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Article
NUMERICAL SIMULATION FOR HEAT TRANSFER ANALYSIS IN LAMINAR FLOW OF CuO-WATER NANO-FLUID IN TUBES
النمذجة العددية لتحليل انتقال الحرارة للجريان الطباقي لمائع متناهي الصغر (اوكسيد نحاس-ماء) في الأنابيب

Authors: Dr. Emad Abdula Khazal د. عماد عبدالله خزعل --- Dr. Khalid Baker Saleem د. خالد بكر سليم
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2017 Volume: 10 Issue: 1 Pages: 87-102
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

This paper presents a two-dimensional numerical analysis to study the laminar heat transfer and flow characteristics of CuO–water nanofluids through a tube at constant heat flux boundary condition at tube wall. Based on the single-phase approach, the effects of different parameters such as nanoparticle volume concentration (1% - 5%), and Reynolds number (500 - 2100) for various axial locations of tube with CuO–water nanofluids as working media were discussed in detail. The finite volume method and SIMPLE algorithm are utilized to solve the governing equations numerically. The numerical results shows that with enhancing Reynolds numbers, local Nusselt number increases. The variations of the local Nusselt number relative to volume concentrations are not uniform. According to the results, an equation was obtained for Nusselt number predicted data using the dimensionless numbers. The relation between local Nusselt number and Re number also compared for other previous work. There are agreement in results and found the maximum difference between results reach to be 6.3% approximately which validate the current computational model.

في هذا البحث تم دراسة الحل العددي لنموذج ثنائي البعد لجريان طباقي وانتقال الحرارة لمائع متناهي الصغر لخليط من الماء و اوكسيد النحاس (مائع نانوي) خلال الأنابيب معرض إلى فيض حراري ثابت على الجدران.استنادا إلى طريقة المائع الواحد تم دراسة تأثير عدة موثرات من ضمنها نسبة حجم المائع النانوي (1% - 5%) ورقم رينولدز (500-2100) على طول جريان الأنبوب مملوء بخليط من الماء واوكسيد النحاس. تم حل المعادلات الحاكمة باستخدام طريقة الحجوم الصغيرة و صيغة (SIMPLE) كطريقة عددية. ظهرت النتائج بزيادة رقم ينولدز (Re) يزداد معدل انتقال الحرارة وكذلك بزيادة النسبة الحجمية للمائع النانوي. استناداً إلى النتائج المستحصلة تم التنبوء بمعادلة بين رقم نسلت (Nu) وجميع الأرقام اللابعدية. أيضا تم مقارنة النتائج لرقم سنلت ورقم رينولدز متعدد مع عمل سابق وكان هناك توافق بين النتائج وأقصى فرق في النتائج يصل إلى 6.3% تقريبا، مما يؤكد موثوقية النموذج الحسابي الحالي.


Article
Laminar Mixed Convective Nanofluid Flow in a Channel with Double Forward-Facing Steps: A Numerical Simulation Study

Author: Omar A. Hussein
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2017 Volume: 24 Issue: 1 Pages: 38-49
Publisher: Tikrit University جامعة تكريت

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Abstract

Predictions are reported for mixed convection using various types of nanofluids over forward-facing double steps in a duct. The continuity, momentum and energy equations are discretized and the simple algorithm is applied to link the pressure and flow fields inside the domain. Different types of nanoparticles Al2O3, CuO, SiO2 and ZnO, with different volume fractions in range of 1-4% and different nanoparticles diameter in the range of 20 – 80nm in base fluid (water) were used. Numerical investigations are conducted using finite volume method. In this study, different parameters such as the geometrical specifications (different steps heights in the range of h1= 0.01m-0.04m and h2 = 0.03m-0.06m for FFS) are used. Different Reynolds numbers in the range of 50-2000 (laminar flow) are investigated to identify their effects on the heat transfer and fluid characteristics. The results indicate that SiO2-water has the highest Nusselt number followed by -water, -water and ZnO-water. The Nusselt number increases as the volume fraction increases but it decreases as the nanoparticles diameter increases. The velocity magnitude increases as the density of nanofluids decreases. The recirculation region and the Nusselt number increase as the step height, Reynolds number, and the volume fraction increase.


