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Effects of Arrangement and Surface Roughness of Transverse Studs on Heat Transfer in Round Tubes
Get PDF Four heat transfer enhancing tubes (tubes A – D) with transverse studs are fabricated and tested. The studs are regularly welded in the tubes at a pitch of 53.2 mm. The inner and outer diameters of the tubes are 13.3 and 17.3 mm, respectively. Tubes A, B and C use the same threaded studs (M4) as flow disturbing device, but the arrangements of the studs on the tube walls are different. Tube D adopts the same stud arrangement as tube A, but its studs are smooth instead of threaded. Air is the working fluid in the tubes. For the Reynolds number (Re) in the range of 4000 to 23000, fluid friction and heat transfer data of the four heat transfer enhancing tubes are measured and the results are compared with those of a smooth tube. The transverse studs are quite effective for enhancing the heat transfer in the tubes. Regardless of the Re value and stud arrangement, a twofold increase in the convection heat transfer coefficient can be achieved. It is also found that the stud arrangement and the stud surface roughness are insignificant to the heat transfer. A frequent variation in stud direction or a rough stud surface would result in an increase in pressure drop, instead of an increase in heat transfer
Performance Evaluation of a Modified DC Compressor Powered by Solar Energy
Get PDF In this study, a modified direct current compressor (MDC) is tested experimentally. The experimental study is conducted in order to observe the performance of a solar energy powered MDC. Then, the performance of this MDC is compared with brand new direct current compressors (BNDC) in the market. The experimental setup has a mini fridge with 50 liters capacity, a photovoltaic panel, a battery, a charge regulator and measurement equipments. Also, a pyranometer is used to define solar radiation on the photovoltaic panel. Experiments are conducted for various cabinet loads such as no storage items, low, nominal and over load at steady state condition
Homoclinic Solutions for Some Nonperiodic Fourth Order Differential Equations with Sublinear Nonlinearities
Get PDFIn this paper we investigate the existence of homoclinic solutions for the following fourth order nonautonomous differential equations; u(4) + wu’’ + a(x)u = f (x,u), (FDE) where w is a constant, a ɛ C(R, R) and f ɛ C(R x R, R) . The novelty of this paper is that, when (FDE) is nonperiodic, i.e., a and f are nonperiodic in x, assuming that a is bounded from below and f is sublinear as | u |→ +ꚙ , we establish one new criterion to guarantee the existence and multiplicity of homoclinic solutions of (FDE). Recent results in the literature are generalized and improved
Some Technological Pretreatments Applied During Olive Oil Extraction: Impacts on Quality Parameters and Minor Constituents
Get PDF The mechanically extraction of olive oil has three main steps: preparation of the paste (crushing with a mechanical metal crusher and kneading with malaxer), solid-liquid and liquid-liquid separation (horizontal-axis centrifugal separator (decanter)). For every extraction process (solid-liquid separation type), the factors such as temperature, time, adjuvants, amount of processing water oxygen and processing type can be changed. Moreover, the need to production of high-quality virgin olive oil at the highest yield and minimum cost, as well as using an environmentally friendly olive oil production encourages the processing of olive oil in different forms and research of new technologies. The main goal for this purpose is to reduce the process time and increase the extraction yield along with transform the discontinuous malaxing step in a continuous phase and improve the working capacity. Another important aspect to consider is the reduction of energy requirements of the process, thereby reducing both environmental and financial costs. This trend triggered the rapid progress in the application of emerging technologies in olive processing. Ultrasounds (US), microwaves (MW), and pulsed electric fields (PEF), flash thermal conditioning (FTC) are emerging technologies that have already found application in the virgin olive oil extraction process on pilot scale plants. This paper aims to describe the basic principles of these technologies as well as the results concerning their impact on virgin olive oil yields. In this review, different technological processes being implemented in recent years to prevent the loss caused by the conventional methods in the production of olive oil and effects of these technological treatments on quality and chemical characteristics of the olive oil is gathered
Energy Optimization of Reactive Distillation Columns for Biodiesel by Pinch Point Analysis
Get PDFThis papers aims at optimizing the energy consumption of reactive distillation columns for simulation of biodiesel production. The design of the proposed biodiesel production uses lauric acid (C12H24O2) as feedstock in a reactive distillation column. In order to do so, selection has been done by selecting the design parameters of the column: the number of stages, feeding flows, reflux ratio, the height of the transfer unit as well as the analysis of the Sulzer BX packing. ASPEN PLUSTM simulation software has been used to work out the thermodynamic steady state of the system on which the optimization is based on. Energy optimization is carried out through the Pinch Point Analysis. Thus it has been proven that the Pinch Point Analysis allows optimization of the heat exchange network in a distillation column. Results showed that it is possible to reduce drastically the energy requirements of a distillation process up to 60 %. The heat exchange network showed that is promising to design more energy-efficient and environment-friendly distillation process for production of biodiesel
Interaction of Concept and Design
