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- In relation to this article, we declare that there is no conflict of interest.
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Received January 3, 2025
Revised January 22, 2025
Accepted February 3, 2025
Available online February 1, 2025
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This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits
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태양열 유동층 입자흡열기를 위한 탄소나노튜브 마이크로비드의 성형
Fabrication of Carbon Nanotube Microbeads for Solar Fluidized Bed Particle Receiver
https://doi.org/10.9713/kcer.2025.63.2.105114
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Abstract
유동층 적용이 어려운 탄소나노튜브 분말을 태양광 유동층 흡열기에 적용가능하기 위한 마이크로 비드 제조법이 제안되었다. 이 방법은 m-cresol을 분산제로 이용하고, 마이크로 수준의 입자 성형을 위한 교반기에 의한 분쇄 및 1차 응집제 표면의 잔류 m-cresol을 세척하여 재응집을 방지하는 것을 특징으로 하였다. 다양한 방법 중, 입자 표 면 물과 흡유지를 이용한 표면 분산제 제거를 통해 성형된 입자는 평균 입도 363 m이고, 겉보기 입자밀도는 251 kg/m3 으로 유동성이 좋은 Geldart A 입자로 분류되었다. 제작된 입자는 높은 열용량(1,039 J/kg·K) 과 태양광 에너지 흡 수율(98.78%)을 나타내어, 입자 흡열기에 적용 가능성을 나타내었다. 입자 유동 특성에 있어 자유흐름 그룹에 해당 하는 낮은 안식각(33.8°)을 보였다. 유동층 흡열기 냉간장치(50 mm I.D. × 1000 mm high)를 이용한 유동화 실험에서 CNT 분말 및 기존 성형법에 의한 마이크로 비드 대비, 낮은 최소유동화 속도(0.056 m/s) 를 나타내어, 유동층 흡 열기에 적합함을 보였다.
Recent interest in solar fluidized bed receivers (SFBR) for preheating gases at medium to low temperatures has been growing attention toward enhancing their energy efficiency by utilizing carbon nanotubes (CNTs) as particle materials. To enable the application of CNT powders, which are challenging to fluidize, in the SFBR, a microbead fabrication method has been proposed. The method involves the use of m-cresol as a dispersant, mechanical agitation for micro-scale beads formation, and removing the residual m-cresol on the surface of primary agglomerates to prevent re-agglomeration. Among various techniques, microbeads formed by removing surface dispersants using water and cresol-absorption exhibited an average particle size of 363 μm and an apparent density of 251 kg/m3, classifying them as Geldart A particles with excellent fluidization properties. The fabricated microbeads demonstrated high thermal capacity (1,039 J/kg·K) and solar energy absorption efficiency (98.78%), indicating their suitability for SFBRs. The microbeads showed a low angle of repose (33.8°), corresponding to a free-flowing group. Fluidization experiments conducted using a cold-flow fluidized bed model (50 mm I.D. × 1000 mm height) revealed a lower minimum fluidization velocity (0.056 m/s) compared to CNT powders and conventionally fabricated microbeads fabricated, confirming their applicability to SFBRs.
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