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Article
USING TIO2 NANOFLUID FOR ENHANCING PERFORMANCE OF A WATER CHILLER
أستخدام أوكسيد التيتاينوم لتحسين أداء منظومة تثليج الماء

Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2015 Volume: 19 Issue: 5 Pages: 16-27
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

In the present work an experimental study is carried out to enhance performance of water chiller system by using nanofluid (water+TiO2 ) in shell side of chiller with different volume concentration (0.05% , 0.075% and 0.1%) . Experimental work includes two parts; In the first one COP of the system is calculated by using two alternative refrigerants (R-407c and R-134a). In the second part, the optimum COP is fonnd using various concentration of TiO2 nanofluid for system with alternative refrigerant. Experimental results show that the COP of R-134a is better than R407c which will be used in the second part of the present study with nanofluid in shell side of the system. The COP with (0.1%) nanofluid has been found to increase by (8.5%).

تم في هذا البحث دراسة عملية لتحسين اداء منظومة تثليج الماء باستخدام مائع نانوي (ماء+اوكسيد التيتانيوم( خالل غالف القشرة لمبادل حراري)المبخر( وبتراكيز مختلفة (%1.0 and 075.0,05.0 .)وتضمن البحث جزئين: في الجزء االول تم حساب معامل االداء باستخدام موائع بديلة R134aوR407c . وفي الجزء الثاني تم استخدام المائع النانوي في المبخرلتحسين معامل اداء المنظومة .وقد اوضحت النتائج العملية ان معامل االداء للمنظومة عند استخدام R134a افضل من R407c , لذلك استخدم في الجزء الثاني اي مع وجود المائع النانوي, وكذلك اتضح ان معامل االداء باستخدام (%1.0 (من المائع النانوي ازداد بنسبة )%5.8.


Article
Performance Evaluation of the V–basin Tube Solar Collector by Using .Different Nanoparticles and Base Fluids

Authors: Ibtisam A. Hasan --- Khaliid F. Sultan
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 4 Part (A) Engineering Pages: 461-470
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This research discuss the performance and evaluation of V –basin collector in heating systems of solar with different nanofluids and base fluids, where metal nanofluids [Ag (20nm) + DW + EG], and metal oxide nanofluid [TiO2 (40nm) + DW + EG]are the used operating fluids with flow rate of 25 lit/hr, 50 lit/hr and ratios of concentration (i.e. 1, 2, 3 and 5 % vol). The base fluids employed in these experiment is distilled water and ethylene glycol. The metal and oxide metal nanofluids are shown a significant improvement in the performance of V –basin tube solar collector with higher thermal conductivity as well as heat transfer comparing to the base fluid (distilled water and ethylene glycol). The metal nanofluids [Ag (20nm) + DW + EG]at 5 % vol and flow rate of 25, and 50 lit/hr showed an important impact in characteristics values of thermal solar for fR(τα),–fRULwere.–6.317 W/m2. 0K, 0.522 and.–6.524 W/m20K, .0.542, whereas for the oxide nanofluid (TiO2 (40nm) + DW+EG) were –5.523 W/m20K, 0.473 and –5.1731 W/m2. 0K, 0.502 severally. The characteristics values of thermal solar to Dw and EG for flow rate of 25 lit/hr and 50 lit/hr were – 4.033 W/m2.0K, 0.382, –4.065 W/ m2.0K, and 0.421 severally. The size and type of nanofluid are necessary to enhancement heat transfer process, and improve performance of solar collector of V-basin type. The metal and oxide nanofluids used as a working fluid may improve the thermal performance of tube solar collector of V – basin because of small nanoparticles for metal, oxide metal and high thermal conductivity of silver. The metal and oxide nanofluids achieved an improvement when it was compared to DW and EGmostly at a high. Inlet temperature. The impacts of metal .nanofluid and oxide metal nanofuids are taken into regard on solar nanofluids system of heating as well as different base fluids.


