Solar test of an integrated sodium reflux heat pipe receiver/reactor for thermochemical energy transport

A chemical reactor for carbon dioxide reforming of methane was integrated into a sodium reflux heat pipe receiver and tested in the solar furnace of the Weizmann Institute of Science, Rehovot, Israel. The receiver/reactor was a heat pipe with seven tubes inside an evacuated metal box containing sodium. The catalyst, 0.5 wt% Rh on alumina, filled two of the tubes with the front surface of the box serving as the solar absorber. In operation, concentrated sunlight heated the front plate and vaporized sodium from a wire mesh wick attached to the other side. Sodium vapor condensed on the reactor tubes, releasing latent heat and returning to the wick by gravity. The receiver system performed satisfactorily in many tests under varying flow conditions. The maximum power absorbed was 7.5 kW at temperatures above 800°C. The feasibility of operating a heat pipe receiver/reactor under solar conditions was proven, and the advantages of reflux devices confirmed.