, it is termite proof and rot proof. CFS is durable, dimensionally stable and non combustible material. CFS is economical in transportation and handling. At present days cold formed steel becomes a competitive building material. In this paper all these applications related present research work are described and how the CFS can be used as blast resistant structural system that is examined.

Keywords: cold form steel sections, applications, present research review, blast resistant design

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Authors: Kubra Sultan Yuzuncuyil, Aytekin İsman, Berkay Bulus

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With the developments of information and communication technologies, the forms of molding public opinion have changed. In the presence of Internet, the notion of activism has been endowed with digital codes. Activists have engaged the use of Internet into their campaigns and the process of creating collective identity. Activist movements have been incorporating the relevance of new communication technologies for their goals and opposition. Creating and managing activism through Internet is called Online Activism. In this main, Slow Food Movement which was emerged within the philosophy of defending regional, fair and sustainable food has been engaging Internet into their activist campaign. This movement supports the idea that a new food system which allows strong connections between plate and planet is possible. In order to make their voices heard, it has utilized social networks and develop particular skills in the framework online activism. This study analyzes online activist skills of Slow Food Movement (SFM) develop and attempts to measure its effectiveness. To achieve this aim, it adopts the model proposed by Sivitandies and Shah and conduct both qualitiative and quantiative content analysis on social network use of Slow Food Movement. In this regard, the sample is chosen as the official profile and analyzed between in a three month period respectively March-May 2017. It was found that SFM develops particular techniques that appeal to the model of Sivitandies and Shah. The prominent skill in this regard was found as hyperlink abbreviation and use of multimedia elements. On the other hand, there are inadequacies in hashtag and interactivity use. The importance of this study is that it highlights and discusses how online activism can be engaged into a social movement. It also reveals current online activism skills of SFM and their effectiveness. Furthermore, it makes suggestions to enhance the related abilities and strengthen its voice on social networks.

Keywords: slow food movement, Twitter, internet, online activism

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Authors: Igor Svishchev, Kashif Choudhry

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Progress in advanced energy technologies is not feasible without understanding how engineering materials perform under extreme environmental conditions. The corrosion behaviour of Fe-Ni-Cr and Zr alloys has been systematically examined under high-temperature and supercritical water flow conditions. The changes in elemental release rate and dissolved gas concentration provide valuable insights into the mechanism of passivation by forming oxide films. A non-intrusive method for monitoring the extent of surface oxidation based on hydrogen release rate has been developed. This approach can be used for the on-line monitoring corrosion behavior of reactor materials without the need to interrupt the flow and remove corrosion coupons. Surface catalysed thermochemical reactions may generate sufficient hydrogen to have an effect on the accumulation of oxidizing species generated by radiolytic processes in the heat transport systems of the supercritical water cooled nuclear reactor.

Keywords: high-temperature corrosion, non-intrusive monitoring, reactor materials, supercritical water

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Authors: J. Pantoja Enríquez, G. P. Hernández, G. I. Duharte, X. Mathew, J. Moreira, P. J. Sebastian

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Cadmium sulfide films were deposited onto glass substrates by chemical bath deposition (CBD) from a bath containing cadmium acetate, ammonium acetate, thiourea, and ammonium hydroxide. The CdS thin films were annealed in air, argon, hydrogen and nitrogen for 1 h at various temperatures (300, 350, 400, 450 and 500 °C). The changes in optical and electrical properties of annealed treated CdS thin films were analyzed. The results showed that, the band-gap and resistivity depend on the post-deposition annealing atmosphere and temperatures. Thus, it was found that these properties of the films, were found to be affected by various processes with opposite effects, some beneficial and others unfavorable. The energy gap and resistivity for different annealing atmospheres was seen to oscillate by thermal annealing. Recrystallization, oxidation, surface passivation, sublimation and materials evaporation were found the main factors of the heat-treatment process responsible for this oscillating behavior. Annealing over 400 °C was seen to degrade the optical and electrical properties of the film.

