The design, construction and investigation of experimental study of two compound parabolic concentrators (CPCs) with tubular absorber have been presented. The performance of CPCs have been evaluated by using outdoor experimental measurements including the instantaneous thermal efficiency. The two CPCs are tested instantly by holding them on a common structure. Many tests are conducted in the present work by truncating one of them in three different levels. For each truncation the acceptance half angle (θc) was changed. Geometrically, the acceptance half angle for standard CPC is (26o). For the truncation levels for the other CPC 1, 2 and 3 the acceptance half angle were 20o, 26o and 59o, consequently. A significant difference between the instantaneous thermal efficiency of 3.86× CPC (θc=20o) and 2.32× CPC (θc=26o), and between that for 3.61× CPC (θc=26o) and 2.32× CPC (θc=26o). It's noticed that the difference between the instantaneous thermal efficiency of 2.32× CPC (θc=59o) and 2.32× CPC (θc=26o) is small compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× CPC (26o) was higher than those for other three CPCs. The experimental results show that the maximum thermal efficiency of the full 2.32×CPC (26o) is 0.708, the maximum thermal efficiency of the 3.93×CPC (15o), when it's truncated to 3.84× CPC (20o), 3.61× CPC (26o) and 2.32× CPC (59o) are 0.51, 0.52 and 0.66, respectively. As the concentration ratio decreases from (3.93× to 1×), the thermal efficiency, energy losses and optical efficiency increase from (0.47 to 63), (1.58 to 7.2 K.m2/W) and (0.494 to 0.797), respectively.
الحمد لله رب العالمين والصلاة والسلام على سيد المرسلين أبي القاسم محمد (صلى الله عليه وآله وسلم ) وعلى آله الأطهار الميامين ، وصحبه الأبرار المنتجبين إلى يوم الدين 0
وبعد : فإن أجلّ ما بأيدي أبناء هذه الأمة القرآن كتاب ربّها ، الناطق بمصالح دينها ودنياها ، الذي جعله الله تعالى هدىً ورحمةً للعالمين ، وأنزله على خير خلقه من عباده محمّد الصادق الأمين ، وحث المسلمين على أتباعه ، وأمرهم على ل
... Show Moreالفلسفة السياسية وفلاسفتها دراسة في فكر الفيلسوف ليو شتراوس
يتناول البحث مدى المسؤولية المدنية المترتبة على وزارة الداخلية عن اعمال منتسبيها
اسلوب الحوار في القرآن الكريم اسلوب حياة وفي حقيقة الامر يضم القرآن الكريم بين دفتيه حوارات كثير مابين الله عزوجل وخلقه وما بين الانبياء واقوامهم وما بين الانبياء والطواغيت ومابين المؤمنين والكفار وهكذا ، وبدء الخلق قام على حوار مابين الله عزوجل وآدم وما بين آدم وابليس وما بيا الله جل وعلا والملائكة .
The phenomenon of substitution is one of the morphological phenomena mentioned in the Qur'an, where the researcher defined this phenomenon from the morphological and linguistic points of view and mentioned examples of it by citing references and sources
Play constitutes a significant means for children to figure out the world around. Play helps children to have a healthy brain that increase their creativity via developing emotional, cognitive, physical strength. Thus, the current research aims to identify the role of play in psychological development of children. The findings of study revealed that play develops children’s cognitive, emotional abilities and enhances their self-confidence. Play forms a major approach for learning that promotes children to get rid of stress. Additionally, it supports language development of children
The Arab woman expressed the life of oppression that she suffers from in her masculine environment, as she expressed her linguistic abilities with eloquence and intelligence, as she did not neglect philosophy, wisdom, and exhortation
هدف الدراسة معرفة التأثير السمي التراكمي للأعلاف الملوثة بالحنطة المتفحمة على أفراخ فروج اللحم .اجري هذا البحث في مختبرات الصحة الحيوانية التابعة لوزارة العلوم والتكنولوجيا استعمل 78 فرخاً لهذه التجربة قسمت إلى ستة مجاميع ربيت في أقفاص خاصة أعدت لهذا الغرض. تم تغذيتها يوميا على أعلاف ملوثة حسب برامج التغذية المتبعة , تمثلت المجموعة الأولى بمجموعة السيطرة والتي غذيت على عليقه تحوي الحنطة
The Arab woman expressed the life of oppression that she suffers from in her masculine environment, as she expressed her linguistic abilities with eloquence and intelligence, as she did not neglect philosophy, wisdom,