Get PDF During the design process, various methods are used to develop the creative thinking. One of such methods is to commence the design process with a concept. The study aiming to emphasize the importance of concept covers a workshop themed as design with concept. The workshop was undertaken within the scope of Flexibility in Design course of Department of Interior Design, Faculty of Architecture under the Karadeniz Technical University. The workshop was structured as four phased. In the first phase, the students were provided with information regarding conceptual design; then in the second phase, the students were required to choose from one of the buildings that worldwide known architects used conceptual design method and to get information on the interpretation of method and in the third phase they were asked to design their forms derived from the concept. The last phase was comprised of discussing the similarities and differences of new forms generated from the concept. The study is considered as significant for the students in the way of experiencing the concept of a building designed by a concept and designing their own forms without seeing the building
Study on Stress Sensitivity of Longmaxi Formation Shales in East Sichuan
Get PDF Depletion development is the main way of shale gas reservoir development. The stress sensitivity of shale will have made a great impact on the correct evaluation of shale gas productivity. At the time that the shale gas reservoir in Fuling is on development, the study of stress sensitivity of shale gas reservoir gas formation, Longmaxi formation, will make a great significance to the high efficient development of shale gas reservoir in Fuling even to the shale gas development in our country. This article uses the Longmaxi formation outcrop in east Sichuan and the PDP-200 pulse decay permeameter applied for the evaluation of stress sensitivity of shale permeability. Two different plans, constant confining pressure-decreasing inner pressure test and constant internal pressure-increasing confining test, are adopted to do the permeability experiments of the same core with horizontal bedding. The results show that with the increase of effective stress affected on the shale, the permeability of shale decreases exponentially in tests, and according to decline index that decreasing process is divided into two sections. It respectively embodies the stress sensitivity of shale fracture permeability and shale matrix permeability. At the same time, the tests show permeability hysteresis when compare two tests: constant confining pressure test and constant internal pressure test. And the fracture closing pressure showed in the internal pressure test is lower than the confining pressure test result
On the Study of Racah Parameter B for Nickel (II) and Cobalt (II) Compounds
Get PDF The ligand field strength (Dq) and interelectronic repulsion (B) have been calculated for nickel (II) and cobalt (II) compounds by Underhill and Billing [1] based on v2 and v3 values. They solved the quadratic equation 340(Dq2-18(v2+v3) Dq+ v2 v3=0 in Dq for octahedral. Then, the B value was determined using the equation v2+ v3−30Dq−15B=0. But, the first equation has real and imaginary solutions and it’s difficult to determine the imaginary one. In addition, in many cases there is no solution of this equation as well as in the case of CoO (d7 oct.). For octahedral, the above two equations can be considered as a system of two equations with two unknowns which can be solved if we have v2 and v3 values and vice versa. Similarly, for tetrahedral, the former two equations also can be solved for Dq and B. Using Newton–Raphson iterations, Dq and B values are exactly determined for octahedral and tetrahedral systems. The obtained values of Dq and B were compared with those previously reported
Production of Tomato Stalk Biochar and its Usage in Hydrophonic Agriculture
Get PDFTomato stalk is a waste remained after harvesting in agricultural productions. These wastes can be utilized as biochar for various purposes such as fuel, absorbent and soil improver. In this study, in order to waste utilization, biochar production from tomato stalk under different experimental conditions was carried out and effect of temperature, nitrogen gas flow and heating rate on yield of biochar was investigated. Characterization of biochar was performed with FTIR, TGA and SEM analysis. The highest biochar yield was obtained at the temperature of 773 K, heating rate of 5 K/min and inert gas flowrate of 500 ml/min. The highest yielded tomato stalk biochar was used as a supporting material for the tomato seedling planted in the hydroponic system of greenhouse. The tomato stalks obtained as a waste after harvesting in greenhouse were used for biochar production and biochars were applied as supporting material in greenhouse again, so, zero waste idea for a greenhouse was carried out. It has been observed that the supporting material provided a little more growth in the tomato seedling because of water and nutrient holding capacity
On Special Fuzzy Differential Subordinations Using Generalized Sala gean Operator and Ruscheweyh Derivative
Get PDF: In the present paper we establish several fuzzy differential subordinations regardind the operator RD!,"m , givenby RD!,"m : A # A, RD!,"m f (z) = (1#")Rm f (z)+"D!m f (z), where Rm f (z) denote the Ruscheweyh derivative, D!m f (z) is thegeneralized S !a l!a gean operator and A = { f !H(U), f (z) = z + a2z2 +…, z !U} is the class of normalized analyticfunctions. A certain fuzzy class, denoted by RDmF (!,",# ), of analytic functions in the open unit disc is introduced bymeans of this operator. By making use of the concept of fuzzy differential subordination we will derive various properties and characteristics of the class RDmF (!,",# ). Also, several fuzzy differential subordinations are established regardingthe operator RD!,"m