Solar natural gas thermal dissociation, producing both hydrogen and solid carbon, appears as a promising way for progressive decarbonization of the world energy mix. Three main challenges remain to be tackled: carbon deposition issue, continuous round the clock operation of the solar reactor with an intermittent energy resource, and technology scale-up. The present work proposes a new windowless scalable solar reactor enabling volumetric gas-phase (i.e., not at the walls) methane cracking with possible hybridization. CFD simulations demonstrate the advantage of the new concept as compared to conventional tubular reactors. The proposed system uses a hot inert gas to generate a high temperature fluid zone similar to a combustion flame where the methane decomposition occurs. Based on the numerical model developed, a sensitivity study is carried out in order to optimize the reactor design enabling both high methane conversion and low carbon deposition. For methane flow-rates of 4.6 × 10^–6 kg.s^–1 and 2.3 × 10^–6 kg.s^–1 (argon flow-rate of 9.3 × 10^–5 kg.s^–1), methane conversion reached 46 and 73% for maximum fluid zone temperatures of 1676 and 1750 K, respectively. Furthermore, electric hybridization is investigated in order to highlight the potential for day and night continuous operation. Indeed, since an inert carrier gas is used as heat transfer medium, it can be heated by different energy sources to maintain the thermal power input during low irradiation periods. Thus, the solar flame concept that we previously patented proves to be of interest for practical implementation to introduce solar heat into high temperature processes.

产生氢和固体碳的太阳能天然气热分解似乎是逐步实现世界能源混合脱碳的有前途的方式。仍需解决三个主要挑战：碳沉积问题，具有间歇性能源的太阳能反应器全天候连续运行以及技术规模扩大。本工作提出了一种新的无窗可扩展的太阳能反应堆，该反应堆可实现体积气相（即不在壁处）甲烷裂解并可能进行杂交。CFD模拟证明了与常规管式反应器相比，新概念的优势。拟议的系统使用热惰性气体生成类似于燃烧火焰的高温流体区，在燃烧区甲烷发生分解。根据开发的数值模型，为了优化反应器设计以实现高甲烷转化率和低碳沉积，进行了敏感性研究。甲烷流量为4.6×10^–6 kg.s ^–1和2.3×10 ^–6 kg.s ^–1（氩气流量为9.3×10 ^–5 kg.s ^–1），甲烷的转化率达到46％和73％（最高流体区域温度为1676）和1750K。此外，为了突出昼夜连续运行的潜力，对电杂交进行了研究。实际上，由于惰性载气被用作传热介质，因此可以通过不同的能源对其进行加热，以在低辐照期间保持输入的热功率。因此，事实证明，我们先前获得专利的太阳火焰概念对于将太阳热引入高温过程的实际实施很有意义。