Keywords: cds, thin films, annealing, optical, electrical properties

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Authors: F. R. M. Nascimento, E. E. S. Lora, J. C. E. Palácio

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A mathematical model to investigate the performance of a two stage fixed bed downdraft gasifier operating with air, steam and oxygen mixtures as the gasifying fluid has been developed. The various conditions of mixtures for a double stage fluid entry, have been performed. The model has been validated through a series of experimental tests performed by NEST – The Excellence Group in Thermal and Distributed Generation of the Federal University of Itajubá. Influence of mixtures are analyzed through the Steam to Biomass (SB), Equivalence Ratio (ER) and the Oxygen Concentration (OP) parameters in order to predict the best operating conditions to obtain adequate output gas quality, once is a key parameter for subsequent gas processing in the synthesis of biofuels, heat and electricity generation. Results show that there is an optimal combination in the steam and oxygen content of the gasifying fluid which allows the user find the best conditions to design and operate the equipment according to the desired application.

Keywords: air, equilibrium, downdraft, fixed bed gasification, mathematical modeling, mixtures, oxygen steam

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Authors: Mahmoud M. Tash, S. Alkahtani

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The present study was undertaken to investigate the effect of pre-aging and aging parameters (time and temperature) on the mechanical properties of Al-Mg-Zn (7075) alloys. Ultimate tensile strength, 0.5% offset yield strength and % elongation measurements were carried out on specimens prepared from cast and heat treated 7075 alloys. Aging treatments were carried out for the as solution treated (SHT) specimens (after quenching in warm water). The specimens were aged at different conditions; Natural aging was carried out at room temperature for different periods of time. Double aging was performed for SHT conditions (pre-aged at different time and temperature followed by high temperature aging). Ultimate tensile strength, yield strength and % elongation as a function of different pre-aging and aging parameters are analysed to acquire an understanding of the effects of these variables and their interactions on the mechanical properties of Be-treated 7075 alloys.

Keywords: duplex aging treatment, mechanical properties, Al-Mg-Zn (7075) alloys, manufacturing

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Authors: Sachin Mahajan, Ghizal Ansari

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TeO2-WO3-Li2O glass doped erbium ions (1mol %) and embedded silver nanoparticles( Ag NPs) has successfully been prepared by melt quenching technique and increasing the heat-treatment duration. The amorphous nature of the glass is determined by X-ray diffraction method, and the presences of silver nanoparticles are confirmed using Transmission Electron Microscopy analysis. TEM image reveals that the Ag NPs are dispersed homogeneously with average size 18 nm. From the UV-Vis absorption spectra, the surface plasmon resonance (SPR) peaks are detected at 550 and 578 nm. Under 980 nm excitation wavelengths, enhancement of red upconversion fluorescence and near-infrared broadband emission around 1550nm of Er3+ ions doped tellurite glasses containing Ag NPs have been observed. The observed enhancement of Er3+ emission is mainly attributed to the local field effects of Ag NPs causes an intensified electromagnetic field around NPs. For observed enhancement involved mechanisms are discussed.

Keywords: erbium ions, silver nanoparticle, surface plasmon resonance, upconversion emission

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Authors: Syahrir Andi Mangga, Ipranta