Article
NUMERICALSTUDY OF MIXED CONVECTION FLOWIN ALID

Author: Huda A. Al-Mayahi
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2018 Volume: 9 Issue: 3 Pages: 128-144
Publisher: University of Kufa جامعة الكوفة

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Abstract

A numerical investigation of steady laminar mixed convection flow of a Copper-water nanofluid in a lid –driven cavity has been executed. In the present study, the left vertical and inclined walls are heated at constant temperature while the right vertical and inclined right walls are maintained at constant cold temperature. The bottom wall is adiabatic and moving with uniform velocity. The study has been carried out for Rayleigh number Ra= 104– 106, Reynolds number Re=20-100 and solid volume fraction of Cu nanoparticles Ø= 0-0.05. The effective viscosity and thermal conductivity of the nanofluid have been calculated by Brinkman and Maxwell-Garnett models, respectively. The results indicated that, the Nusselt number increases with increasing Ra, Re and Ø.


Article
THERMAL STABILITY ANALYSIS OF LAMINAR NANOFLUIDS FREE CONVECTION IN HORIZONTAL CYLINDER

Author: Imad Shukri. Windi
Journal: Iraqi journal of mechanical and material engineering المجلة العراقية للهندسة الميكانيكية وهندسة المواد ISSN: 20761819 Year: 2014 Volume: 14 Issue: 3 Pages: 367-378
Publisher: Babylon University جامعة بابل

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Abstract

The effect of nanoparticles on the heat transfer of the fluids becomes one of the most interesting fields for researches. Metallic and nonmetallic materials are used to enhance the thermal performance of the fluids. In this work, an attempt was made to extend the work in this field to study the effect of addition of copper oxide nanoparticles on the transient behavior of free convection in horizontal cylinder. The dimensionless form of the energy and the momentum equations was solved using the commercial package COMSOL 3.5. A constant wall temperature CWT boundary condition was subjected to the surfaces of the cylinder. The lower half of the walls temperature was always higher than the upper one. The effect of volume fraction of nanoparticles on the stability of the transient behavior of the heat transfer and the fluid flow was examined. Also the effect of Rayleigh number on the velocities, temperature and Nusselt number are shown graphically. It is found that not only the onset of instability of the natural convection but also the type of the steady state profiles of temperature and velocities were affected by the existence of the nanoparticles. A phase plane plot was used to analysis the steady state types of dynamic behavior of the nanofluid natural convection under the CWT boundary condition.

تأثير الجسيمات النانوية على انتقال الحرارة خلال السوائل يصبح واحدا من المجالات الأكثر إثارة لاهتمام الباحثين . وتستخدم المواد الفلزية واللافلزية لتعزيز الأداء الحراري للسوائل . في هذا العمل ، كانت هناك محاولة لتوسيع العمل في هذا المجال لدراسة تأثير إضافة أكسيد النحاس على السلوك الغيرمستقر للحمل الحراري الحر في اسطوانة أفقية . تم حل نموذج غيربعدي لمعادلات الطاقة و الزخم باستخدام برنامج COMSOL 3.5. وقد تم اختيار حدود المعادلات في حالة تعرض الاسطوانة الى درجة حرارة الجدار ثابت CWT. وكان النصف السفلي من جدران الاسطوانة دائما بدرجة حرارة أعلى من العلوي . تم فحص تأثير النسب الحجمية من الجسيمات النانوية على ثبات سلوك استقرار لنقل الحرارة و تدفق السوائل . أيضا وتظهر تأثير عدد رايلي على السرعات ، ودرجة الحرارة وعلى عدد نسلت بيانيا . وقد وجدت أنه ليس فقط بداية حدوث عدم الاستقرار للحمل الحراري الطبيعي ولكن أيضا نوع منجني الحالة المستقرة لدرجة الحرارة و السرعات تأثرت بوجود الجسيمات النانوية . تم استخدام مخططات مستوي المرحلة لايجاد تحليل أنواع حالة الاستقرار للسلوك الديناميكي للموائع النانوية للحمل الحراري الطبيعي تحت شرط الحدود CWT .

