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.
The upbringing of Yehuda Amichai and the conditions he lived in had a great influence on his deep sense of pain, which made him think of death and suicide. Especially after the Nazis came to power in Germany, and his emigration with his family. Amichai searched for love throughout his life, and his failure was one of the most important factors affecting his psyche, which is A deep influence that made him live in harsh and painful pains that broke him, and prevented her from achieving his ambitions in life.Dramatic texts are characterized by repetition in writing and presentation. It is a textual discourse that has two advantages, first, that it can be read as a literary text like all other literary texts, and second, that it can be consider
... Show MoreThe commercial job is one of the most important businesses in the cities as there is no city can exist without commercial markets to offer service to its inhabitants. This study aims to distribute the commercial function in Abu Tayara Street located in the municipality of Al-Dora by highlighting the size of such businesses in this street. It focuses on analyzing the change that has occurred due to the usages of the commercial land not only in the residential areas, but also in various aspects associated with the growth of the population in the city. Both expansion and development of the economic and social aspects in the area have increased the demand for commercial services. So, the research focuses on the aspects of functional speciali
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Praise be to God, who created people from one soul, and made her husband, and prayers and peace be upon His Messenger, Mercy given and the grace given, and on a machine and companions pure. Divorce cases have increased in recent years in a worrying manner, especially since divorce has unforeseen consequences at the individual and social levels. The source of concern stems from the fact that the cohesion and integrity of society starts from a family as it is the cornerstone of the social structure, which is the foundation upon which the large society is based. Marital life may suffer from problems and obstacles that are difficult to solve, so the man presents the divorce of his wife and that the phenomenon of divorce is not a result of it, b
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The current research aims to measure the level of entrepreneurial orientation and its dimensions (creativity, independence, proactivity, risk tolerance, and achievement) in the National Security Chancellery, as its importance and role in guiding senior leaders of the chancellery to make strategic decisions with high quality in various Iraqi concerns, more specifically the security aspect. The data was collected from 94 individuals (the research sample) from the research community (120) individuals at different administrative levels and intentionally where the questionnaire was adopted as a main tool for data collection and the primary data was analyzed through descriptive and inferential statistical methods (arithmetic mean, standard dev
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