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Article
STUDY OF MICROCHANNEL HEAT SINK PERFORMANCE WITH EXPANDED MICROCHANNELS AND NANOFLUIDS

Author: Mushtaq Ismael Hasan
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2016 Volume: 9 Issue: 4 Pages: 526-542
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In this paper a microchannel heat sink with expanded microchannels and nanofluids isnumerically investigated. The object of this paper is to study and improve the cooling performanceof microchannel heat sink. Both the geometrical parameters and working fluids were studied and acomparison was made between them. Expanded microchannels (sudden expanded and diverging)were used instead of straight microchannels, also micro pin fins with square and triangular shapeswere used for heat transfer enhancement. Sudden expanded microchannels were studied withdifferent expansion ratios and expansion lengths. Three types of nanofluids (Cu-water, Al2O3-waterand Diamond-water) with volume concentration (1 – 5) % were studied as working fluids and theireffects on overall performance of heat sink were compared with pure water. The results obtainedshows that the overall performance of microchannel heat sink increased with increasing theexpansion ratio or decreasing the expansion length. For the same expansion ratio the suddenexpanded microchannels gives higher modification compared with diverging microchannels. Alsousing of nanofluids lead to enhance the heat transfer and the improvement got by geometricparameters such as using of expanded microchannels or fins is much larger than that obtained byusing nanofluids for the same heat sink.


Article
Influence Of Wall Axial Heat Conduction On The Forced Convection Heat Transfer In Rectangular Channels
تأثير التوصيل الحراري المحوري ف الجذار على انتقال الحرارة بالحمل القسري خلال القنوات المستطيلة

Author: Mushtaq Ismael Hasan مشتاق اسماعيل حسن
Journal: Basrah Journal for Engineering Science مجلة البصرة للعلوم الهندسية ISSN: Print: 18146120; Online: 23118385 Year: 2011 Volume: 11 Issue: 1 Pages: 31-43
Publisher: Basrah University جامعة البصرة

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Abstract

In this paper the conjugate heat transfer in rectangular channel is numerically investigated, where the effect of both axial heat conduction and entrance region on the internal forced convection in rectangular channels are studied. With decreasing the dimensions of channels the thickness of walls become large and in order of the channels dimensions as in microchannels. As a results the heat conduction in the walls especially in the axial direction can not be ignored, since it lead to decrease in the efficiency of heat transfer process. Also the effect of entrance region is taken into consideration where the flow is assumed developing hydro dynamically and thermally. A finite volume method is used to numerically solve the conjugate heat transfer in both the fluid and wall simultaneously. The results obtained shows that the existing of axial heat conduction lead to reduction in the heat transfer and it's effect increased with increasing the thickness of walls and Reynolds number. In this paper a correlation has been developed to calculate the value of axial heat conduction in channel's walls based on most of the affecting parameters. This correlation can be used accurately to compute the value of axial conduction in rectangular channels


Article
Numerical Investigation of Hydrodynamic Characteristics of the Micro Irrigation Lateral
التحليل العددي للخصائص الهيدروديناميكية لمنظومات الري بالتنقيط

Author: Mushtaq Ismael Hasan مشتاق أسماعيل حسن
Journal: University of Thi-Qar Journal for Engineering Sciences مجلة جامعة ذي قار للعلوم الهندسية ISSN: 26645564/26645572 Year: 2010 Volume: 1 Issue: 1 Pages: 23-36
Publisher: Thi-Qar University جامعة ذي قار

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Abstract

In this paper , the analysis of the hydraulics of micro irrigation lateral is made and the effect of the design parameters (ground slope, length of lateral and velocity of flow) on thehydrodynamic performance of this lateral pipe is numerically studied. The numerical solution for this model is made using the finite difference method which considered accurate and simple compared with other analytical and numerical methods used in literature to study micro irrigation systems. The numerical model used in this paper is validated by comparing its results with results of another numerical methods presented in literature .The results obtained show that, the parametersstudied in this paper play an important role on the hydrodynamic performance of the micro irrigation systems.