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The geological, paleomagnetic, geochemical and geophysical Investigation in The Sumatra Region has yielded some new data, has stimulated a reassessment of stratigraphy, structure, tectonic evolution and which can show a Sumatra geodynamic model. Sumatra island has in the margin of southwest part of the Eurasia plate in the Sundaland cratonic block and occurred as the amalgamation of allochtonous microplates, continental fragments, Island arc and accrctionary by foreland complex which assembled prior to Tertiary. The allochtonous rocks (terranes), can be divided into 4 (four) Terranes with Paleozoic to Mesosoic in age, had different origin, lithology and are separated by a Suture as main fault with trending NW-SE. The terranes are: the Tigapuluh-Bohorok (East Sumatra block / Sibumasu block), Permo-Carboniferous in age and is characterized by the rock types formed in glacio-marine and was intruded by Late Triassic to Early Jurrasic granitics, occupied in the Eastern part of Sumatra, the paleomagnetic data shown 41° South. Tanjung Karang - Gunung Kasih Terrane, is composed of higher metamorphic rocks and supposed to be pre-Carboniferous in age, covered by Mesozoic sedimentary rocks and were intruded by granitic-dioritic rocks, occupied in the Southern part of Sumatra, the paleomagnetic data shown 19° North. The Kuantan-Duabelas Mountain (West Sumatra block) is occupied by metamorphic, sedimentary and volcanic rocks of Paleozoic - Mesozoic (Carboniferous - Triassic) in age, contains a Cathaysion fauna and flora and are intruded by the Mesozoic granitoid rocks. The terrane occurred in the western part of Sumatra. Meanwhile, the Gumai-Garba (Waloya Terrane) which is occupied by the tectonite/melange, metasediment, carbonate and volcanic rocks of Mesozoic (Jurassic - Cretaceous) in age, are intruted by the Late Cretaceous granitoid rocks, the paleomagnetic data shown 30° - 31° South.

Keywords: tectonostratigraphy, amalgamation, allochtonous, terranes, sumatra

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Authors: Murada Alholy, Mengshi Lin, Omar Alhaj, Mahmoud Abugoush

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Alicyclobacillus is a causative agent of spoilage in pasteurized and heat-treated apple juice products. Differentiating between this genus and the closely related Bacillus is crucially important. In this study, Fourier transform infrared spectroscopy (FT-IR) was used to identify and discriminate between four Alicyclobacillus strains and four Bacillus isolates inoculated individually into apple juice. Loading plots over the range of 1350 and 1700 cm-1 reflected the most distinctive biochemical features of Bacillus and Alicyclobacillus. Multivariate statistical methods (e.g. principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA)) were used to analyze the spectral data. Distinctive separation of spectral samples was observed. This study demonstrates that FT-IR spectroscopy in combination with multivariate analysis could serve as a rapid and effective tool for fruit juice industry to differentiate between Bacillus and Alicyclobacillus and to distinguish between species belonging to these two genera.

Keywords: alicyclobacillus, bacillus, FT-IR, spectroscopy, PCA

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Authors: Navpreet Kaur, Randhir Singh

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Diabetic neuropathy is one of the most common microvascular complications of diabetes mellitus which affects more than 50% of diabetic patients. The present study targeted oxidative stress mediated nerve damage in diabetic rats using a hydro-alcohol extract of Cucurbita pepo L. (Family: Cucurbitaceae) and its potential in treatment of diabetic neuropathy. Diabetes neuropathy was induced in Wistar rats by injection of streptozotocin (65 mg/kg, i.p.) 15 min after Nicotinamide (230 mg/kg, i.p.) administration. Hydro-alcohol extract of C. pepo seeds was assessed by oral administration at 100, 200 and 400 mg/kg in STZ-nicotinamide induced diabetic rats. Thermal hyperalgesia (Eddy's hot plate and tail immersion), mechanical hyperalgesia (Randall-Selitto) and tactile allodynia (Von Frey hair tests) were evaluated in all groups of streptozotocin diabetic rats to assess the extent of neuropathy. Tissue (sciatic nerve) antioxidant enzymes (SOD, CAT, GSH and LPO) levels were measured along with the formation of AGEs in serum to assess the effect of hydro-alcohol extract of C. pepo in ameliorating oxidative stress. Diabetic rats exhibited significantly decreased tail-flick latency in the tail-immersion test and decreased paw withdrawal threshold in both Randall-Selitto and von-Frey hair test. A decrease in the nociceptive threshold was accompanied by significantly increased oxidative stress in sciatic nerve of diabetic rats. Treatment with the C. pepo hydro-alcohol extract significantly attenuated all the behavioral and biochemical alterations in a dose-dependent manner. C. pepo attenuated the diabetic condition and also reversed neuropathic pain through modulation of oxidative stress and thus it may find application as a possible therapeutic agent against diabetic neuropathy.

