Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2016
Öğrenci: EYLÜL ŞİMŞEK
Danışman: HANİFE TUBA OKUTUCU ÖZYURT
Özet:The present study investigates thermal and hydrodynamic performance of nanofluids in copper microchannels. Experiments are performed using spherical gold nanoparticles, and silver nanowires suspended in deionized (DI) water under constant heat flux condition. Polyvinylpyrrolidone (PVP) is used as the surfactant. In gold nanofluid experiments, effects of nanoparticle size (10, 50 and 100 nm), volumetric concentration (0.00064% - 0.0052%) and flow rate (100-140 μL/min) on the nanofluid performance are investigated in 70 μm×50 μm rectangular microchannels. In silver nanofluid experiments, microchannels of 200 μm×50 μm, 100 μm×50 μm and 70 μm×50 μm cross-sectional area are used. To investigate the surfactant effect, experiments are repeated with DI water, and a PVP – DI water solution. Among the investigated cases, the silver nanofluid showed the best thermal performance. Both silver and gold nanofluids yielded higher convective heat transfer coefficient than PVP – DI water solution, however the golf nanofluid occasionally showed better thermal performance compared to DI water. Nanofluid stability is also observed. This study contributes to the literature by considering the surfactant effect on stability, as well as thermal and hydrodynamic performance of nanofluids. Silver nanowires are experimented for the first time in the literature in microchannel heat sinks. Results indicated that surfactants may significantly lower the heat removal by nanofluids. A long term stability is achieved for both gold and silver nanofluids. The particle size and the flow rate are two very important parameters that affect thermal performance. The nanofluid with silver nanowires is proved to be promising in microchannel cooling applications.