실리콘 카바이드 입자(평균 입도 123 μm)의 유동층 태양열 흡열기의 성능 및 효율에 영향을 미치는 입자 거동 해석 을 위해 MP-PIC 모델을 이용하여 전산모사를 수행하였고, 기존 실험결과와의 비교를 통해 검증하였다. 특히, 본 연구에서는 실험적으로 접근하기 어려운 유동층 표면 부근에서의 거동을 모사함으로써 흡열 성능과 입자 거동과의 상호 영향을 분석하였다. CPFD 모사결과는 입자층 및 프리보드에서의 평균 고체체류량과 압력요동 등 수력학적 특성 실험 결과를 잘 예측하였다. 입자 흡열기에서 1차적으로 태양열 에너지를 흡수하여 층 내부로 전달하는 층 표면 부근에서의 국부 고체체류량은 입자층 내 기포거동에 따라 중심부에서 상대적으로 낮은 값을 나타내는 불균일 분포를 나타내 었다. 프리보드 영역에서 국부 고체체류량은 기체속도가 증가할수록 축방향과 각 높이에서의 횡방향에서 불균일성이 증가하였고, 이는 입자 흡열기의 프리보드 영역 내 비산된 입자에 의해 반사된 태양광 에너지 손실과 연관된 압력강하 상대표준편차 증가의 원인임을 나타내었다. 입자 흡열기 내 기체속도 증가에 따른 국부적인 기체 및 입자 속도의 변화에 대한 고찰을 통해, 유동층 내 국부적인 입자거동 특성은 Geldart B 입자 물성과 관련된 입자층 내 기포 거동과 밀접하게 연관됨을 확인하였다. 유동층 입자 흡열기의 성능 척도인 일사량 당 유동기체의 출입구 온도차(ΔT/IDNI)는 입자 층 표면 및 표면 상부 프리보드 영역 내 압력요동 RSD와 상관관계가 매우 높음을 확인하였고, 이 결과는 흡열기 성능 개선에 활용할 수 있을 것으로 판단되었다.

A CPFD (Computational particle fluid dynamics) model of solar fluidized bed receiver of silicon carbide (SiC: average dp=123 μm) particles was established, and the model was verified by comparing the simulation and experimental results to analyze the effect of particle behavior on the performance of the receiver. The relationship between the heat-absorbing performance and the particles behavior in the receiver was analyzed by simulating their behavior near bed surface, which is difficult to access experimentally. The CPFD simulation results showed good agreement with the experimental values on the solids holdup and its standard deviation under experimental condition in bed and freeboard regions. The local solid holdups near the bed surface, where particles primarily absorb solar heat energy and transfer it to the inside of the bed, showed a non-uniform distribution with a relatively low value at the center related with the bubble behavior in the bed. The local solid holdup increased the axial and radial non-uniformity in the freeboard region with the gas velocity, which explains well that the increase in the RSD (Relative standard deviation) of pressure drop across the freeboard region is responsible for the loss of solar energy reflected by the entrained particles in the particle receiver. The simulation results of local gas and particle velocities with gas velocity confirmed that the local particle behavior in the fluidized bed are closely related to the bubble behavior characterized by the properties of the Geldart B particles. The temperature difference of the fluidizing gas passing through the receiver per irradiance (ΔT/ IDNI) was highly correlated with the RSD of the pressure drop across the bed surface and the freeboard regions. The CPFD simulation results can be used to improve the performance of the particle receiver through local particle behavior analysis.

Solar particle receiver Fluidized bed Simulation Silicon carbide Particle behavior

Hwang H, Mun J, Kim J, Korean Chem. Eng. Res., 58(3), 381 (2020)
Shahabuddin M, Alim MA, Alam T, Mofijur M, Ahmed SF, Perkins G, Sustain. Energy Technol. Assess., 47, 101434 (2021)
Kalogirou S, Appl. Energy, 76(4), 337 (2003)
Almendros-Ibáñez JA, Fernández-Torrijos M, Díaz-Heras M, Belmonte JF, Sobrino C, Sol. Energy, 192, 193 (2019)
Park SH, Kim S, Kim SW, Sol. Energy, 232, 388 (2022)
Seo SB, Go ES, Ling JLJ, Lee SH, Renew. Energy, 193, 23 (2022)
Seo SB, Ahn H, Go ES, Ling LJJ, Siambun NJ, Park Y, Lee SH, Biomass Conv. Bioref., March(2022).
Jiang K, Du X, Zhang Q, Kong Y, Xu C, Ju X, Renew. Sust. Energ. Rev., 150, 111479 (2021)
Park SH, Yeo CE, Lee MJ, Kim SW, Processes, 8(8), 967 (2020)
Park SH, Kim SW, Korean Chem. Eng. Res., 59(2), 239 (2021)
Atsonios K, Nikolopoulos A, Karellas S, Nikolopoulos N, Grammelis P, Kakaras E, Chem. Eng. Sci., 66(17), 3979 (2011)
Bandara JC, Jayarathna C, Thapa R, Nielsen HK, Moldestad BME, Eikeland MS, Chem. Eng. Sci., 227, 115917 (2020)
Zhou Q, Wang J, Chem. Eng. Sci., 122, 637 (2015)
Liang Y, Zhang Y, Li T, Lu CA, Powder Technol., 263, 121 (2014)
Lee JM, Kim DW, Park KI, Lee KH, Korean Chem. Eng. Res., 58(4), 642 (2020)
Go ES, Kang SY, Seo SB, Kim HW, Lee SH, Korean Chem. Eng. Res., 58(4), 651 (2020)
Lim JH, Lee DH, Korean Chem. Eng. Res., 55(5), 698 (2017)
Liu H, Cattolica RJ, Seiser R, Chem. Eng. Sci., 169, 235 (2017)
Lim JH, Bae K, Shin JH, Kim JH, Lee DH, Han JH, Lee DH, Powder Technol., 288, 315 (2016)
Kim SW, Korean Chem. Eng. Res., 57(1), 105 (2019)
Johnsson F, Zijerveld RC, Schouten JV, Van den Bleek CM, Leckner B, Int. J. Multiph. Flow, 26(4), 663 (2000)
Kunii D, Levenspiel O, Fluidization engineering, 2nd ed., Butterworth- Heinemann, Boston(1991).
Tregambi C, Chirone R, Montagnaro F, Salatino P, Solimene R, Sol. Energy, 129, 85 (2016)
Kim SW, Kim SD, Int. J. Heat Mass Transf., 64, 269 (2013)
Calderón A, Barreneche C, Palacios A, Segarra M, Prieto C, Rodriguez-Sanchez A, Fernández AI, Energy Storage, 1(4), e63 (2019)