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%.
Abstract
This research aims to assess the practice of physical activities by people with intellectual disabilities and its challenges during the Coronavirus (COVID-19) pandemic from their families' point of view. The research sample consisted of (87) individuals from families with intellectual disabilities in the Makkah region. The sample was selected by the simple random method where the researcher used the descriptive analytical approach. A questionnaire of (32) items was used as the research tool to collect data. The findings of the study showed that the assessment level of practicing physical activities by people with intellectual disabilities was low. The public facilities dimension ranked first with a moder
... Show MoreOne of them one of the important books due to its containing valuable information written by the author. Information include the life of the Messenger (Peace be upon him) before and during the mission and what happened to the messenger and his adherents and faithful companions (May Allah be pleased with them all)
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
The Dictionary of Countries by Yaqut al-Hamawi is one of the most important sources that researchers rely on in everything related to geography in knowing the names of places and countries, and the important historical information it contains about different cities and countries
Gompharena globosa L., Irisene herbistii Hook. ex Lindl. The results of this study showed that the anatomical characters of the stems epidermis and the indumentum covering different parts of the plant have an important anatomical characters such as the cell wall shape of ordinary epidermal cells also the shape and type of stomata, their presence in some taxa and abscent in others. The hairs also differentiated by their shapes and them types, either they glandular or eglandular also they are different in distribution between the different taxa or in the some taxon.
One of them one of the important books due to its containing valuable information written by the author. Information include the life of the Messenger (Peace be upon him)
This research work dealt with the problem of layout the production line of engine of fan roof at the General Company for Electrical Industries (GCEI). It was observed that the assembly line of engine was unstable and subject to severe fluctuations. In addition the execution of tasks at some stations was observed to be very fast while at other stations was slow. This phenomenon resulted into bottlenecks between workstations, idle time, and work in process. The system design was used to assign tasks to work stations according to different heuristics (Ranked Positional weight techniques, longest Task Time, Most following tasks, Shortest tasks time, Least number of following task).
The study revealed that th
... Show Moreيهدف البحث لمحاولة دراسة واقع ادارة الوقت لدى عينه من رؤوساء الأقسام العلمية في كليات ومعاهد هيئة التعليم التقني اذ بلغ حجم العينة (47% ) فرداً تم احتيارهم عشوائياً من (15) كلية ومعهد موزعة في (69 من محافظات القطر وبلغ حجم عينة البحث (17%) من عدد رؤوساء الاقسام العلمية في الهيئة ، ولغرض جمع البيانات تم أعداد استمارة استبيان تمت صياغتها بشكل يؤمن توثيق الوقت الفعل
... Show MoreProblem: 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
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