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Article
NUMERICAL INVESTIGATION OF MICROCHANNEL HEAT SINK WITH MEPCM SUSPENSION WITH DIFFERENT TYPES OF PCM

Authors: Hind Lafta TBENA --- Mushtaq Ismael HASAN
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2018 Volume: 11 Issue: 1 Pages: 115-133
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

The aim of this paper is to study the microencapsulated phase change materials (MEPCM) suspension as a coolant instead of pure fluid in the micro channel heat sink (MCHS) with different core and wall materials as well as different base fluids. The MEPCM suspension using in this study consist of microcapsules constructed from n-octadecane, RT44 as a phase change materials (PCM) and shell materials are poly-methylmthacrylate (PMMA), poly-alpha olefin (PAO), these capsules are suspended in (pure water, ethylene glycol and pure oil) in a concentration of (0–20)% and have been used as a cooling mediums at different ambient temperatures. Constant heat flux is applied at base of heat sink. The results obtain show that, using MEPCM suspensions as a coolant in micro heat sink instead of conventional cooling with pure fluid lead to enhance the cooling performance of micro heat sink is be 20.91% with (RT44+PMMA) pure oil, 16.91% with (RT44+PMMA) for ethyleneglycol and 12.91% with (RT44+PMMA) for pure water at concentration 2% and


Article
EVALUATING THE INFLUENCE OF SOME DESIGN AND ENVIRONMENTAL PARAMETERS ON THE PERFORMANCE OF EARTH TO AIR HEAT EXCHANGER

Authors: Sajad Waleed Noori --- Mushtaq Ismael Hasan
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 2 (Part-1) Pages: 10-29
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The earth to air heat exchangers (EAHE) is effective passive cooling and heating techniques for buildings. This paper studies numerically the effect of some design and environmental parameters (moist content of soil, pipe material and thickness of pipe wall) on the overall performance of EAHE system. Three types of soil were selected (dry soil, moist soil and saturated soil) with two pipe materials PVC and steel and three thicknesses of pipe wall (2, 3 and 6 mm). This numerical study has been done for summer and winter seasons according to the weather conditions for Nasiriyah city in southern of Iraq. First the built numerical model was validated against experimental model and the results of comparison showed good agreement. After the validation the overall performance of EAHE system with selected parameters was analyzed with ranges of air velocity, inlet temperature and pipe length of 50 m. The simulated results showed that the very moist or saturated soil gives the best overall performance of EAHE system compare with other soils, Furthermore there is no significant effect of pipe material and wall thickness on the overall performance.


Article
Effect of variable fluid properties on the hydrodynamic and thermal characteristics of parallel flow microchannel heat exchanger
تأثير الخواص المتغيرة للمائع على الخصائص الهيدروديناميكيه والحراريه للمبادل الحراري المتوازي المايكروي

Author: Dr. Mushtaq Ismael Hasan م.د. مشتاق إسماعيل حسن
Journal: Univesity of Thi-Qar Journal مجلة جامعة ذي قار العلمية ISSN: 66291818 Year: 2015 Volume: 10 Issue: 4 Pages: 1-14
Publisher: Thi-Qar University جامعة ذي قار

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Abstract

In this paper the parallel flow microchannel heat exchanger is numerically investigate and the effect of treating the properties of fluids as variables with temperature compared with constant fluid properties assumption on its performance is studied. A numerical simulation is made to solve 3D Navier stock equations in two fluids with temperature dependent properties and 3D energy equation in two fluids and solid walls taking into account the effect of entrance region and axial conduction in the walls.The properties entered to the main program by relations as a function of temperature using subroutines written to calculate the properties at the end of each iteration. The results obtained show that, treating the properties as a temperature dependent gives higher overall performance since it leads to obtain lower pressure drop and higher effectiveness compared with constant properties assumption.

