Theoretical analysis of a solar membrane reactor with enhanced mass transfer by using helical inserts

Abstract

Product separation Pd-based membrane can boost performance of conventional solar-driven thermochemical reactors by accelerating reaction processes. However, concentration polarization due to mass transfer resistance limits the conversion and efficiency of solar membrane reactor. In this work, the helical insert-enhanced solar membrane reactor is proposed to eliminate adverse impact of concentration polarization. The influence mechanism of radial mass transfer enhancement on reactor performance is analyzed. The number of helical inserts is optimized and the performance enhancement of proposed reactor under different operating conditions is explored. It is shown that enhancing radial mass transfer effectively alleviates concentration polarization and overall methane conversion can be maximally improved by about 29 %. By applying multi-helical inserts, the radial mass transfer in reaction bed is greatly enhanced, which achieves homogenous radial component distribution, improves the hydrogen separation performance and expands high-quality reaction zone. In comparison to the original membrane reactor, the optimized reactor with 5-helical inserts can increase methane conversion, fuel efficiency, and hydrogen recovery by 16.4 %, 18.7 %, and 21.4 %, respectively, in the operating temperature range of 673–823 K. Also, it is presented that the proposed helical insert-enhanced solar membrane reactor can deliver significant performance improvement under different operating conditions.