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Article
A Dynamic Modeling Capability for Subcritical Vapor Compression Refrigeration System
تطویر نموذج دینامیكي لدورة البخار اللانضغاطیة لمنظومات التثلیج

Authors: Jafar M. Hassan --- Ali H. Tarrad --- Mohammed N. Abdullah
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2009 Volume: 27 Issue: 13 Pages: 2319-2338
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In this investigation the individual component models for a typical subcritical cycle are developed based on the best published theoretical and empirical literature. The developed approach, especially for air conditioning systems, is conceptually new and can be used with modification to a variety of multicomponent system applications. The component models are then integrated and the model predictions validated against the data from various experimental test systems.A variable speed compressor test rig was used to obtain the experimental data to be compared with the results predicted from the system model. The experimental data was monitored from the start-up of the system until the achievement of its steady-state. The system approached its steady-state after 270 sec and 360 sec for compressor speeds of 900 rpm and 1200 rpm respectively. The system disturbance was imposed by changing the operation conditions for each component. A comparison between the experimental data for these disturbances and theoretical results shows a good agreement with a discrepancy ofabout (5%). The model can be used as a basis for the design, performance and efficiency of a vapor compression systems.

في هذا البحث تم إعداد النموذج الرياضي لكل معدة من دورة التثليج الانضغاطيةاستنادا الى أفضل النشريات من البحوث النظرية والتجريبية وخاصة بالنسبة لمنظومات تكييف الهواء. ويمكن استخدام هذه النماذج مع بعض التعديلات في المنظومات متعددة المكونات. وثم تم تجميع النماذج الرياضية لكل معدة في نموذج رياضي متكامل وتم مقارنة النتائج النظرية مع نتائج التجارب العملية. تم استخدام منظومة تثليج ذات ضاغطة متغيرة السرعة لغرض الحصول على القراءات العملية ومقارنتها مع النتائج المستحصلة من النموذج الرياضي. أخذت القراءات عند تشغيل المنظومة لغاية حصول حالة الاستقرار للمنظومة ، حيث أجريت التجارب عند سرعة الضاغطة 900 دورة/دقيقة وجد إن الزمن اللازم لحصول حالة الاستقرار 270 ثانية ، بينما الزمن اللازم لحصول حالة الاستقرار 360 ثانية عند سرعة الضاغطة 1200 دورة/دقيقة . بعد ذلك تم تغيير ظروف التشغيل لكل معدة على حدة مع الإبقاء على الظروف التشغيلية لباقي المعداتدون تغيير، وتمت مقارنة النتائج العملية والنظرية حيث لوحظ هناك توافق جيد وبنسبة خطأ 5% . إن النموذج الرياضي يمكن استخدامه في تصميم وتحديد معامل الأداء وكفاءة منظومة التثليج الانضغاطية.


Article
Competitive Adsorption of Furfural and Phenolic Compounds onto Activated Carbon in Fixed Bed Column

Authors: KAWTHER W. AHMED --- ABBAS H. SULAYMON
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2007 Volume: 13 Issue: 3 Pages: 1721-1736
Publisher: Baghdad University جامعة بغداد

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Abstract

For a multicomponent competitive adsorption of furfural and phenolic compounds, a mathematical model was built to describe the mass transfer kinetics in a fixed bed column with activated carbon. The effects of competitive adsorption equilibrium constant, axial dispersion, external mass transfer and intraparticle diffusion resistance on the breakthrough curve were studied for weakly adsorbed compound (furfural) and strongly compounds (parachlorophenol and phenol). Experiments were carried out to remove the furfural and phenolic compound from aqueous solution. The equilibrium data and intraparticle diffusion coefficients obtained from separate experiments in a batch absorber, by fitting the experimental data with theoretical model. The results show that the mathematical model includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for furfural and phenolic compounds in fixed bed adsorber.


Article
Efficient Synthesis of highly new substituted Imidazoles starting from Benzil using KMnO4 as an efficient catalyst

Authors: Hassan A. Jaraf --- Basil Abdulmahdi Saleh --- Ali Hashem Issa
Journal: Journal of Basrah Researches (Sciences) مجلة ابحاث البصرة ( العلميات) ISSN: 18172695 Year: 2019 Volume: 45 Issue: 2A Pages: 262-278
Publisher: Basrah University جامعة البصرة

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Abstract

Reaction of Benzil with an aldehyde, 4-trityl aniline and NH4OAc under reflux gave highly substituted imidazoles in good yields using accessible and nontoxic KMnO4 as catalyst under mild reaction conditions. This method is simple, efficient and eco-friendly. All imidazoles were characterized using FT-IR, Mass spectrometry, 1H-NMR and 13C-NMR Nuclear magnetic resonance spectral techniques.


Article
On Shrinkage Estimation for R (s, k) in Case of Exponentiated Pareto Distribution

Journal: Ibn Al-Haitham Journal For Pure And Applied Science مجلة ابن الهيثم للعلوم الصرفة والتطبيقية ISSN: 16094042/ 25213407 Year: 2019 Volume: 32 Issue: 1 Pages: 147-156
Publisher: Baghdad University جامعة بغداد

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Abstract

This paper concerns with deriving and estimating the reliability of the multicomponentsystem in stress-strength model R(s,k), when the stress and strength are identicalindependent distribution (iid), follows two parameters Exponentiated Pareto Distribution(EPD) with the unknown shape and known scale parameters. Shrinkage estimationmethod including Maximum likelihood estimator (MLE), has been considered.Comparisons among the proposed estimators were made depending on simulation basedon mean squared error (MSE) criteria.

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