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%.
The aim of this research is to make a new investigation of a scientific thesis in Arabic Morphology in which an allusion occurred in relation to its real author and its title, there is alot of dropping and flaw when it was first applied due to depending on one written transcript
Problem: Find dimensions of the problem by answering the following question: what the effect of using the Six Thinking Hats strategy to acquire the historical concepts and retain the fourth-grade students in the subject of literary history. Importance of research: current research is gaining importance in many ways, including: 1. Keep pace with the new in the field of education and modern educational strategies. 2. Shed light on innovative education strategy in the teaching of history, which is one of the materials that need to renew the tragedy of instruction methods for students. 3. Out of the monotony and traditional way of teaching to a method and a new strategy to develop the teacher and the learners thinking skills through various
... Show MoreThe wastewater arising from pulp and paper mills is highly polluted and has to be treated before discharged into rivers. Coagulation-flocculation process using natural polymers has grown rapidly in wastewater treatment. In this work, the performance of alum and Polyaluminum Chloride (PACl) when used alone and when coupled with Fenugreek mucilage on the treatment of pulp and paper mill wastewater were studied. The experiments were carried out in jar tests with alum, PACl and Fenugreek mucilage dosages range of 50-2000 mg/L, rapid mixing at 200 rpm for 2 min, followed by slow mixing at 40 rpm for 15 min and settling time of 30 min. The effectiveness of Fenugreek mucilage was measured by the reduction of turbidity and Chemical Oxygen Demand
... Show Moreاهمية البحث هي مرحلة نمو وبناء اجهزة الجسم للاعبين الاشبال واعداد تدريبات بأسلوب التدريب الدائري لبناء التحمل لتطوير بعض القدرات الحركية والمهارية لدى اللاعبين الاشبال بكرة القدم , حيث لاحظت الباحثة ضعف في مستوى الاداء الحركي ارتأت اعداداً بدنيا ومهارياً منذ مرحلة البناء الأولى للاعب الفئات العمرية , واستخدم الباحث المنهج التجريبي بالاختبار القبلي والبعدي للمجموعتين التجريبية والضابطة لملائمته لطبيعة ال
... Show MoreThe research has focused on accounting for marketing risks faced by banks because they are exposed to a high level of risk as a result of their great utilization of financial instruments, which may make them liable to insolvency or bankruptcy and collapse, and accordingly to major economic crises. Therefore, banks are required to manage (reduce) risks so as to prevent them. As Iraqi banks don't manage these risks according to modern methodology of using derivatives, as well as lack of both the standard accounting system for banks and the Iraqi accounting criterion (standard) No. 10 to an obvious methodology for these risks identification, classification, hedging and disclosure, the researchers was prompted to concentrate
... Show Moreتتطلب كرة القدم الحديثة تطوير الصفات البدنية والمهارية للوصول باللاعب إلى لمستويات العليا، ولما كانت هذه الصفات مرتبطة مع بعضها البعض، فانها تتطلب ان يتم تطويرها معا في نفس الوقت دون تنمية كل صفة على حده، وإن توافر الحد الأدنى من الصفات البدنية كمتطلبات أساسية للأداء المهاري يعتبر الهدف الأساسي للتخطيط لأي برنامج تدريبي، وإن الصفات البدنية لها مفهوم شاسع وواسع الاستعمال في مجال البحوث الرياضية، وقد أعطيت ع
... Show MoreGrowing interest in the subject of corporate governance after the repercussions of financial collapses of some of the leaders of American companies and European, and the consequent crisis of confidence in global financial lists of companies due to weak accounting disclosure and transparency, was quick from many countries and international organizations to adopt the concept in an attempt to improve the situation of companies and promote transparency and prevent further financial crises in the future. Based on this background, the present study aims to shed light on the concept of exercising the powers of governance that has become invitations for adoption in Iraq of great importance, given the increasing role of corporations both restrict
... Show MoreIn this paper, Nordhaus-Gaddum type relations on open support independence number of some derived graphs of path related graphs under addition and multiplication are studied.
Laser etching may be an alternative to acid etching of enamel and dentin. Several characteristics of irradiated dental hard tissues have been considered advantageous, microscopically rough surfaces without demineralization, open dentinal tubules without smear layer production and dentin surface sterilization. The aim of this study is to determine and compare histology the microleakage in class V cavity restored with a light cured composite after conditioning the samples(tooth surface) with 1-acid etching, 2-Q-switched Nd:YAG Laser etching and finally 3- acid and laser etching. Materials and methods: Twenty four non carious human extracted teeth were used in this study. The samples were equally grouped into four groups of six teeth each.
... Show MoreSocial protection meets different aspects of the needs of vulnerable groups, such as the economic, health, education, and family relations and ties in the Iraqi society. This is because vulnerable groups have suffered from social and economic influences that have negative implications on the social reality as a whole. Poverty is a case in point, which paved the way to frequent setbacks that have led to social structure instability. Accordingly, the present study aims to examine the role and effect of the Net of Social Protection Program in equally distributing social protection to curb or mitigate any negative consequnces that might happen to the poor segments and vulnerable people, who are succeptible to shocks, such as: the orphans, un
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