The printed circuit heat exchanger is a plate type heat exchanger with a high performance and compact size. Heat exchangers such as this need a unique form of bonding and other techniques to be used in their construction. In this study, the process of joining plates, diffusion bonding, was performed and studied. A special furnace was manufactured for bonding purposes. The bonding process of copper metal was carried out under specific conditions of a high temperature up to 700 oC, high pressure of 3.45 MPa, and in an inert environment (Argon gas) to make tensile samples. The tensile samples are cylindrical shapes containing groves representing the flow channels in the printed circuit heat exchanger and checking their tensile strength in addition to the standard shape of the tensile specimen to check the yield and ultimate strength of the copper. A higher tensile strength was obtained for diffusion bonded specimens than the yield strength of copper, up to 1.35 times the copper yield strength. The tensile strength decreases with the increase in the number of groves and the decrease in the distance between one grove and another. This is because the stress is concentrated in the sharp corners. A prototype heat exchanger of two plates and a header to be tested for its compressive strength was also manufactured. The results showed that the bond bears an air pressure of up to 8 bar without fail. It was also found to withstand a hydraulic pressure of up to 60 bar until it reached failure.
The performance and lifetime of the flexible asphalt pavement are mainly dependent on the interfacial bond strength between layer courses. To enhance the bond between layers, adhesive materials, such as tack coats, are used. The tack coat itself is a bituminous material, which is applied on an existing relatively non-absorbent surface to ensure a strong bond between the old and newly paved layer. The primary objective of this study was to evaluate the effects of various types of tack coat materials on interlayer bond strength and to determine the optimal application rate for each type. The tack coat types used in this paper were RC-70, RC-250, and CSS-1h. Both laboratory-prepared and field-constructed hot mix asphalt concrete pavements usin
... Show MoreThe slums one of the main problem plaguing the city of Baghdad in general and
the unity of municipality of New Baghdad, especially, where the characteristics of the study
area a prominent role in population growth and the emergence of slums where a private,
although the region suffer from the housing crisis is the lack of the number of housing units
compared to the number of families in which, With high land prices and the level of rent
which was accompanied by the absence of the law, which was followed by the year 2003, has
become the study area and one of the most municipalities of the city of Baghdad Contain
slums which took fills abandoned buildings and acquires vacant land agricultural ones and
allocated to d
The research aimed to diagnose and interpretation of impact nature between Communities of practice dimensions (participation and spreading knowledge, confidence, social capital build) deportation strategic change choices (reengineering business process, business re-structuring, business innovation) in construction companies in the Iraqi Ministry of Construction and Housing, the research tested 4 construction companies working in investing sector in Iraq, the research applied on a sample of 102 persons who participated in Communities of practice distributed in several administrative levels (directors, division directors, project directors and engineers) the research used questionnaire as a main tool for dat
... Show MoreBackground: Significant numbers of patients with spinal tuberculosis (TB), especially in developing countries, still present late after disease onset with severe neurological deficits.
Objective:This study was conducted to assess the outcome of surgery in patients with tuberculosis of the spine with motor deficits.
Type of the study: Retrospective study.
Methods: We retrospectively analyzed data obtained in all the patients with severe motor deficits due to spinal TB admitted to and surgically treated in four hospitals in Baghdad/Iraq during the period from January 2012 to January 2014. History, examination, imaging, histological, postoperative, a
... Show Moren-Hexane conversion enhancement was studied by adding TCE (Trichloro-ethylene) on feed stream using 0.3%Pt/HY zeolite catalyst. All experiments were achieved at atmospheric pressure and on a continuous laboratory unit with a fixed bed reactor at a temperature range 240-270◦C, LHSV 1-3h-1, H2/nC6 mole ratio 1-4.
By adding 435 ppm of TCE, 49.5 mole% conversion was achieved at LHSV 1h-1, temperature of 270ºC and H2/nC6 mole ratio of 4, while the conversion was 18.3 mol% on the same catalyst without adding TCE at the same conditions. The activation energy decreased from 98.18 for pure Pt/HY zeolite to 82.83 kJ/mole by adding TCE. Beside enhancement the activity, selectivity and product distribution enhanced by providing DMB (Dimethyl b
Different coating layers of fluorescent agent (FCA) on the solar cells were used. An increase of 35% in the energy conversion efficiency of the solar cell have been obtained. This increase is attributed to the reduction ofthe reflected light, eflection spectra show low values at higher thickness which explained the increase ofthe conversion efficiency with increases of layer thickness.
Implantation of blastocyst is considered as a sensitive process in the life of growing embryo. Thus this critical period could be under threat from the harmful effect of many drugs ,among them is the carbamazepine which is used by many women for a treatment of epilepsy . The present experiment was designed to study the effect of this drug on the process of implantation ;especially during the days 7 and 9 of pregnancy. For those purpose 169 pregnant albino mice, of 25 gm weight for each one, were used .The mice were divided into control group given orally normal saline, and treated group given orally carbamazepine with concentration of 15 mg\kg. Samples from pregnant uteri containing the embryos were used. They were first fixed in Boun's sol
... Show MoreСатья посвящена выделению и описанию функциональных стилей русского языка. В работе будет предствлена стилистическая характеристика заимствованной лексики, которая в некоторых случаях заменяет собственно русские слова, что может приводить к затемнению смысла высказывания, эвфемизации его, кроме того, заимствования заполняют определенные стилистические книши, образовавшиеся в связи со структурны
... Show MoreThe aim of the present work is to develop a new class of natural fillers based polymer composites with sawdust (S.D) which used two particle sizes (1.2 μm & 2.3 μm) and different weight percentage from sawdust (10%, 15%, and 20%). The mechanical properties studied include hardness (shore D) for all samples at normal conditions (N.C). The unsaturated polyester (UPE) and its composites samples were immersed in water for 30 days to find the effect of particle size of sawdust (S.D) on the weight gain (Mt %) by water for all the samples, also to find the effect of water on their hardness. The results show that the composite materials of sawdust (S.D) fillers which has particle size (1.2 μm) better than (2.3 μm) particle size bef
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