Keywords

stability --- natural convection --- nanofluid --- CuO --- COMSOL


Article
NUMERICAL SIMULATION OF NATURAL CONVECTION IN AN OBLIQUE ENCLOSURE FILLED WITH SILVER –WATER NANOFLUID
النمذجة العددية للحمل الحر في حيز مائل مملوء بمائع الفضة النانوي

Author: Farooq Hassan Ali فاروق حسن علي
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2016 Volume: 9 Issue: 1 Pages: 87-105
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In this work, a numerical simulation of natural convection in an oblique enclosure filled with silver-water nanofluid is obtained for different values of Rayleigh numbers, volume fraction and inclination angle of sloping walls. The considered oblique enclosure with left and right side walls are maintained at constant cold temperature (Tc). The horizontal top wall of enclosure is kept insulated, but the bottom is maintained at constant hot temperature (Th). The present work is utilized to obtain results in the range of Rayleigh number (103-106) , volume fraction of nanofluid varied from (0-0.2) and inclination angle of side walls are (-60o, -30o, 0o, 30o, 60o). The Prandtle number is 6.0. The governing equations in the two-dimensional are solved numerically by using finite-difference technique. Comparisons with other works are performed and the results are found to be in good agreement. The obtained results are shown in the form of stream function, isothermal lines and average Nusselt numbers. It observed from results that acute shaping wall and Ag-nanoparticles with high concentration are effective to enhance the rate of heat transfer, also; the average Nusselt number for all range of inclination angle increases with increase in the Rayleigh number and the solid volume fraction of the Nanofluid.

تمت دراسة الحمل الحر في حيز مائل يحتوي على مائع الفضة النانوي لقيم مختلفة من ارقام رالي، الحجم الجزئي، زاوية ميلان الجدار. اعتبرت الجدران الجانبية المائلة الايمن والايسر للحيز عند درجة حرارة باردة. الجدار الافقي الاعلى اعتبر معزولا، بينما كان الجدار الافقي الاسفل عند درجة حرارة ساخنة. كان رقم رالي يتراوح بين((106-103، بينما تراوح الحجم الجزئي بين ((0.2-0 وتراوحت زاوية ميلان الجدران الجانبية بين ((60o, 30o, 0o, -30o, -60o. وكان رقم برانتل يساوي .6.0 تم حل المعادلات الحاكمة لبعدين عدديا باستخدام تقنية الفروقات المحددة.جرت المقارنة مع بحوث سابقة واظهرت النتائج تطابق جيد. مثلت نتائج هذه الظاهرة بدالة الجريان، خطوط الحرارة وارقام نسلت. لقد لوحظ من النتائج ان للزوايا الحادة للجدار واضافة مائع النانوي بتراكيز عالية الاثر الكبير في تعزيز انتقال الحرارة، كذلك ان متوسط رقم نسلت لجميع زوايا الميلان يزداد بزيادة رقم رالي وكذلك زيادة تركيز المائع النانوي.


Article
Natural Convection Heat Transfer in Arc Shape Wall Porous Cavity Filled with Nano-Fluid

Authors: Muneer A. Ismael --- Huda A. AL-Mayahi --- Ihsan N. Jawad
Journal: Basrah Journal for Engineering Science مجلة البصرة للعلوم الهندسية ISSN: Print: 18146120; Online: 23118385 Year: 2014 Volume: 14 Issue: 2 Pages: 137-148
Publisher: Basrah University جامعة البصرة

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Abstract

Natural convection heat transfer in porous cavity with arc shape wall filled with nanofluid is studied numerically. The right arc shape wall of the cavity is heated at constant temperature (Th) while the left wall is kept cold at constant temperature (Tc), and the other horizontal walls are thermally insulated. The governing equations of the heat transfer and nanofluid flow are solved Flex PDE software. A temperature independent nanofluids properties models are adopted. The investigated parameters are the nanoparticles volume fraction Ø= (0-0.2), Rayleigh number Ra (10-1000) and arc center Ce (1-∞). The results are presented by contour of streamlines, isotherms and the average Nusselt number. The results have showed that the average Nusselt number decreases with increasing Ce and increases with increasing Ra and Ø.


