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:
بين الحين والآخر تتصاعد الصيحات مطالبة بإصلاح النظام التعليمي لكي يتوافق هذا النظام مع ما يحدث في العالم من تطورات علمية وتكنولوجية تترك بصماتها على مختلف قطاعات الحياة .
ويعد المعلم وبلا شك ركنا أساسيا في هذا النظام ،وذلك لما للمعلم من تأثير أساسي في عملية التعليم والتعلم . ماذا يجدي إذا ما طورنا مناهجنا، واحسنا مباني مدارسنا، وأكثرنا من الوسائل والتقنيات ،ولم نوفر المع
... Show MoreThere was a huge role in the history of a muslim woman and several books have mentioned that politically or in religion and even scientifically and socially which leaded a lot of women to look up to these women who helped in keeping the religion just in the right form for other generations
يتركز محور مشكلة البحث الحالي حول مفاهيم أساسية تعكس مكامن القوة في الشخصية الإنسانية وما لها من دور مؤثر على الواقع النفسي والمادي للفرد عموماً وهذه المفاهيم هي صلابة الشخصية، وتقدير الذات,ويتحدد مفهوم الصلابة من خلال مظاهر الشخصية وأسلوبها الذي تتميز به في التعامل مع الواقع وكيفية إدراكها وما تتمتع به من خبرات نفسية وتجارب حياتية داخلية تعكس مدى الوعي بالمستجدات الموقفية التي تصادفها
... Show MoreОдной из трудностей, вызывающих искажение смысла предложения, при переводе и понимании любых текстов зачастую является неправильное понимание функций и значений: союзов и союзных слов или замена одного значения другим. Это объясняется прежде всего тем, что при чтении основное внимание сосредоточено на переводе главных частей речи, на их многофункциональности и многозначности и упускаются из вида втор
... Show MoreChapter One
First, the importance of research and the need for him
Highlight the status of the nation and occupies a decent position among nations by what they offer for the good of humanity and tender, which is based mainly on the human and material wealth owned by the nation.
The investment of this wealth investment scientifically accurate based on the strong foundation that qualifies them to heights of glory, so stand out necessary development of all energies Alepeshriaaly the limit can not be considered as these energies fortune unless all elements of effective elements characterized by the positive interaction in various spheres of life and in the in
... Show MoreThe political system during the reign of Imam Ali (peace be upon him) was based on explicit openness in its features and objectives away from misinformation, and built its foundations and foundations on the Koranic legislation, and enacted by the Prophet (peace be upon him), and the decent legislation required by humanity
ان حماية البيئة وتخفيض التكاليف من األهداف التي تسعى الوحدات االقتصادية الى تحقيقها لكي تتماشى مع التوجه العالمي لحماية الموارد الطبيعية وإنتاج منتجات صديقة للبيئة وفي الوقت نفسه التخلص من االلتزامات التي تتحملها الوحدات االقتصادية من تكاليف بيئية وغر امات مما يؤدي الى ارتفاع كلف االنتاج ، يهدف البحث الى دراسة المرتكزات المعرفية الستراتيجية اإلنتاج األنظف وتحديد التكاليف التي يمكن تخفيضها خالل مراحل اا
... Show Moreاشتهرت بغداد بمساجدها ومأذنها ذات الطراز المتميز في التصميم والشكل والحجم والبناء والزخرفة. ونتيجة للاحتلال المتكرر والغزو الاجبي والكوارث الطبيعية الاخرى فان معظم ابنيتها تعرضت للتدمير والاندثار ولم يبق الا القليل منها شاهدا
The present study aims to explore determinants of entrepreneurial behavior from perspective of social theory. It is based on model notions of (Tyler & Blader, 2003) which have focused on studying role of positively personal and social identity in motivating employees to practicing desired behavior which serves the organization in which they work. Based on these notions and previous literature, study model were built. This model explains the relationship between status judgments (perceived internal respect and perceived external prestige) and entrepreneurial behavior. It includes three main hypotheses. The first and second hypothesis are concerning the relationship between status judgmen
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