Conjugate heat transfer has significant implications on heat transfer characteristics, particularly in thick wall applications and small diameter pipes. In this study, a three-dimensional numerical investigation was carried out using commercial CFD software “ANSYS FLUENT” to study the influence of conjugate heat transfer of laminar flow in mini channels at constant heat flux wall conditions. Two parameters were studied and analyzed: the wall thickness and thermal conductivity and their effect on heat transfer characteristics such as temperature profile and Nusselt number. Thermal conductivity of (0.25, 10, 202, and 387) W/m2C and wall thickness of (1, 5, and 50) mm were used for a channel of (1*2) mm cross-sectional dimensions. Taking the Reynolds number 800 for all cases. The results demonstrate that the conjugate conduction impact is observed at high conductivities and for large wall thicknesses in the studied materials. This impact flattened the wall temperature distribution along the channel wall instead of being an augmented linear profile. Also, it flattens the local Nusselt number due to the axial heat conduction along the walls. It reduces the effect of the entrance region of high Nusselt number while making the fluid temperature profile curved and redistributing the wall heat flux and accumulating it toward the leading edge. A decrease was observed in the average Nusselt number of 8% when increasing wall thickness from 1 mm to 50 mm for the same thermal conductivity of 10 W/m2C, while an increase in Nusselt number of 19% with thermal conductivity changes from 0.25 W/m2C to 10 W/m2C.
Background: The world is in front of two emerging problems being scarceness of virgin re-sources for bioactive materials and the gathering of waste production. Employment of the surplus waste in the mainstream production can resolve these problems. The current study aimed to prepare and characterize a natural composite CaO-SiO2 based bioactive material derived from naturally sustained raw materials. Then deposit this innovative novel bioactive coating composite materials overlying Yttria-stabilized tetragonal zirconia substrate. Mate-rials and method; Hen eggshell-derived calcium carbonate and rice husk-derived silica were extracted from natural resources to prepare the composite coating material. The manufac-tured powder was characterized
... Show MoreThe population of Ephemeroptera was studied in three selected stations of Rawanduz River (Gali Ali Beg water fall, Rawanduz River and after the junction of these two waters) during the three seasons of spring, summer and autumn in 2016. In addition,sixteen physicochemical parameters (pH, EC, turbidity, DO, BOD5, NO3, TDN, TDP, HCO3-, Hardness, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, Na% and SAR) of water in these stations were estimated and used to calculate the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). Eleven species of aquatic insects were identified,which belong to four families of th
... Show MoreThis study involved the treatment of textile wastewater contaminated with direct blue 15 dye (DB15) using a heterogeneous photo-Fenton-like process. Bimetallic iron/copper nanoparticles loaded on bentonite clay were used as heterogeneous catalysts and prepared via liquid-phase reduction method using eucalyptus leaves extract (E-Fe/Cu@BNPs). Characterization methods were applied to resultant particles (NPs), including SEM, BET, and FTIR techniques. The prepared NPs were found with porous and spherical shapes with a specific surface area of particles was 28.589 m2/g. The effect of main parameters on the photo-Fenton-like degradation of DB15 was investigated through batch and continuous fixed-bed systems. In batch mode, pH, H2O2 dosage, DB15 c
... Show MoreIt was rumored in the grammatical circles that the (short) refrigerant is only a copy of (book) Sibweh, except some of the views that violated it, or some of the evidence that increased it; On the (brief) or not, the researcher has chosen the subject (what is going away and not leave) a field of study of the budget, has come on three demands, the first devoted to the study of the term, and the second to explain the methodology of scientists in the presentation of the topic, and the third was limited to the study of the evidence they invoked .
God grants success
The current study used extracts from the aloe vera (AV) plant and the hibiscus sabdariffa flower to make Ag-ZnO nanoparticles (NPs) and Ag-ZnO nanocomposites (NCs). Ag/ZnO NCs were compared to Ag NPs and ZnO NPs. They exhibited unique properties against bacteria and fungi that aren't present in either of the individual parts. The Ag-ZnO NCs from AV showed the best performance against E. coli, with an inhibition zone of up to 27 mm, compared to the other samples. The maximum absorbance peaks were observed at 431 nm and 410 nm for Ag NPs, at 374 nm and 377 nm for ZnO NPs and at 384 nm and 391 nm for Ag-ZnO NCs using AV leaf extract and hibiscus sabdariffa flower extract, respectively. Using field emission-scanning electron microscopes (FE-
... Show MoreA series of new aromatic polyesters have been synthesized by polycondensation of different aromatic diols (M1, M2 ,M3) with different dicarboxlic acids (4,4'azo di benzoic acid, malic acid and adipic acid) using dibutyltine dilaurate as catalyst . The preparation of thermally stable polyesters was successfully applied with good yields (60-85%). All polyesters (PE1-PE4) containing aliphatic methylene linkage, and azo group in the main chain. The resulted polymers are readily soluble in aprotic polar solvents , such as (pyridine , CHCl3 , CH2Cl2 , NaOH , H2SO4 , HNO3 , acetone , benzene , DMF , DMSO , THF) without need for heating. Thermal analysis of polyesters by Thermo Gravimetric Analysis (TGA) reveals that these aromatic polyesters po
... Show MoreBackground: Implant stability is a mandatory factor for dental implant (DI) osseointegration and long-term success. The aim of this study was to evaluate the effect of implant length, diameter, and recipient jaw on the pre- and post-functional loading stability. Materials and methods: This study included 17 healthy patients with an age range of 24-61 years. Twenty-two DI were inserted into healed extraction sockets to replace missing tooth/ teeth in premolar and molar regions in upper and lower jaws. Implant stability was measured for each implant and was recorded as implant stability quotient (ISQ) immediately (ISQ0), and at 8 (ISQ8) and 12 (ISQ12) weeks postoperatively, as well as post-functional loading (ISQPFL). The pattern of implant
... Show MoreNew complexes of the type [ML2(H2O)2] ,[FeL2(H2O)Cl] and [VOL2] were M=Co(II),Ni(II) and Cu(II) ,L=4-(2-methyl-4-oxoquinazoline-3(4H)-yl) benzoic acid were synthesized and characterized by element analysis, magnetic susceptibility ,molar conductance ,FT-IR and UV-visible. The studies indicate that the L acts as doubly monodentate bridge for metal ions and form mononuclear complexes. The complexes are found to be octahedral except V(IV) complex is square pyrimde shape . The structural geometries of compounds were also suggested in gas phase by theoretical treatments, using Hyper chem-6 program for the molecular mechanics and semi-empirical calculations, addition heat of formation(?Hf ?) and binding energy (?Eb)for the free ligan
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