A paraffin wax and copper foam matrix were used as a thermal energy storage material in the double passes air solar chimney (SC) collector to get ventilation effect through daytime and after sunset. Air SC collector was installed in the south wall of an insulated test room and tested with different working angles (30o, 45o and 60o). Different SC types were used; single pass, double passes flat plate collector and double pass thermal energy storage box collector (TESB). A computational model based on the finite volume method for transient tw dimensional domains was carried out to describe the heat transfer and storage in the thermal energy storage material of collector. Also, equivalent specific heat method was employed to describe the heat storage and release in the mushy zone. Experimental results referred to an increase in thermal conductivity of paraffin wax that supported by copper foam matrix more than ten times. While the ventilation effect was still active for hours after the sun set, depending on the heat storage amount. Maximum ventilation mass flow rate with TESB collector was recorded with value equals to 36.651 kg/hr., when the overall discharge coefficient that was calculated for the system equals to 0.371. Experimental results showed that the best working angle range was 45~60o, and the highest air to the collector approaching temperature appeared to the double passes flat plate collector. Results gave greater heat storage efficiency of (47)% when the maximum solar radiation was 780 W/m2 at 12.00pm, while the energy summation through duration charge time was 18460 kJ. Computational results, depending on the equivalent heat capacity method for heat storage or release from phase change material that supported by copper foam matrix, showed the behavior of paraffin wax melting and solidification situation through periodic for charge and released heat from the solar collector. Also, these results gave agreement approaching the experimental results for the heat storage in the combined heat storage material, with standard error of 16.8%.
Praise be to Allah , the Lord of Heavens , Who revealed His Scripture in plain Arabic, and prayers and peace be upon the Master of all creatures and the chosen one , Muhammad (PBUH).Pushkin was known as a poet in Russia, the sun of its poetry that set, the father of the Russian literature and the founder of its literary language. When he published his poems, trying to express his inner poetic feelings and creative visions, he presented them with creativity and special touch. The reason behind the selection of Pushkin as the subject of this study is that he was affected by Islam and Arabs. For the purpose of this study, the dissertation has been divided into introduction and three chapters; each chapter includes two topics. In the introdu
... Show Moreهمجوارى جغ ا رفياى ميان عربها واي ا رنيان نقش بز رگ در بروز آشكار برخى از روابط وعلاقه
هااى مياان دو زباان عرباى وفار اى وهمچناين مياان دو ادبيااا عرباى وفار اى وگويناد كاه ادبيااا
فار ى قديم اولين ادبياا خارجى كاه باه ادبيااا عرباى مبوا، باود وهماين باعا انبشاار زباان عرباى
در اي ا رن شد. وبعد از فبح ا لامى زبان فار ى بيشبر وا ه ژ هاى خود از زبان عربى گرفاا همچناين
به زبان عربى ب يارى از وا ه ژ هاى وادر كرد
يناقش هذه البحث فكرة الهوية الوطنية العراقية عند الإمام محمد تقي الشيرازي، والوقوف على دراسة سيرته الذاتية والعلمية، وتحديد مواقفه السياسية، ورؤيته لفكرة الهوية الوطنية العراقية، من خلال البحث والتحليل لأبرز مواقفه ورسائله وافكاره السياسية.
Abstract
The current research aims to know the reality of the research's coefficients, to know correlation and effectiveness between the organizational Agility and high performance . The current research has been applied on the official banks , including a sample of senior administration members (120) ; besides , the research has used questionnaire that being considered as the main tool for gathering information and data . It includes 59 questions in addition to the personal interviews program as to support the questionnaire and to fulfill a great deal of reality. It has been anal
... Show Moreمكانية استخدام السوق المالية في التنبؤ بالدورات الاقتصادية
انطلاقاً من ضرورات التجديد والتطوير لمجلتنا العزيزة، ستجرى اضافات عليها بين الحين والآخر، قد تتناول شكلياتها و/ او محتوياتها. والبداية ستكون بترجمة المقالات والبحوث التي تقع في اختصاصها من المجلات الاجنبية المرموقة عالمياً، فإختارت هيئة التحرير المقالات الخمسة التي سيرد ذكرها لاحقاً للقيام بترجمتها بأسلوب علمي يعطي للتصرف والاضافات حدوداً لتصبح مقبولة وسهلة على القراء. فالمهمة هذه وان كانت صعبة وتت
... Show Moreتعد دراسة الموارد الماءية السطحية من المواضيع المهمة وذلك لكثرة السكان وازدهار استهلاك الإنسان لمياه الشرب وفي مجال الشرب والزراعة والصناعة وكثرة الملوثات في المياه وكيفية معالجتها
Economic life in any of the countries depends mainly on economic activity due to its great role in meeting the needs and expenditures of the state . therefore ، Bahrain played a major role in commercial exchange operation ، whether at home or abroad . whatever the matter
لقد شهدت المنطقة العربية تحولات وتغييرات شاملة انطوت على عنصري المفاجأة من حيث التوقيت، وانعكاساتها الاقليمية والدولية، إذ اجتاحت الدول العربية ثورات شعبية احدثت جملة من التغيرات والتبدلات الجيوسياسية، اذ استطاع بعضها اقتلاع انظمة حاكمة كان من غير المتصور ان تتزحزح من مكانها مع تسلحها بكل ادوات العصر من القمع والديكتاتورية الاستبداد، لذا كان للطابع الشعبي السلمي والنجاح الذي تحقق للشعوب العربية كما في م
... Show MoreThe research aims to explain the role of the flexible budget in assessing the feedback resulting from deviations by comparing the actual results with the planned performance in light of the economic crisis that the world witnessed during the spread of Corona disease. As most companies, including the Electronic Industries Company, face the problem of controlling production costs and are trying hard to reduce these costs to the lowest level starting from measuring these costs and allocating them and distributing them to products. This helps in controlling deviations and thus the flexible budget becomes a tool that helps in controlling elements Costs