The evacuated tube solar collector ETC is studied intensively and extensively by experimental and
theoretical works, in order to investigate its performance and enhancement of heat transfer, for Baghdad climate
from April 2011 till the end of March 2012. Experimental work is carried out on a well instrumented collector
consists of 16 evacuated tubes of aspect ratio 38.6 and thermally insulated tank of volume 112L. The relation
between convective heat transfer and natural circulation inside the tube is estimated, collector efficiency, effect of
tube tilt angles, incidence angle modifier, The solar heating system is investigated under different loads pattern (i.e
closed and open flow) to evaluate the heat loss coefficient from tank and tubes, test the collector with various
aspect ratios (32.9 and 27.2). The enhancement in collector performance is studied by using two reflectors (Flat
Plate and Curved Plate) and nanofluid (Water-AL2O3).Theoretical work is run by software (Fluent 6.3), to compute
the velocity and temperature profiles within the tube, for different tube diameters, effect of tube junction angle and
stagnant region in the bottom of the evacuated tube. The experimental results shows that the heat loss coefficient
for tube is W/m2.K and for tank is W/m2.K, the maximum collector temperature is 79°C in winter and
99°C in summer, while that belong to nanofluid collector is 99°C in winter. The best tilted angle (optimum) of
evacuated tube is 41° annually. The collector efficiency increased when using nanofluid of (1, 0.6, 0.3)% volume
fraction as(28.4, 6.8, 0.6)% respectively. The efficiency decreases as (33, 62)% when decreasing tube aspect ratio
from 38.6% to 32.9% and 27.2% respectively. An increase of (16.9 and 7.08)% in collector efficiency is obtained
when using curved and flat plate reflectors respectively. From simulation the best junction angle of the tank is
22.5°. The stagnant region is influenced with changing heat flux, tilted angle and aspect ratio.
Through the study of social work and social policy ( problems of marginalization and empowerment opportunities ) and taken a theoretically descriptive and analytical and highliyhed the role of social work in social policy its achieved only through community intraction and paamong all parties and according to social policies include of material resources and haman and integrated in to the planning and development framework with the aim of providing social services for allsegments of society and become the study in social work that include the introducation / and five chapters each chapter in cludes several detectives and each complements the other .
1 – The absence of social development projects on social policy .
2 – social pol
This study deals with the thems of "in-betweeness" in the modern Afro-American Drama, drawing upon the accumulated literature of the colonial and postcolonial studies. In-betweeness appears in these studies under the canopy of the terms mimicry, hybridity and liminality which refer to a transformative, in-between state of being. It also refers to themutual relations holdingbetween man and his cultural space.
This concept is fitting the Afro-American playwright Amiri Baraka's plays and his violent, revolutionary theatre. In his play Dutchman (1964), Clay, the protagonist, is a good example of the two-ness or in-betweeness. He finds difficulty choosing between the ethnocentric white culture and the black culture.He allows
... Show MoreThe research team seeks to study the phenomena of random housing in Iraqi society in general and Baghdad city in particular by standing on the causes behind this phenomena and its relation with security situation in Baghdad. The researchers adopted a theoretical and practical framework. The main objective is to diagnose the risks caused by the escalation of slums in Baghdad city.
Rheumatoid arthritis (RA) is a systematic autoimmune disorder with chronic inflammation changes of unknown etiology. Various synovial inflammatory and proliferative alterations may contribute to the cartilaginous tissues and invasive bony tissues, leading to destructive joints and malformed bones. This disease is mostly due to infective microorganisms or genetic susceptibility causing immune system disturbances through triggering both T-cells and B-cells. Furthermore, different immune cells may secret cytokines, which are responsible for some RA pathogenesis activity. From ninety individuals, serum sample was collected; thirty of them were normal and sixty cases were patients with RA attended a privet medical clin
... Show MoreThis research presents the concepts of compatibility and edge spaces in
Phraseological or phraseological turn - unchanged in structure and composition, integral in meaning and lexically indivisible phrase or sentence, performing the function of a separate dictionary unit - lexemes. Idioms are found in any language of the world. But such a number of winged phrases, as in Russian, is nowhere else. Idioms play a role in displaying the national-cultural characteristics of any language. They very clearly and accurately reflect the characteristics of the perception of the world, the characteristic features of the material and spiritual life of native speakers, his mentality.
This study deals with the concepts of Colonialism and Civilization in Aimé Cesaire’s A Tempest. The concern of this study is to discuss how postcolonial writers are continually re-writing the Western canonical works as a reaction to the European cultural hegemony. The Western representations of the black are products of specific moments and developments in history and culture. A Tempest reflects a certain historical moment in the decolonization process.
A Tempest is analysed to reveal the counter literary strategy used by Aimé Cesaire, and to disclose the reasons why re-writing and writing back are considered as vital and inescapable tasks. Shakespeare’s The Tempest, which deals with the
... Show MoreSince I live in a society in which violence has become widespread, and killing among its own people flared up till they began to kill under the excuse of taking shelter, in these pages I would like to explain the status of taking shelter in the light of Islamic Law (Sharia), exploring scholars’ opinions in the legitimacy or illegitimacy of this issue according to the legal standards.
And, to acquaint people, and myself in the first place, with the true nature and the gravity of this issue; to expose it to those who are unaware of it; to remind those who are already aware of it. I would refute the fabrications, remove the suspicions which surround it untill it made the forbidden permissible; the wrong right. I would explain to those
There is a real problem when adding micro elements to the soil as a result of fixation, sedimentation, washing or toxicity, and thus economic loss. The plant needs micro elements in very small quantities that do not burn the leaves or cause poisoning to plants, including iron, zinc and boron, as they are essential elements for growth and completing the plant's life cycle, and increase the plant's resistance to diseases and insects, activate enzymes, and form the chlorophyll molecule, in addition to their role in oxidation and reduction processes and vital processes. The use of fertilizers with their modern technology has made the process of activating seeds or foliar nutrition a matter of interest to researchers as a complementary process t
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