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On Monotonic Solutions of A Nonlinear Integral Equation of Volterra Type
Get PDFWe study a nonlinear integral equation of Volterra type in the Banach space of real functions defined and continuous on a bounded and closed interval. Using a technique associated with measure of noncompactness we prove the existence of the nondecreasing solutions to a nonlinear integral equations of Volterra type in C [0, 1]. We give also one example satisfying the conditions of our main result but not satisfying the conditions of the main result in [1]
Energy Analysis and Modeling Study of Combined Activated Carbon-Silica Gel/Methanol Adsorption Ice Production System
Get PDFIn this article, the transient modelling for a new construction of the Adsorption cold production was investigated. This system, named in this work the combined Adsorption Ice Production system (com-AIP system), was filled by both silica gel (SG) and activated carbon (AC) together in one adsorption reactor as the adsorbent and methanol as the adsorbate and refrigerant. A fined-tube heat exchanger was designed (named combined adsorption reactor) in order to contain two different adsorbents in the adsorption reactor and increase the heat transfer ability between the particles of adsorbents and heat exchanger fins. As a result the input energy required from the external heat source is saved and the coefficient of performance COP of the com-AIP system is improved. The mass flow rate of refrigerant increases and consequently, the refrigeration energy Qe rises too. A cycle simulation computer program of this innovative bed was developed to analyze the refrigeration energy and COP variations by varying heat transfer fluid (hot, cooling and chilled water) inlet temperatures and adsorption/desorption cycle time. The transient behavior of heat and mass transfer fluids has been also studied. Under the standard test conditions of 100 °C hot water, 24 °C cooling water, and 15 °C chilled water inlet temperatures, the simulation results showed that the amount of the ice produced per cycle of 5.34 kg and 0.73 COP can be achieved from the com-AIP system. It was found that the system performance is very much sensitive to the mass flow rate of the refrigerant. The cycle time of the system is not dependent on the amount of the adsorbents but is strongly dependent on driven temperature of heat exchange fluid and the design of the heat exchanger. The com- adsorption reactor allows using the advantages of physical properties of both adsorbents SG and AC. Consequently, this innovative com-AIP system utilizes effectively low-temperature heat sources of temperature between 65 and 100 °C, because of the inferior thermodynamic properties of methanol and the low regeneration temperature from silica gel and activated carbon as adsorbents. This strategy (com-AIP system) is completely different from the conventional adsorption reactors, which are filled with one adsorbent in one bed or in two beds
Analysis of Entropy Generation in a Generalized Couette Flow between Two Concentric Pipes with Buoyancy Effect
Get PDF Heat transfer and entropy generation analysis in buoyancy driven generalized Couette flow of variable viscosity fluid within the annulus of two concentric cylindrical pipes are theoretically investigated. It is assumed that the inner cylinder is fixed while the outer one is subjected to axial motion. The governing nonlinear equation models are obtained and solved numerically using shooting quadrature. The results for velocity and temperature profiles are utilized to compute entropy generation number and the Bejan number. Relevant results are displayed graphically and discussed quantitatively
Numerical Study of a Turbulent Single-Stage Axial Flow
Get PDFThis paper studies the flow in an axial fan with a rotor in front and stators (vanes) in the rear. This configuration is typical of a single-stage axial flow turbo machine. The standard  model with enhanced wall treatment. Interaction between these components is determined considering the rotor and stator together in a single calculation. Numerical calculations have been performed to investigate the effects of different angular velocities on pressure contours, mass flow rates and total pressure and the results have been shown and discussed through figures. The results show that the increase of angular velocity has a significant effect on the governing physical parameters
Asymptotic Optimality of Three Stage Design for Estimating Product of Means with Applications in Reliability Estimation and Risk Assessment
Get PDFThe one-parameter exponential family is a practically convenient and widely used unified family of distributions, which contains both discrete and continuous distributions that can be used for practical modelling, such as the Binomial, Beta, Normal, etc. The problem of estimating product of means has been explored for independent populations from one-parameter exponential family in a general sense, with a three-stage sampling design proposed and proven to be first-order efficient. The purpose of this paper is to apply the theoretical results to specific applications and to provide practical guidance on implementing the proposed sequential design. One popular application problem of interest is to estimate the system reliability, for which a Beta-Binomial model will be adopted. The other practical problem, which is often encountered in environmental study, is risk assessment and a Normal-Normal model will be used for the case
Energy and other Key Performance Indicators for Buildings– Examples for Hellenic Buildings
Get PDFBuildings are the leading energy consuming sector, representing about 40% of the final energy consumption in Europe. Different key performance indicators are available that can support the diverse needs and priorities of stakeholders in their efforts to improve the overall energy performance of buildings. The work first reviews the energy use and characteristics of European buildings, the main European legislation and technical developments that drive the efforts for lowering energy consumption. The main indicators that are used during the design, construction and operation of buildings are elaborated and when possible quantified, along with pertinent standards and regulations for guidance. Using common energy related indicators, a case study then focuses on Hellenic buildings and provides an insight on their performance, exploiting data from energy performance certificates. The contents document relevant work in information and communications technology for delivering simulation, modelling, analysis, monitoring and visualization tools, along with ongoing efforts to exploit building typologies for realistic assessment of energy use, during the design and operation of buildings. Future priorities are also outlined that support the ongoing European efforts to refurbish the existing building stock and the decision making process for setting effective policies towards nearly zero energy buildings