Article
Experimental Comparison Between Conventional Coolants and (TiO2/Water) Nano fluid to select the best Coolant for Automobiles in Iraq's Summer Season

Author: Abdulmunem R. Abdulmunem
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 5 Part (A) Engineering Pages: 912-926
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work, presentsnanofluids as a new coolant technology in automobile engines compared with other conventional coolants (Ethylene glycol/water(antifreeze), distilled water) experimentally.The increase in thermal conductivity of the base fluid (water) by adding nanoparticles in certain ratios led to more absorption of heat from engine block. The experimental results indicated that the drooping in exit engine coolant temperatures was about(18.5%) by using (0.3%TiO2/water)nanofluid, and about (9%) by using distilled water comparative with Ethylene glycol/water(50/50) at the test end. The increasing in radiator(heat exchanger) effectiveness was about (51%) with using nanofluid, and about (29%) with using distilled water comparative with Ethylene glycol/water(50/50) at the test end. The results indicated also that the increasing in Nusselt’s number at entrance of radiator hose was about (42.8%) with usingnanofluid and about (30.5%) with using distilled water compared with Ethylene glycol/water(50/50).This led to increase convection heat transfer coefficient at entrance of radiator hoseby about (65%) with using nanofluidand about (49.5%) with using distilled water compared with Ethylene glycol/water (50/50).


Article
Theoretical Temperature Distribution Investigation in Electrical Transformer by Using Nano-Technology

Authors: Ibtisam A. Ha san --- Sahar R. Fafraj --- Azhar K. Azeez
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 12 Part (A) Engineering Pages: 2282-2295
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

A proposed thermal model is examined for a distribution transformer. A 2d simulation by a transient analysis in light of the Finite Element Method (FEM) was done to obtain the temperature distribution in the three phase transformer (250 KVA 11/.416 KV core type, mineral oil) using "ANSYS PROGRAM". Meanwhile, the effects of type of oil on HOST are investigated using the proposed model. To test the effect of nanoparticles on heat transfer process, the insulation oil was changed with Nanofluid; it has been used two types of Nano particles (CuO and Al2O3) with 0.5% as a volume concentration, where themaximum temperature reduced about (5%).The core material also has been changed from silicon steel to amorphous steel and caused a reduction in maximum temperature about (9.9%) in HV winding and change the interior angles from 90o to 135o, where the temperature distribution transformer is improved. The present model successfully accomplished for expecting the temperature distribution at any locations in the transformer when compared with practical measurement.


Article
EXPERIMENTAL AND NUMERICAL STUDY OF ENHANCEMENT HEAT TRANSFER COEFFICIENT IN SPIRAL FLUTED TUBE HEAT EXCHANGER WITH NANOFLUID
دراسة عملية و عددية لتحسين أنتقال الحرارة في انبوب لولبي مخدد بوجود المائع النانوي

Authors: Muna S. Kassim --- Fouad A. Salah --- Ahmed O.Samarmad
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2015 Volume: 19 Issue: 6 Pages: 165-183
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Experimental and numerical investigation has been performed in this work to study enhancement of heat transfer coefficient in spiral fluted tube heat exchanger with Nanofluid. The shell side was made from galvanized tube of (65 mm) outer diameter. The tube was made from copper material of (1000 mm) length having (16 mm) equivalent inner diameter and (17 mm) outer diameter, it was inserted inside the shell. Steam was used, as a heating source where constant wall temperature condition (110˚C) was achieved, and TiO2 /water nanofluid with various volume concentrations (0.08%, 0.1%, 0.2%, and 0.3%) by volume at Reynolds numbers (7000 to 15000) has been employed, as working fluid flows through the inner tube. Fiber glass has been utilized to cover the outer surface of the shell for reducing heat losses. The performance of spiral fluted tube heat exchanger with and without nanofluid was investigated experimentally. Experimental results reveal that the use of spiral fluted tube without nanofluid leads to increase (28-33) % in heat transfer coefficient compared with smooth tube, and the maximum increase in heat transfer coefficient occurs when using spiral fluted tube with nanofluid at 0.3% volume concentration was about (25-28) % higher than the pure water in spiral fluted tube. Empirical correlations for water, nanofluid were represented by Nusselt number. Numerical simulation has been carried out on present heat exchanger to analyze both flow field and heat transfer using ANSYS 14, FLUENT package. The comparison between experimental and numerical results showed good agreement.

