Thermal performance analysis of an integrated solar reactor using solid oxide electrolysis cells (SOEC) for hydrogen production

Concentrated solar power and solid oxide electrolysis cells (SOEC) can be combined to produce green hydrogen efficiently. However, heat loss due to fluid transport can be significant. In this paper, a volumetric receiver is first integrated with a tubular SOEC as a whole reactor to reduce the transport heat loss. Numerical investigation shows that the SOEC temperature, in a reference condition, ranges from 760 to 920 degrees C, which is qualified for regular operation. The efficiency analysis is conducted under different conditions and shows that the reactor efficiency is highly affected by the operating temperature. Therefore, increasing the incident power, decreasing the inlet velocity, or increasing the steam mass fraction would lead to a higher outlet temperature and thus a higher reactor efficiency. Based on the validated model, the integrated design presented in this paper can increase energy conversion efficiency by 2.63-30.21% compared with the separate structure, depending on the operation condition. The last section of this paper discusses the control strategy for the integrated reactor briefly, which aims to stabilize the reactor efficiency in outdoor situations. Compared with the steam mass fraction, the inlet velocity is preferred as a control variable to keep the cathode stable.