A high temperature tubular reactor with hybrid concentrated solar and electric heat supply for steam methane reforming

Solar-powered steam methane reforming could offer an efficient avenue for hydrogen generation, therefore reducing carbon dioxide emissions. However, the current solar thermochemical reactor (STR) is subjected to the mismatch between the continuous chemical process and the intermittent solar irradiance. In this work, we proposed a novel heat pipe tubular reactor based on the high-temperature heat pipe, i.e., a high-temperature heat pipe reactor (HTPR), achieving a highly effective heat transfer and a hybrid energy supply, i.e., concentrated solar energy and photovoltaic electricity. These two heating modes enable the HTPR to achieve a round-the-clock reforming process. Firstly, the HTPR start-up performance was measured by a concentrated solar simulator and a high-frequency induction device, and the start-up time for both heating modes was only 9 min. The methane conversion and the hydrogen purity were respectively 90% and 74%, approaching the thermodynamic equilibrium of SMR. Then, the continuous operation stability of the HTPR was conducted by a hybrid energy supply, i.e., solar and electricity. The methane conversion and hydrogen purity retained 91% and 72% for 24 h, respectively. Finally, the heat and mass transfer in the reaction cavity of the HTPR was simulated. The results show that the high thermal conductivity of the HTPR is capable of supplying energy to the strongly endothermic SMR, therefore promoting H-2 yields. This work provides a new way, in the aspect of reactor design, for resolving the unstable hydrogen production by renewable energy.

Automated summary

Solar-powered steam methane reforming is an efficient way to generate hydrogen and reduce carbon dioxide emissions. The high-temperature heat pipe reactor (HTPR) proposed in this study combines concentrated solar energy and photovoltaic electricity to achieve a round-the-clock reforming process. Experimental results showed high methane conversion and hydrogen purity, as well as stable operation for 24 hours, demonstrating the potential of HTPR in resolving unstable hydrogen production by renewable energy.