Performance analysis on the parabolic trough solar receiver-reactor of methanol decomposition reaction under off-design conditions and during dynamic processes

Abstract

Parabolic Trough Solar Receiver-Reactor (PTSRR) of Methanol Decomposition Reaction process (MDR), which can achieve chemical storage and efficient utilization of solar energy, has gained increasing attention recently. To comprehensively study the performance of PTSRR of MDR under off-design conditions and during dynamic processes, a model of PTSRR-MDR is developed and validated. Detailed energy and exergy analysis model are developed to figure out the irreversibility distribution. Results indicate that exergy destructions caused by solar concentrating and thermochemical reaction processes limit the improvement of exergy efficiency, which account 39.32% and 18.32%, respectively, under 800 DNI. When DNI step decreases from 800 to 400 W m−2, the methanol conversion rate decreases from 90.0% to 40.9% in ∼400 s. The solar-to-chemical exergy efficiency increases from 16.39% to 32.80% immediately, then decreases to the lowest value in 30 s, and rises to 11.23%. The efficiency is lower than the stable value transiently because the exergy stored in solid phase is partly destructed when converted to chemical exergy. Then, dynamic performance under DNI step increase is studied. Due to thermal inertia, additional chemical energy and exergy are gained or lost, compared to the ideal process. The results may provide some guidance for further efficient operation control.