Effect of Particle Type on Cyclone Formation Inside a Solar Reactor

Min-Hsiu Chien,Gerald Morrison,Nesrin Ozalp

doi:10.3389/fmech.2016.00006

Min-Hsiu Chien, Gerald Morrison + Show 1 more

Open Access

https://doi.org/10.3389/fmech.2016.00006

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Abstract

Solar reactors featuring a circulating cyclone flow pattern provide enhanced heat transfer and longer residence time increasing conversion efficiency. Cyclone flow also works in reducing particle deposition on solar reactor walls and exit which is particularly important issue in solar cracking reactors to avoid clogging. This paper focuses on the physics of cyclone formation inside a solar cracking reactor and experimentally analyzes the effect of particle entrainment on the flow pattern via two dimensional Particle Image Velocimetry (PIV). The cyclone flow structure in the reactor is reconstructed by capturing images from orientations perpendicular or parallel to the geometrical axis of the reactor. In order to conduct PIV measurements and to reconstruct the cyclone structure inside the solar reactor, the experiment was operated at room temperature with the flow configuration matching that of a solar reactor operating at high temperatures. Two types of seeding particles were tested, namely tri-ethylene glycol (TEG) and solid carbon. The effectiveness of the screening flow was evaluated by measuring the quantity of solid particles deposit on the reactor walls. The Stokes flow analysis of each particle species was performed and the cyclone vector fields generated by using different particles are compared.

Highlights

Hydrogen and carbon black production from solar cracking process is an emission-free alternative to industrially practiced methods that are being used to produce these important commodities
The carbon particles, which are a product of the decomposition reaction, affect the efficiency of the solar reactor in the form of interaction of radiation between the carbon particles and the fluid
Cyclone flow formation is considered as a promising solution to reduce carbon deposition inside the reactor (Shilapuram et al, 2011; Devanuri and Ozalp, 2013)

Summary

Introduction

Hydrogen and carbon black production from solar cracking process is an emission-free alternative to industrially practiced methods that are being used to produce these important commodities. The carbon particles, which are a product of the decomposition reaction, affect the efficiency of the solar reactor in the form of interaction of radiation between the carbon particles and the fluid. A higher carbon particle concentration leads to a larger optical thickness, and a higher attenuation of radiation occurs. A large optical thickness is beneficial in absorbing the solar energy and reducing the temperatures of both reactant and the reactor wall. Cyclone flow formation is considered as a promising solution to reduce carbon deposition inside the reactor (Shilapuram et al, 2011; Devanuri and Ozalp, 2013). Concept of cyclone or tornado flow inside a solar reactor to reduce carbon deposition was originally introduced by Kogan and Kogan (2002)

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