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.
يعد التعلم النشطعملية نشطة ذهنية يبذٌل بها العقل الجهد الكافي لإِكتشاف المعرفة فالمعلمليس ناقلاً فيه للمعرفة ،) وانما مرشداً وموجهاً والمتعلم محور العملية التدريسية فيه،إِي عمليةإِبداع يختار منها المعلمما يستطيع الابداع فيه وتركيبه)حارص، 2015:6 والتعلم النشط طريقة تعاونية يشترك فيها جميع المتعلمين بالأنشطة والواجبات المتنوعة التي تسمح لهم بالأصغاء الإِيجابي والتحليل السليم للمادة والتفكي ا رلابداعي اذ تت
... Show Moreالملخص: لتحقيق أهداف البحث قامت الباحثتان ببناء مقياس للتفكك الاسري اعتمادا على نظرية (باندورا) وتكون بصورته النهائية من (24) فقرة ، وطبق المقياس على عينة البحث البالغة (150) تلميذ وتلميذة تم اختيارهم بالطريقة العشوائية البسيطة من مجتمع البحث ،وبعد جمع البيانات تم معالجتها باستعمال الوسائل الإحصائية منها الاختبار التائي، وتحليل التباين الرباعي والاختبار الفائي، وتوصل البحث الى النتائج الأتية :ان أفراد عينة ال
... Show MoreThis research aims to measure the impact of applying bank governance mechanisms in reducing the financial risks of banks listed on the Palestine Stock Exchange, and to answer research questions and test hypotheses for the study, researchers adopted the descriptive and analytical approach, and data were collected from the annual financial reports of the banks listed on the Palestine Exchange during the period between (2009-2018), as a time series for the purpose of finding, analyzing and measuring the effect between the study variables during this period by (60) views for each of the study variables, using the statistical analysis program views(9) to enter, process and analyze the data. The results of the study proved that there i
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ناولت هذه الدراسة إحدى الشخصيات الأمريكية التي تأثرت بواقع السود. كان بوكر تاليافيرو واشنطن أحد الأمريكيين السود ، الذين ولدوا في ظل العبودية وتعرضوا للاضطهاد بعد إلغاء حقوق التصويت وإطلاق قوانين جيم كرو من قبل الولايات الجنوبية. ورأى واشنطن خلال عمليات إعادة الإعمار أحوال السود وكيف كانت معاناتهم قبل الحرب الأهلية في ظل ظروف العبودية التي شملت الإذلال ، والحرمان من حقوقهم المدنية والسياسية، فيما لم يختلف
... Show Moreهدفت الدراسة الحالية التعرف على البلادة العاطفية لطلبة الجامعة وكذلك التعرف على معنوية الفروق في البلادة العاطفية تبعاً لمتغيري: النوع (ذكور-اناث) والتخصص الدراسي (علمي –انساني) ، تآلفت عينة الدراسة من (400) طالب وطالبة موزعين بالتساوي حسب النوع والتخصص الدراسي تم اختيارهم عشوائيا من طلبة الجامعة، استخدمت الباحثة مقياس البلادة العاطفية من (اعداد الباحثة) وبعد تطبيق المقياس على عينة البحث واستخراج البيانات با
... Show Moreobjective of this research is to identify some of the obstacles that face secondary school teachers of the Arabic language courses in using modern teaching methods in class.
The research focuses on secondary school teachers of the Arabic language courses at the central region of Nineveh Governorate for the school year (2008-2009). 30 teachers out of 792, were randomly chosen to apply the research tool upon.
To fulfill the objective of this research, the researcher first surveyed a number of teachers , he then identified four categories of obstacles; obstacles related to school administrative system and environment, the teacher, courses and pupils, and the nature of teaching method
... Show MoreThe research aims to measure, assess and evaluate the efficiency of the directorates of Anbar Municipalities by using the Data Envelopment Analysis method (DEA). This is because the municipality sector is consider an important sector and has a direct contact with the citizen’s life. Provides essential services to citizens. The researcher used a case study method, and the sources of information collection based on data were monthly reports, the research population is represented by the Directorate of Anbar Municipalities, and the research sample consists of 7 municipalities which are different in terms of category and size of different types. The most important conclusion reached by the research is that there is a variation in the efficien
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