Keywords: advanced glycation end products, antioxidant enzymes, cucurbita pepo, hyperglycemia

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Authors: Haibo Sheng, Yuan Hu

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Spinel structure Zinc stannate (Zn2SnO4, ZS)/Graphene was successfully synthesized by a simple in situ hydrothermal route. Morphological study and structure analysis confirmed the homogenously loading of ZS on the graphene sheets. Then, the resulted ZS/graphene hybrids were incorporated into epoxy resin to form EP/ZS/graphene composites by a solvent dispersion method. Improved thermal stability was investigated by Thermogravimetric Analysis (TGA). Cone calorimeter result showed low peak heat release rate (PHRR). Toxical gases release during combustion was evaluated by a facile device organized in our lab. The results showed that the release of NOx, HCN decrease of about 55%. Also, TG-IR technology was used to investigate the gas release during the EP decomposition process. The CO release had decreased about 80%.The EP/G/ZS showed lowest hazards during combustion (including flame retardancy, thermal stability, lower toxical gases release and so on) than pure EP.

Keywords: fire hazards, zinc stannate, epoxy resin, toxical gas hazards

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Authors: Rhoda Afriyie Mensah, Lin Jiang, Solomon Asante-Okyere, Xu Qiang, Cong Jin

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Flammability analysis of extruded polystyrene (XPS) has become crucial due to its utilization as insulation material for energy efficient buildings. Using the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods, the degradation kinetics of two pure XPS from the local market, red and grey ones, were obtained from the results of thermogravity analysis (TG) and microscale combustion calorimetry (MCC) experiments performed under the same heating rates. From the experiments, it was discovered that red XPS released more heat than grey XPS and both materials showed two mass loss stages. Consequently, the kinetic parameters for red XPS were higher than grey XPS. A comparative evaluation of activation energies from MCC and TG showed an insignificant degree of deviation signifying an equivalent apparent activation energy from both methods. However, different activation energy profiles as a result of the different chemical pathways were presented when the dependencies of the activation energies on extent of conversion for TG and MCC were compared.

Keywords: flammability, microscale combustion calorimetry, thermogravity analysis, thermal degradation, kinetic analysis

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Authors: Arnab Majumdar, Sanjoy Sadhukhan

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Although gun barrel steels are an important variety from defense view point, available literatures are very limited. In the present work, an IF grade Ni-Cr-Mo-V high strength low alloy steel is produced in Electric Earth Furnace-ESR Route. Ingot was hot forged to desired dimension with a reduction ratio of 70-75% followed by homogenization, hardening and tempering treatment. Sample chemistry, NMIR, macro and micro structural analyses were done. Mechanical properties which include tensile, impact, and fracture toughness were studied. Ultrasonic testing was done to identify internal flaws. The existing high strength low alloy Ni-Cr-Mo-V steel shows improved properties in modified processing route and heat treatment schedule in comparison to properties noted earlier for manufacturing of gun barrels. The improvement in properties seems to withstand higher explosive loads with the same amount of steel in gun barrel application.

Keywords: gun barrel steels, IF grade, chemistry, physical properties, thermal and mechanical processing, mechanical properties, ultrasonic testing

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Authors: Seok Hong Min, Tae Kwon Ha

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High strength Fe-36Ni-base Invar alloys containing Al contents up to 0.3 weight percent were cast into ingots and thermodynamic equilibrium during solidification has been investigated in this study. From the thermodynamic simulation using Thermo-Calc®, it has been revealed that equilibrium phases which can be formed are two kinds of MC-type precipitates, MoC, and M2C carbides. The mu phase was also expected to form by addition of aluminum. Microstructure observation revealed the coarse precipitates in the as-cast ingots, which was non-equilibrium phase and could be resolved by the successive heat treatment. With increasing Al contents up to 0.3 wt.%, tensile strength of Invar alloy increased as 1400MPa after cold rolling and thermal expansion coefficient increased significantly. Cold rolling appeared to dramatically decrease thermal expansion coefficient.