تم في هذا البحث دراسة تأثير خواص الموائع كقيم متغيرة على أداء المبادل الحراري المتوازي المايكروي مقارنة مع فرضية الخواص الثابتة. تم حل معادلات نافير ستوك ثلاثية الأبعاد عدديا في كلا المائعين مع خواص متغيره كذلك تم حل معادلة الطاقة ثلاثية الأبعاد عدديا في كلا المائعين والجدران الفاصلة بينهما والأخذ بنظر الاعتبار تاثير كل من منطقة الدخول والتوصيل الحراري المحوري في الجدران. تم إدخال خواص الموائع الى البرنامج الرئيسي على شكل علاقات بدلالة درجه الحرارة خلال برامج فرعية كتبت لحساب الخواص عند نهاية كل تكرار للبرنامج. النتائج التي تم التوصل اليها تشير الى ان فرضية معاملة الخواص كقيم متغيرة مع درجة الحرارة تعطي اكبر اداء للمبادل حيث انها تؤدي الى الحصول على هبوط ضغط اقل وفعالية أعلى للمبادل مقارنة مع فرضية الخواص الثابتة.


Article
ENHANCEMENT OF THERMAL PERFORMANCE OF DOUBLE PIPE HEAT EXCHANGER BY USING NANOFLUID

Authors: Mushtaq Ismael Hasan --- Mohammed Dakhel Salman --- Ayat Lateef Thajeel
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 2 (part-6) Pages: 150-165
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

In this paper, the performance of double pipe heat exchanger was studied experimentally with two flow arrangements (counter and parallel flow) and two types of nanofluid as a cooling fluid. A (20 nm) nanoparticles of (Al2O3 and TiO2) are used with deionized water as base fluid. The nanoparticles volume concentrations which studied were (0.05, 0.1, 0.15, 0.2, 0.3) % and flow rates were (0.5, 1, 1.5, 2) L/min for water and NF. Hot fluid (water) and cold fluid (Nanofluid) flow in heat exchanger with constant inlet temperature of 59.3 C° and 30.7 C° respectively, so the two fluids flowing with constant inlet velocity. The experimental results showed that the nanofluid absorbed heat more than the water at low flow rate, which would lead to improve the thermal performance of heat exchanger due to enhancing of thermo physical properties of these fluids. Also, it showed that the heat transfer rate increased with the increasing of nanoparticles concentration. In the same context, one notice the effect of the type of nanoparticles on the rate of heat transfer, where Al2O3-water NF had heat transfer rate greater than that for TiO2-water NF. In addition, it showed that the maximum heat transfer coefficient (HTC) at 0.3% volume concentration was enhanced by 18.25% and 15.5% for AL2O3-water nanofluid and TiO2-water nanofluid respectively with 20 nm diameter.


Article
Analysis of Solar Powered Air Conditioning Systems for Residential Applications
تحليل منظومات التكييف التي تعمل بالطاقة الشمسية للتطبيقات المنزلية

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Abstract

In this paper the absorption air conditioning system has been analyzed, and the solar energy has been used as a source for heat required to operating the absorption cycle. The influence of most of the parameters which may affect the performance of absorption air conditioning system has been studied under the climatic conditions of Iraq. The mainadvantage of solar based air conditioning systems is the synchronization between the cooling demand and the availability of solar energy especially in hot regions like Iraq which containshuge potential of solar energy in summer season. The results obtained indicate the ability of using solar energy to reduce the electricity consumption for air conditioning applications. For a certain space with cooling load 5 Ton (17.5 kW) for climatic conditions (solar radiationintensity 1000 W/m2 and ambient temperature 45 oC) the solar collector with area 40 m2 can provide 75% of required heat to produce this cooling load demand and a collector with area 53 m2 can provide 100 % of required heat to produce this cooling load demand for theseclimatic conditions.

في هذا البحث تم دراسة وتحليل منظومة تكييف الهواء الامتصاصية وتم استخدام الطاقة الشمسية كمصدر للحرارة اللازمة لتشغيل هذه الدورة الامتصاصية. تم دراسة تأثير معظم العوامل التي من الممكن أن توثر على أداء منظومة تكييف الهواء الامتصاصية بالظروف المناخية للعراق. الميزة الأساسية لمنظومات التكييف التي تعمل بالطاقة الشمسية هي التوافق بين الطلب على التبريد وتوفر الطاقة الشمسية خاصة في المناطق الحارة مثل العراق والتي تحتوي على إمكانيات هائلة للطاقة الشمسية خاصة في فصل الصيف.

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