Non-reacting cfd analysis of a drop tube furnace used for solid fuel combustion

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: GAMZE GÜLENÇ

Danışman: FEYZA KAZANÇ ÖZERİNÇ

Özet:

In this thesis, the flow inside the drop tube furnace (DTF) which was already built in the Clean Combustion Technologies Laboratory located in Department of Mechanical Engineering at Middle East Technical University is analysed by using Computational Fluid Dynamics method. DTF is a semi-pilot scale electrically heated reactor with the aim of achieving constant temperature zone to investigate combustion characteristics of solid fuels. A simplified geometry is created for the flow analysis inside the DTF. The heating zone of the reactor is heated up to 1273 K and total air volumetric rate entering the inlets of the furnace is 10 L/min for the analyses conducted in the thesis. Natural convection governs the flow inside the furnace. Three different turbulence models (Standard k-ε, Realizable k-ε and SST k-ω) are employed in order to obtain velocity magnitudes and temperature distribution in the DTF. Transient solution is used for the simulation in which SST k-ω model is utilized to achieve convergence. The results are compared to analysis results in literature and temperature measurements performed. The analyses using k-ε models provide more similar trends with analysis results in literature and measurements. Constant temperature zone is achieved with k-ε models. Furthermore, gravitational effect is investigated. In the analysis where gravitational effect is neglected, the air continues to flow through the whole reactor with the declining velocity from 0.3 m/s to 0.1 m/s. However, in reality, the flow is stagnant at the exit of the heating zone, and the flow is maintained using a vacuum pump.