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العنوان
Preparation of Nanofluid system (NFs) for Heat Exchanger /
المؤلف
Mahmoud, Mohamed Abd-Elaziz.
هيئة الاعداد
باحث / Mohamed Abd-Elaziz Mahmoud
مشرف / Saad El-Sayed Mohamed Hassan
مشرف / Ahmed Mohamed Al-Sabagh
مناقش / Rania El-Sayed Morsi
تاريخ النشر
2019.
عدد الصفحات
117p.:
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
Analytical Chemistry
تاريخ الإجازة
1/1/2019
مكان الإجازة
جامعة عين شمس - كلية العلوم - الكمياء
الفهرس
Only 14 pages are availabe for public view

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from 117

Abstract

The thesis content can be portrayed briefly as three chapters:
 Chapter (I): General introduction:
- This chapter contains general introduction regarding the work done and includes two parts:
 Part (I): It contains an overview about definition of nanofluids and factors affecting on it, in addition to literature survey about nanofluids preparation and properties.
 Part (II): It illustrates the chemical structure of Titanium dioxide (TiO2) and Tungsten oxide (WO3), and its applications.
 Chapter (II): Preparation and characterization of rutile titania nanofluids stabilized in different surfactants base fluids:
In this chapter, a series of TiO2 nanofluids were prepared in the concentrations of 0.0625, 0.125, 0.25, 0.5, and 1 wt% using both CTAB and SDS surfactants as stabilizer. Several characterization techniques were utilized to characterize the prepared nano fluids and to measure the stability and sedimentation rate of the prepared nano fluids with and without surfactant. The used equipment’s are such as High Resolution Transmission Electron Microscope (HRTEM), Dynamic Light Scattering (DLS), Differential Scanning Calorimetry (DSC), PVS TM Rheometer. Zeta potential of TiO2/SDS system was found to be 45.2 mV, for TiO2/CTAB system was 39.6 mV and in case of TiO2/H2O system the Zeta potential was -27.8 mV. Capture photo for all titania concentrations showed that the TiO2/SDS nanofluids were stable after the 31 days and the particle size remained constant
Summary
xiv
for at least 10 days. This may be due to the ability of SDS to undergo ionization and increasing dispersion and entropy. With three different concentrations of TiO2/CTAB nanofluids containing high titania concentrations nanofluids (1%, 0.5% and 0.25%), the particle size remained constant for 10 days. However; the particle size considerably varied with time for the other two concentrations (0.125% and 0.0625%) nanofluids due to high ratio of surfactant to titania nanoparticles. Addition of nanoparticles to CTAB base fluid enhanced the thermal conductivity with a magnificent value. The maximum value reached 640 mS/cm for 0.5%TiO2/CTAB nanofluid at temperatures below 50 °C. This is attributed to self-organization of CTAB to form the potential hydrogen bonding centers in water. In addition, CTAB base nanofluids showed low viscosity values and low specific heat in comparison with SDS base fluids which are needed in the cooling industry.
 Chapter (III): Using an ionic surfactant to prepare stable tungsten oxide nanofluids through reducing the particle size distribution:
In this chapter, a series of tungsten oxide nanofluids was synthesized in the concentrations of 0.0625, 0.25 and 1 wt% using both CTAB and SDS surfactants of 1% as stabilizing agent. Multiple techniques used to characterize nanofluids, study the stability, study sedimentation rate and physical property for prepared nanofluids. The characterization techniques used are High Resolution Transmission Electron Microscope (HRTEM), Dynamic Light Scattering (DLS), Differential Scanning Calorimetry (DSC), PVS TM Rheometer. TEM showed a good dispersion of nano particles in the surfactant
Summary
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basefluids. Zeta potential of WO3/SDS, WO3/CTAB and WO3/H2O, systems was found to be -60.5 mV, 42.2 mV and -44.3 mV respectively. Capture photo for all WO3 concentrations showed that the WO3/CTAB nanofluids were stable within the 21 days, while the WO3/SDS nanofluids showed valuable stability over an extended period of time, due to the ability of SDS to undergo ionization which increases both the dispersion and entropy of the solutions. The maximum value of thermal conductivity reached 433mS/cm and 424 mS/cm for 1%WO3/CTAB and 1%WO3/SDS nanofluids at temperature of 60 °C.