Chemical Engineering Journal | 基于光-热-化学耦合模型的太阳能驱动甲烷干重整制氢反应器设计与优化

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HIGHLIGHTS

• A solar-driven hemispherical cavity reactor is designed for methane dry reforming

• Reactor performance is revealed and optimized by an optical-thermal-chemical model

• Reactors with high porosity and small pore size can achieve better performance

• Reasonably increasing CO2:CH4 feed ratio can improve optical-chemical efficiency

• Suitable power and flow rate can obtain high efficiency and low carbon deposition

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内容简介

在太阳能驱动甲烷干重整制氢过程中，反应器起到了十分重要的作用。为了提高反应器性能，本文设计并优化了一种具有复合抛物面二次聚光器和半球壳状多孔介质吸热体的腔式反应器。首先，基于蒙特卡罗光线追迹法（MCRT）和计算流体动力学方法（CFD），建立了反应器光-热-化学耦合三维数值计算模型。基于 该模型，研究了不同孔隙结构参数对反应器性能的影响规律，发现孔隙率和平均孔隙尺寸会显著影响吸热体内的太阳能分布和温度分布，但对甲烷干重整化学性能的影响较小。接着，以提高光能-化学能转化效率为优化目标，改良设计获得了一种最佳反应器，其孔隙率为0.85 ，孔直径为1 mm。接着，分析了反应物进料比、入射光功率和入口流量对反应器性能的影响规律，发现上述因素对反应器性能的影响十分显著，并且影响规律十分复杂。为了在尽可能提高光能-化学能转化效率的同时，尽可能降低碳沉积量，优选出了一种最优工况，其反应物之比CO2:CH4为1:1、入口流速为0.6 L·s⁻¹、入射光功率为3 kW。最后，在 最优工况下评估了最佳反应器的光热化学性能，发现其甲烷转化率、光能-化学能转化效率、光能-热能转化效率分别可达36.71%、30.88%、59.05%。本文研究结果可为太阳能反应器的设计和优化提供有益的借鉴。

图片摘要

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ABSTRACT

The reactor plays a crucial role in solar-driven methane dry reforming. To improve the reactor performance, a cavity reactor with a hemispherical porous absorber and a secondary concentrator was designed and optimized by developing an optical-thermal-chemical coupled model. Using this model, the effects of different pore parameters on the reactor performance were firstly investigated, finding that porosity and pore size significantly influence the distributions of solar energy and temperature but mildly influence the methane dry reforming performance. Considering the optical-chemical efficiency as the optimization objective, the reactor with the porosity of 0.85 and the pore size of 1 mm can be suggested as the optimal design. Then, the influences of the CO2:CH4 feed ratio, incident power, and the inlet flow rate were analyzed, revealing that they dramatically influence the reactor performance in complex ways. To make a compromise between the optical-chemical efficiency and carbon deposition, the operating condition with the CO2:CH4 of 1:1, the inlet flow rate of 0.6 L·s-1, and the incident power of 3 kW was selected as the optimal one. Finally, the performance of the optimal reactor was evaluated at the optimal condition, finding it can achieve quite high methane conversion ratio, optical-chemical efficiency, and optical-thermal efficiency of 36.71%, 30.88%, and 59.05%, respectively. Results from present work can provide valuable insights for the design and optimization of solar reactors.

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主要结果

Fig. 1 The designed reactor irradiated by a high-flux solar simulator.

Fig. 2 Comparison of present results and Benguerba et al.’s experiment and simulation data [57].

Fig. 3 Optical-thermal performance under different porosities (φ) and mean pore sizes (dp).

Fig. 4 Solar heat source distribution under different porosities (φ) and mean pore sizes (dp).

Fig. 5 Temperature distributions under different porosities (φ) and mean pore sizes (dp).

Fig. 6 Production rates of products and pressure drop from the inlet to the outlet under different porosities (φ) and mean pore sizes (dp).

Fig. 7 Methane conversion ratio and efficiencies under different porosities (φ) and mean pore sizes (dp).

Fig. 8 Performance under different CO2:CH4 feed molar ratios.

Fig. 9 The average temperature (Tavg) and maximum temperature (Tmax) of the absorber, and the pressure drop from the inlet to the outlet (△p) under different Pincand Vin.

Fig.10 Chemical performance under different incident power (Pinc) and inlet volumetric flow rates (Vin)

Fig. 11 Efficiencies under different incident power (Pinc) and inlet volumetric flow rates (Vin)

Fig. 12 Solar flux and heat source distributions in the optimal reactor when Pinc=3 kW.

Fig. 13 Temperature distributions in the optimal reactor.

Fig.14 Molar fraction distributions of CH4 and H2 at the vertical slice of the optimal reactor.

声 明：该文的推送已得到作者授权。

文章参考文献格式：Weichen Zhang¹, Qing Li¹, Yu Qiu*. Design and optimization of a solar-driven methane dry reforming reactor by developing an optical-thermal-chemical model [J]. Chemical Engineering Journal, 2024, https://doi.org/10.1016/j.cej.2024.149094

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