Catalytic Cracking of Vacuum Gas Oil and Used Lubricating Oil on Oil Shale Ash
Get PDFIn this research, Vacuum Gas Oil and/or used lubricating oil is subjected to thermal cracking (pyrolysis) after impregnation on oil shale ash to obtain lighter molecular weight components. The spent oil shale of the thermal cracking step is subjected to further heat treatment in open air at 950oC to react any organic compounds and mineral carbon to metal oxide. Used and/or fresh lubricating oils are impregnated on oil shale ash particles. Ash is soaked for 24 hours to allow absorption of the VGO or lubricating oils into the pores of the ash material. Oil shale ash which is known to contain several metal oxides such as CaO, SiO2, and lesser quantities of Fe2O3, Al2O3, K2O, Na2O, etc. possesses inherent catalytic nature to crack heavy hydrocarbons to produce lighter components.The absorbed Vacuum Gas Oil and/or lubricating oil inside the pores of the oil shale ash, is allowed to crack at 600oC temperature. Cracking of VGO is conducted in a fixed bed reactor under nitrogen, steam environments. The weight ratio of the absorbed oil into the pores to oil shale ash is 1:1 ratio.The particle size was in the range of 20-25 mm. The liquid products indicated 20 vol% falls in the kerosene fraction specifications where as Approximately 50 vol% is diesel cut. Residue which boils at higher than 370 oC constituted about 30 vol% of the liquid distillate.Steam presence in the reaction media affected the composition of the product as measured in density increase. The sulfur content of the produce is found to be 0.75 wt%
Phenol and Parachlorophenol Removal Using Granular Activated Carbon
Get PDFThe main goal of the present work is to remove phenol and parachlorophenol from synthetic solution using granular activated carbon (GAC). Two carbon types are used, the first is commercial supplied to Iraqi market by Spanish company (referred to as CGAC) and the second is manufactured using Iraqi waste material, referred to as MGAC. The experiments are performed according to batch and continuous mode (granular activated carbon adsorption column). The results show that both pollutants can be removed and the breakthrough and exhaustion times are proportional with the thickness of GAC and inversely proportional with the inlet pollutants concentration and surface over flow rate (SOR). The results also indicated that adsorption capacity is inversely proportional with SOR and it is directly proportional with the thickness of GAC column and pollutants concentration. MGAC gives better performance as compared with CGAC. In the present work, it is proved that adsorption capacity is a function of the operating conditions, carbon and adsorbent type and it is not pure carbon property. The results indicated also that Langmuir model fit the experimental data fairly
Modeling of the Compression Process for Refrigerants R134a and R1234yf of a Variable Speed Reciprocating Compressor
Get PDFThis paper presents a robust computational model to predict the behavior of a variable speed reciprocating compressor, incorporating infinitesimal displacements to calculate state by state according to the piston movement. The philosophy of the model is to consider eight sub internal processes: heat transfer on the suction and discharge internal lines, pressure drop across the suction and discharge valves, expansion, suction, compression and discharge. The input variables are: pressure and temperature on the suction (before starting the compression process), discharge pressure (after the compression process completed) and rotation speed, with this the model is able to compute the output parameters like: mass flow rate, power consumption and discharge temperature. With the development of the model, the behaviors of R1234yf and R134a are analyzed. Then the model is validated with experimental data using these both refrigerants, concluding that the model predict with an error of ±10% for the mass flow rate and power consumption, and with an error of ±1 K for the discharge temperature. In the validation, differences in energy behavior for the two refrigerants are discussed; the compressor with R1234yf as working fluid increases its power consumption and delivers greater mass flow rate with low temperature compared when the working fluid on the compressor is R134a
A Simple Method for Determination of Protodioscin in Tribulus Terrestris L. and Pharmaceuticals by High-Performance Liquid Chromatography Using Diode-Array Detection
Get PDFThe Tribulus terrestris L. (Zygophyllaceae) is a known medical plant used in traditional and folk medicine worldwide. The steroid saponine protodioscin, an active component found in this plant, serves as a marker for quality control of plant raw materials. In this study, we developed a simple and selective method for determination of protodioscin using convenient High-Performance Liquid Chromatographic (HPLC) laboratory equipment. The detection was performed by Diode-Array Detector (DAD). The proposed method was fully validated and according to the validation results, it was accurate and precise. It was proven to be linear over a protodioscin concentration range of 10,9 to 544.9 µg/mL. The low values of limit of detection (LOD) and limit of quantitation (LOQ) demonstrated adequate sensitivity (16.0 µg and 48.6 µg protodioscin per g plant material, respectively). The proposed method was successfully applied for quality control of a raw plant material intended for use in pharmaceutical industry, as well as for determination of protodioscin in a commercially available pharmaceutical formulation. The positive identification of protodioscin in analyzed samples was done by comparison of retention times of chromatographic peaks and their UV spectra. The content of protodioscin in analyzed samples was: 0.65 – 0.73 % in a raw plant material, and 0.38 % in tablets, respectively