Operating procedures of a demonstration experiment on H2 permeation from solar thermal receivers into silicone oil

Abstract

This study investigated the operational methodology for hydrogen removal from solar thermal collector tubes. The process comprises three stages: hydrogen transport from the absorber tubes' vacuum insulation into the heat transfer fluid (HTF), transfer into the headspace gas of the expansion vessel, and venting into the atmosphere. For effective hydrogen removal, these stages must proceed at comparable rates. Operational challenges, such as blockages in the system's piping and exceeding pressure limits, necessitated system modifications. As a result, this work focuses primarily on determining the mass flow rate of recirculated HTF using time-of-flight measurements. Despite uncertainties introduced by noninvasive sensor installation and limited data logger resolution, the analysis confirmed that complete fluid recirculation is achievable within 34 minutes, allowing for multiple cycles daily without exceeding system pressure limits. Adjustments to the operating procedure further enabled continuous recirculation, enhancing overall system efficiency.