Article
An Experimental Investigation on the Performance Enhancement of Photovoltaic/Thermal Panel Using a Tracking System and Nanofluid (Al 2O3)

Authors: H.A. Hussein --- A.H. Numan --- A.R. Abdulmunem
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 5 Part (A) Engineering Pages: 493-508
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work presents an improving of the photovoltaic / thermal efficiency by using a solar tracking system (2-axes) and AL2O3 mixed with water as working fluid. An integrated system (PV/T) consists of 36 mono-crystalline solar cell was designed and implemented with cooling water technique utilized copper pipes on the back PV side to flow cooling water at different mass flow rates . A (90) bulbs of (12V, 50W) are connected in series are used to simulate the sun light and controled by (3) AC to AC transformers to give different irradiation arrive up to (1000 W/m2).The (AL2O3) was prepared and added to the water with different concentrations to decrease the temperature of PV and increase the rate of heat transfer to maintain good electrical efficiency and an increase in thermal efficiency.The experimental work has been conducted in (UMPEDAC) / Malaysia. The experimental results indicated that when using two- axes solar tracking system the output power generated was increased from (21.69W) to (30.69W). The power module generated is decreased when the temperature of PV surface increased from (64.05W at 24.7oC) to (39.46W at 79.1oC). It is proved that the temperature of PV surface is rising and that efficiency does not exceed 8%, if there is no water-cooling while under the influence of process cooling water, the efficiency increased to 9.6%. In addition, it founded that the optimum mass flow rat of water was (0.2) L/s. At using nanofluid (AL2O3-water) as a percentage ratios (0.1, 0.2, 0.3, 0.4, 0.5) % at constant mass flow rate (0.2) L/s, the temperature dropped significantly from (79.1oC) to (42.2oC). It is found that an optimum concentration ratio of nanofluid at 0.3% and the electrical efficiency of PV/T was 12.1% while the thermal efficiency was 34.4%.


Article
Study and Analysis of Concentric Shell and Double Tube Heat Exchanger Using - Al2O3 Nanofluid
الدراسات والتحاليل للمبادل الحراري ذو القشرة والانابيب المتداخلة المتمركزة باستخدام مائع نانوي كاما اوكسيد الالمنيوم

Authors: Noor Sabih Majeed نور صبيح مجيد --- Basma Abbas Abdulmajeed بسمة عباس عبد المجيد
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2017 Volume: 23 Issue: 9 Pages: 50-62
Publisher: Baghdad University جامعة بغداد

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Abstract

Heat exchanger is an important device in the industry for cooling or heating process. To increase the efficiency of heat exchanger, nanofluids are used to enhance the convective heat transfer relative to the base fluid. - Al2O3/water nanofluid is used as cold stream in the shell and double concentric tube heat exchanger counter current to the hot stream basis oil. These nanoparticles were of particle size of 40 nm and it was mixed with a base fluid (water) at volume concentrations of 0.002% and 0.004%. The results showed that each of Nusselt number and overall heat transfer coefficient increased as nanofluid concentrations increased. The pressure drop of nanofluid increased slightly than the base fluid because of the low concentration used.

للمبادل الحراري اهمية في الصناعة سواء في عملية التبريد او التسخين. لزيادة كفاءة المبادل الحراري استخدم المائع النانوي لتحسين انتقال الحرارة بالحمل بالمقارنة مع السائل الاعتيادي. تم استخدام السائل النانوي المتكون من كاما اوكسيد الالمنيوم مع ماء للتبريد في المبادل الحراري ذو الغلاف والانابيب المتداخلة والمتمركزة والذي يجري باتجاه عكسي مع تيارالزيت الساخن. هذه الدقائق النانوية ذات قطر 40 نانو متر, خلطت مع الماء بتراكيز حجمية 0.002 % مع 0.004 %. اظهرت النتائج ان عدد نسلت و معامل الانتقال الحراري الكلي قد ازداد بزيادة تركيز المادة النانوية. ان فرق الضغط للسائل النانوي قد ازداد زيادة طفيفة نتيجة استخدام تركيز واطئ.

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