Heat transfer model of a solar receiver-reactor for the thermal dissociation of ZnO—Experimental validation at 10 kW and scale-up to 1 MW

A transient heat transfer model is developed for analyzing the thermal performance of a thermochemical reactor for the solar-driven dissociation of ZnO in the 1600–2136 K range. The reactor consists of a rotating cavity-receiver lined with ZnO particles that are directly exposed to concentrated solar radiation. The model couples radiation, convection, and conduction heat transfer to the reaction kinetics for a shrinking domain and simulates a transient ablation regime with semi-batch feed cycles of ZnO particles. Validation is accomplished in terms of the numerically calculated and experimentally measured temperature profiles and reaction extents for a 10 kW reactor prototype tested in a high-flux solar simulator and subjected to peak solar concentration ratios exceeding 5000 suns. Scaling-up the reactor technology to 1 MW solar thermal power input has the potential of reaching a solar-to-chemical energy conversion efficiency of 56%.