The present study involves experimental analysis of the modified Closed Wet Cooling Tower (CWCT) based on first and second law of thermodynamics, to gain a deeper knowledge in this important field of engineering in Iraq. For this purpose, a prototype of CWCT optimized by added packing under a heat exchanger was designed, manufactured and tested for cooling capacity of 9 kW. Experiments are conducted to explore the effects of various operational and conformational parameters on the towers thermal performance. In the test section, spray water temperature and both dry bulb temperature and relative humidity of air measured at intermediate points of the heat exchanger and packing. Exergy of water and air were calculated by applying the exergy destruction method on the cooling tower. Experimental results showed a significant performance improvement when using packing on the CWCT. It can be observed that the thermal efficiency for the CWCT with packing under a heat exchanger and CWCT with packing above the heat exchanger are approximately 40% and 25% higher than that of the CWCT without packing respectively. As another part of the experiment results, it is indicated that the exergy destruction is directly proportional to air flow rate, cooling water flow rate, inlet cooling water flow rate and inlet Air Wet Bulb Temperature (AWBT) whereas, it is inversely proportional with spray water flow rate. In comparison with the cooling capacity of the tower, it was found that the exergy destruction approximately less than 20%. Exergy efficiency behavior is inversely proportional with the behavior of the exergy destruction. Empirical correlations are obtained to predict water film heat transfer coefficient and air-water mass transfer coefficient considering the influences of operational parameters.
مشكلة البحث :-
ظلت رغبة الانسان في المعرفة وفهم الكون الذي يعيش فيه ، ملازمة له منذ المراحل الاولى لتطور البشرية ، فالانسان بما يتمتع به من امكانات وقدرات وطاقات كامنة استطاع عن طريق تفاعله واحتكاكه الدائم والمستمر والخلاق مع البيئة المحيطة به ان يلاحظ ، ويتخيل ويتذكر ويفكر ويخطط ويبتكر ، مستفيداً من اخطائه في التعرف عليها ، وفي زيادة قدرته على التحكم فيها وتحسينها وتطويره
... Show MoreCopper zinc tin sulfide selenide, Cu2 ZnSn(S1−x Se x)4 , absorbers are promising earth-abundant and environmentally benign materials for low-cost photovoltaic applications. This study investigates the structural and optical properties of Cu 2 ZnSn(S1−x Se x)4 nanostructured thin films prepared by pulsed laser deposition using melt-quenched targets with selenium compositions x = 0.0–1.0. X-ray diffraction revealed that films with low selenium content remained amorphous, whereas higher selenium incorporation promoted the formation of polycrystalline kesterite–stannite phases with preferred orientations along (112), (200), (220), and (312). The crystallite size increased from 12.3 to 17.9 nm as selenium reached x = 1.0, indicating enha
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In this paper, we introduce and study a new concept (up to our knowledge) named CL-duo modules, which is bigger than that of duo modules, and smaller than weak duo module which is given by Ozcan and Harmanci. Several properties are investigated. Also we consider some characterizations of CL-duo modules. Moreover, many relationships are given for this class of modules with other related classes of modules such as weak duo modules, P-duo modules.
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- مشكلة البحث
تشغل مادة طرائق التدريس مكانة متميزة في عملية التعليم والتعلم لما لها من دور كبير وفاعل في إيصال المادة العلمية إلى الطالب بنجاح .
وقد عزى بعض الباحثين التأخر الذي رافق طرائق تدريس التربية الإسلامية إلى ضعف إعداد المدرسين وتأهيلهم التربوي ولا سيما أن عدد غير قليل منهم من كليات غير تربوية فهم خريجو كليات العلوم الإسلامية والجامعة الإسلامية والإدارة والاقتصاد
... Show MoreThe Dictionary of Countries by Yaqut al-Hamawi is one of the most important sources that researchers rely on in everything related to geography in knowing the names of places and countries, and the important historical information it contains about different cities and countries
Parmi les oeuvres d'Albert Camus, qui s'éloignent un peu de sa
tendance générale qui traite les thèmes de l'absurde ,du néant et de la
question de la mort , on trouve son recueil "l'Exil et le Royaume" 1957
qui contient six nouvelles qui sont d'une invention moins épouvantable
(le Renégat , la Femme adultère , les Muets , le Pierre qui pousse , l'Hôte
et Jonas). Ces nouvelles , à l'exception du "Renégat" , ne provoquent pas
les questions philosophiques et dialectiques qui dominent la plupart des
oeuvres d'Albert Camus , Mais ces nouvelles traitent tout simplement la
question d'homme exilé dans son existence et sa recherche perpétuelle
de son royaume.
this research aims it measure the technical efficiency of the branches of the General Company for Land Transport, That scattered geographically at country level, by Data Envelopment analysis (DEA) technique, as this technique relies on measuring the efficiency of a set of asymmetric Decision making units, which is one of the nonparametric mathematical methods for and application related to Linear Programming, and this is what helps the General Company for Land Transport to diagnose its branches performance by benchmarking with each other and determine the performance gap. The research found that there is variation in the level of efficiency in the company's branches
The Dictionary of Countries by Yaqut al-Hamawi is one of the most important sources that researchers rely on in everything related to geography in knowing the names of places and countries, and the important historical information it contains about different cities and countries
يهدف البحث الى التعرف على اثر استراتيجية نجمتين وامنية في تحصيل مادة الكيمياء عند طلاب الصف الثاني المتوسطولتحقيق هدف البحث تم اتباع المنهج التجريبي ذو الضبط الجزئي وتم تحديد مجتمع البحث بطلاب الصف الثاني المتوسط لجميع المدارس الثانموية والمتوسط التابعة لمديرية تربية الكرخ الثانية وتم اخنيار احد هذه المداس بصورة قصدية لتطبيق تجربة ابلبحث الحالي
هدف ال الأسلوب المعرفيّ م الإد ا ركيّ اضة للبنات، والتعرّف على علاقة التنظ ة وعلوم الر ة البدنّ ة التر لّ ة في ات المرحلة الثانّ طال إنّه احثتان اضة للبنات، وأفترضت ال ة وعلوم الر ة البدنّ ة التر ل ة في ات المرحلة الثان عض طال التأمّليّ الاندفاعيّ لدى اس الأسلوب المعرفيّ التأمّليّ الاندفاعيّ لدى عیّنة م الإد ا ركيّ ونتائج مق اس التنظ ة بین نتائج مق
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