Keywords: invar alloy, aluminum, phase equilibrium, thermal expansion coefficient, microstructure, tensile properties

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Authors: H. M. Farghally, N. M. Ahmed, H. T. El-Madany, D. M. Atia, F. H. Fahmy

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Energy is required in almost every aspect of human activities and development of any nation in this world. Increasing fossil fuel price, energy security and climate change have important bearings on sustainable development of any nation. The renewable energy technology is considered one of the drastic approaches taken over the world to reduce the energy problem. The preservation of vegetables by freezing is one of the most important methods of retaining quality in agricultural products over long-term storage periods. Freezing factories show high demand of energy for both heat and electricity; the hybrid Photovoltaic/Thermal (PV/T) systems could be used in order to meet this requirement. This paper presents PV/T system design for freezing factory. Also, the complete mathematical modeling and Matlab Simulink of PV/T collector is introduced. The sensitivity analysis for the manufacturing parameters of PV/T collector is carried out to study their effect on the thermal and electrical efficiency.

Keywords: renewable energy, hybrid PV/T system, sensitivity analysis, ecological sciences

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Authors: C. Trapp, A. Vijay, M. Khorasani

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Decentralised micro-grids with sector coupling can combat the spatial and temporal intermittence of renewable energy by combining power, transportation and infrastructure sectors. Intelligent energy conversion concepts such as electrolysers, hydrogen engines and fuel cells combined with energy storage using intelligent batteries and hydrogen storage form the back-bone of such a system. This paper describes a micro-grid based on Photo-Voltaic cells, battery storage, innovative modular and scalable Anion Exchange Membrane (AEM) electrolyzer with an efficiency of up to 73%, high-pressure hydrogen storage as well as cutting-edge combustion-engine based Combined Heat and Power (CHP) plant with more than 85% efficiency at the university campus to address the challenges of decarbonization whilst eliminating the necessity for expensive high-voltage infrastructure.

Keywords: sector coupling, micro-grids, energy self-sufficiency, decarbonization, AEM electrolysis, hydrogen CHP

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Authors: Yong Ren, Yaping Zhang

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A numerical model has been developed to investigate the thermally triggered release kinetics for drug delivery using phase change material as shell of microcapsules. Biocompatible material n-Eicosane is used as demonstration. PCM shell of microcapsule will remain in solid form after the drug is taken, so the drug will be encapsulated by the shell, and will not be released until the target body part of lesion is exposed to external heat source, which will thermally trigger the release kinetics, leading to solid-to-liquid phase change. The findings can lead to better understanding on the key effects influencing the phase change process for drug delivery applications. The facile approach to release drug from core/shell structure of microcapsule can be well integrated with organic solvent free fabrication of microcapsules, using double emulsion as template in microfluidic aqueous two phase system.

Keywords: phase change material, drug release kinetics, double emulsion, microfluidics

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Authors: Touil Djamal, Fergani Zineb

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In this study, an Organic Rankine Cycle (ORC) with Cyclohexane working fluid is proposed for cogeneration in the cement industry. In this regard: first, a parametric study is conducted to evaluate the effects of some key parameters on the system performances. Next, single and multi-objective optimizations are performed to achieve the system optimal design. The optimization considers the exergy efficiency, the cost per exergy unit and the environmental impact of the net produced power as objective functions. Finally, exergy, exergoeconomic and exergoenvironmental analysis of the cycle is carried out at the optimum operating conditions. The results show that the turbine inlet pressure, the pinch point temperature difference and the heat transfer fluid temperature have significant effects on the performances of the ORC system.