في هذا العمل تم انجاز دراسة عملية وعددية لتحسين انتقال الحرارة باستخدام انبوب لولبي مخدد بوجود المائع النانوي. القشرة مصنوعةمن الحديد المغلون 65 مليمتر قطر خارجي. الانبوب مصنوع من النحاس بطول 1000 مليمتر ، 16 مليمتر قطر داخلي مكافئ و 17 مليمتر قطرخارجي تم تثبيته داخل القشرة. استخدم البخار كمصدر حراري على السطح الخارجي للانبوب حيث تم الحصول على درجة حرارة ثابتة لسطحالانبوب ) °C110 (، المائع النانوي من نوع اوكسيد التيتانيوم /ماء مقطر بتراكيز حجمية مختلفة ) 0.08 ، 0.1 ، 0.2 ، 0.3 (% و يمر داخلالانبوب عند عدد رينولدز يتراوح بين ) 7000 - 15000 (. تم عزل القشرة من الخارج بعازل حراري لتقليل الحرارة المفقودة.تمت دراسة اداءالمبادل الحراري ذو الانبوب اللولبي المخدد بدون ومع المائع النانوي. بينت النتائج العملية زيادة في معامل انتقال الحرارة بمقدار) 28 - 33 (% عنداستخدام الانبوب اللولبي المخدد بدون المائع النانوي مقارنه بالانبوب الاملس،تم الحصول على اقصى زيادة في معامل انتقال الحرارة عند استخدامالانبوب اللولبي المخدد بوجود المائع النانوي وبتركيز 0.3 % بمقدار ) 25 - 28 (%مقارنه باستخدام الماء في الانبوب اللولبي المخدد.تم ايجادعلاقات تجريبية للماء و المائع النانوي بدلالة رقم نيسلت.تم انجاز محاكاة عددية للمبادل الحراري لتحليل جريان المائع و انتقال الحرارة باستخدامالبرنامج المختص .ANSYS 14, FLUENT package هناك تطابق مقبول عند المقارنة بين النتائج العملية والعددية


Article
Experimental Analysis of Heat Transfer Enhancement and Flow with Cu,TiO2 Ethylene glycol Distilled Water Nanofluid in Spiral Coil Heat

Author: Khalid Faisal Sultan
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2017 Volume: 24 Issue: 3 Pages: 63-77
Publisher: Tikrit University جامعة تكريت

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Abstract

This experimental investigation was performed to improve heat transfer in the heat exchanger (tube of shell and helically coiled (using nanoparticles for turbulent parallel flow and counter flow of distilled water (Dw) and ethylene glycol (EG) fluids. Six types of nanofluids have been used namely: copper – distilled water, copper – distilled water and ethylene glycol, copper – ethylene glycol, titanium oxide – distilled water, titanium oxide – distilled water and ethylene glycol, titanium oxide – ethylene glycol with 0.5%,1%,2%,3% and 5% volume concentration as well as the range of Reynolds number are 4000 – 15000. The experimental results revel that an increase in coefficient of heat transfer of 50.2 % to Cu – Dw, 41.5% to Cu – ( EG + Dw ), 32.12 % for Cu – EG , 36.5% for TiO2 – Dw, 30.2 % to TiO2 – ( EG + Dw) and 25.5%, to TiO2 – EG . The strong nanoconvection currents and good mixing caused by the presence of Cu and TiO2 nanoparticles. The metal nanofluids give more improvement than oxide nanofluids. The shear stress of nanofluids increases with concentration of nanoparticles in case parallel and counter flow. The effect of flow direction insignificant on coefficient of overall heat transfer and the nanofluids behaves as the Newtonian fluid for 0.5%,1%,2%,3% and 5%. Good assent between the practical data and analytical prediction to nanofluids friction factor which means the nanofluid endure pump power no penalty. This study reveal that the thermal performance from nanofluid Cu – Dw is higher than Cu – (EG + Dw) and Cu – EG due to higher thermal conductivity for the copper and distilled water compared with ethylene glycol.

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