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%.
Si Alfonso x el sabio y la Escuela de Traductores de Toledo habia hecho del castellana una lengua apta para la expresión cientifica, fue Pablo Neruda quien aplicó su sentido artistico para crear una poesia amorosa de caracter lileraria. Por lo tanto, pocos poetas han llegado ton populares come. Pablo Neruda, en el mismg tiempo: se comsidera esccitor de una abundante producción literaria ne sólo en su ciudad natal de (Chile), Sino ha sida uno de los padres de la poesia hispanoamericana contemporónea. Ademas la influencia que ejerció en el grupo de poetas de la Generación del 27, con los que empezó a relacionarse durante su estancia en Madrid, fue decisiva también para la poesia espańola. Esa era la razon principal que me hizo pe
... Show Moreدور الحكومات في بناء الدولة ضمن اطار الدستور
The mihrab is an architectural element created by the Muslims for the necessities of which the direction of Qibla is set in the mosques, and the front stands in it during the prayer so as to provide a complete description of the Muslims inside the chapel. The mihrab has a third benefit in amplifying the voice during the time of prayer, Peace be upon him) and the Mosque of Damascus, the Mosque of Kairouan, and the Mosque of Amr Balfstat?.
واقع ومستقبل الصراعات الدولية والاقليمية في البحر الاحمر
اثر المحددات الخارجية والداخلية في بناء الدولة العراقية
Jean-Paul Sartre est la figure principale de l’existentialisme au XXe siècle et spécialement à partir des années cinquante. En partant du travail dans les lycées dans les années trente comme professeur de philosophie, passant par la guerre qui l’obligeait à rester comme témoin passif jusqu’à de l’après guerre avec la naissance de l’existentialisme, Sartre déploie tous ses efforts pour une référence intellectuelle majeure sur tous les fronts: littéraire, philosophique et politique. Dans tous ses livres Sartre aborde le statut de la littérature des idées et de l’écrivain dans la société. Il apparait comme un réactionnaire qui cherche à « régler ses comptes avec le milieu bourgeois dans leq
... Show MoreThe study aims to identify the students’ attitudes toward recent techniques’ use in teaching; using power point software and data show to facilitate teaching approaches as well as following the approach of lecture in giving subjects, do these techniques facilitate, increase, and tackle the difficulties of subjects, do these attitudes positive or negative?, and to what extent these techniques raise up students’ motivation.
The internationalization of the Libyan crisis and its accompanying militarization of the conflict have played a vital role in hindering to reach a comprehensive political settlement solution in Libya. The increasing international greediness in the Libyan energy resources and the geopolitical importance of the Libyan State led to the involvement of many international and regional powers in this crisis and transformed the Libyan crisis into “proxy war”. Moreover, the Turkish direct military intervention in the Libyan crisis is considered as one of the main constraints facing the international and regional efforts to settle the Libyan crisis as a result of the Turkish insistence on its military existence in Libya to preserve i
... Show MoreIf the syntactic structure is a reflection of what is in the mind of the creator of synergies
نالت الحياة الادبية في مملكة غرناطة الاندلسية حظاً كبيراً