Keywords: organic rankine cycle, multi-objective optimization, exergy, exergoeconomic, exergoenvironmental, multi-objective optimisation, organic rankine cycle, cement plant

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Authors: Talal Al-Bazali

Abstract:

Air drilling has recently received increasing acceptance by the oil and gas industry due to its unique advantages. The main advantages of air drilling include the higher rate of penetration, less formation damage, lower risk of loss of circulation. However, these advantages cannot be fully realized if thermal effects in air drilling are not well understood and minimized. Due to its high frictional coefficient, low heat conductivity, and high compressibility, air can impact the temperature distribution of bit and thus affect its bit performances. Based on energy and mass balances, a transient thermal model that predicts bit temperature is presented along with numerical solutions in this paper. In addition, several important parameters that influence bit temperature distribution are analyzed. Simulation results show that the bit temperature increases with increasing weight on bit and rotary speed but decreases as the standpipe pressure and flow rate increase. These results can be used to optimize drilling operations and flow parameters for an improved bit performance as shown in this paper.

Keywords: air drilling, rate of penetration, temperature, rotary speed

Procedia PDF Downloads 286

Authors: Jamal Alasiri, Naif Hakeem, Saoud Almaslmani

Abstract:

Background: Patients with humeral shaft fractures have two different treatment options. Surgical therapy has lesser risks of non-union, mal-union, and re-intervention than non-surgical therapy. These positive clinical outcomes of the surgical approach make it a preferable treatment option despite the risks of radial nerve palsy and additional surgery-related risk. We aimed to evaluate patients’ outcomes and return to work after surgical vs. non-surgical management of shaft humeral fracture. Methods: We used databases, including PubMed, Medline, and Cochrane Register of Controlled Trials, from 2010 to January 2022 to search for potential randomised controlled trials (RCTs) and cohort studies comparing the patients’ related outcome measures and return to work between surgical and non-surgical management of humerus fracture. Results: After carefully evaluating 1352 articles, we included three RCTs (232 patients) and one cohort study (39 patients). The surgical intervention used plate/nail fixation, while the non-surgical intervention used a splint or brace procedure to manage shaft humeral fracture. The pooled DASH effects of all three RCTs at six (M.D: -7.5 [-13.20, -1.89], P: 0.009) I2:44%) and 12 months (M.D: -1.32 [-3.82, 1.17], p:0.29, I2: 0%) were higher in patients treated surgically than in non-surgical procedures. The pooled constant Murley score at six (M.D: 7.945[2.77,13.10], P: 0.003) I2: 0%) and 12 months (M.D: 1.78 [-1.52, 5.09], P: 0.29, I2: 0%) were higher in patients who received non-surgical than surgical therapy. However, pooled analysis for patients returning to work for both groups remained inconclusive. Conclusion: Altogether, we found no significant evidence supporting the clinical benefits of surgical over non-surgical therapy. Thus, the non-surgical approach remains the preferred therapeutic choice for managing shaft humeral fractures due to its lesser side effects.

Keywords: shaft humeral fracture, surgical treatment, Patient-related outcomes, return to work, DASH

Procedia PDF Downloads 99

Authors: Saeed Khandan Siar, Stefan Tenbohlen, Christian Breuer, Raphael Lebreton

Abstract:

The goal of this article is to investigate the detailed temperature distribution and the fluid flow of an oil cooled winding of a power transformer by means of computational fluid dynamics (CFD). The experimental setup consists of three passes of a zig-zag cooled disc type winding, in which losses are modeled by heating cartridges in each winding segment. A precise temperature sensor measures the temperature of each turn. The laboratory setup allows the exact control of the boundary conditions, e.g. the oil flow rate and the inlet temperature. Furthermore, a simulation model is solved using the open source computational fluid dynamics solver OpenFOAM and validated with the experimental results. The model utilizes the laminar and turbulent flow for the different mass flow rate of the oil. The good agreement of the simulation results with experimental measurements validates the model.

Keywords: CFD, conjugated heat transfer, power transformers, temperature distribution

Procedia PDF Downloads 424