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%.
After atour-For quite somtime,in the field of research and investingation on the economic aspects and the impact of her money is mportantin the evolution and emegece of the Islamic countres,especially including especially Morkhana him specimer nigh borhood the countries of the mashreq al islami,searhout,among other things summarilesas
لكل دولة في هذا العالم خطابها السياسي والذي يحدد سياستها الداخلية والخارجية، وهي سياسة ثابتة تنطلق من مفاهيم وبرامج وثوابت تخدم مصالحها الحيوية، لكون الخطاب السياسي ليس مجرد كلام عابر في عالم السياسة الدولية وانما هو ثوابت مهمة يحدد توجهات هذه الدولة او تلك ويحدد دورها الدولي وطبيعة العلاقة مع البلدان الاخرى ومنها الدول المجاورة لها. شهد العراق بعد العام 2003 تحديات جديدة تمثلت بتغليب خطابات الطائفية والكراه
... Show MoreThe objective of the research is to find the best method to estimate rice crop through out evaluating the applied methods of stratified random sampling .By using different sorts of sampling estimators, a comparison was held among the variances of the mean for simple random sampling, stratified random sampling(var()) and separate regression estimator. The results indicate that the separate regression estimator give best estimations. The approximate cum.f4/5 method was used to determine the optimum stratum boundaries, new strata was put and then var () was calculated .In comparison with strata used nowadays in central statistical organization, the new strata led to obvious decrease in the variance. The stratified mean wa
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The current research aims to determine the relationship of the impact of the components of the financing structure, especially financing through debts, as well as the earnings per share in the value of the shares of companies listed in the Iraq Stock Exchange. The research sample and identifying the strength of the combined effect of the ratio of financing through debt and earnings per share in maximizing The market value of the firm and the real value, as well as the variation between these relationships according to model of the real value of the companies and the market value of the research sample companies. The research community is represented by the Iraq Stock Exchange, while a conditional deliberate sample
... Show MoreLanguage contains various kinds of grammatical rules that are used to express thoughts and feelings. The present paper studies some of the German language grammatical rules as being the most important basics needed to master and develop the art of writing for the German language learners. Writing is one of the productive language learning skills that transform thoughts into a written form. Hence, constant exercising on the use of the language to master the grammatical rules enables German language learners to develop their creative writing skills.
The present study discusses the importance of grammatical exercises in developing the language learning abilities. The study provides a gener
... Show MoreAbook of alzmkchri (AL-Mefsal) considers one of the most book familiarities among grammarians whom begin to explain it importance kitab AL-Takhmair for Khwarizmi separated opinions in grammatical schools that dealt with.
Abstract
The distribution is one of the elements of the marketing mix key by which companies can to deliver their products through private channels to all customers in right time and right place to check though in which the levels desired by customer satisfaction, the and purpose of the discussion dealt with the preparation of analytical studies to explain the impact of live performance of distribution channels in achieve customer satisfaction in industrial companies, as well as the diagnosis and the reality of the research variables in companies under study and describe the kind of relationship between changers Home on the one hand and the relationship between the variables sub on the other hand, represe
... Show MoreThe effect of 5555 strategy on reading comprehension among 4th preparatory students Assist. Prof. Dr. Hassan Khilbas Hammadi College of Education Ibn Rushd – The University of Baghdad Assistant Lecturer. Waleed Khaled Talib Directorate – General For Education Province Of AL - Anbar The purpose of study is to identify the effect of 5555 strategy on reading comprehension among 4th preparatory students. To do this, null hypothesis was postulated. The author hypothesize that there is no a statistically significant difference at (0.05) level between experimental group's scores who study reading comprehension subject following the 5555 strategy and control group's scores who study the same subject following the traditional method in readin
... Show MoreThe importance of teaching methods and procedures comes from the nature and significance of the questions raised inside the classroom. That is, because questions, in fact, are the means of communication and interaction in the class situation. Therefore they are considered as indispensible elements in any teaching approach. Furthermore, it is noticeable that the majority of teachers fail in using them, for questions are often casted spontaneously and without pre-planning. Hence, a delay may occur in realizing the pre-set objectives, and let alone the dominance of stereotyped questions, especially when the teachers focus on a type of question which can be directly answered from the text-book.
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... Show Moreتهدف هذه المقالة إلى توضيح أخلاقيات العلم وضوابطه التي يجب على من يعمل في هذا المجال أن يكون متحلي بها حتى يحافظ على القيم والأخلاق الفاضلة والموروثة من الآباء والاجداد والنابعة من الصالحين والاخيار لديم ومة الحياة بأفضل وجه وكما يتمناه الكل وكذلك عدم تجاوز الحدود التي تؤدي إلى الأض ا رر بالمجتمع والبيئة . وتوضيح الحدود الغير مسموح بتجاوزها في مجال العلم والتكنولوجيا ومن هذه الأخلاقيات أو الضوابط التي يجب أن
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