Simulating the Dehydration Reaction of Calcium Hydroxide in an Indirect-Type Fixed Bed Reactor

Abstract

Thermochemical energy storage can be an important means to facilitate integration of renewable sources into energy supply networks. To seasonally store excess energy for use in times of high demand (e.g. winter), the reversible dehydration reaction of Ca(OH)2 appears to be a promising material for storing energy indefinitely and releasing energy as heat on demand. In this thesis, the dehydration reaction of Ca(OH)2 is investigated comparing experimental results and simulations in an indirectly heated fixed bed reactor. Dehydration by temperature increase and dehydration by pressure reduction are investigated using a 2D rotational symmetric reactor model developed in COMSOL. Additionally, a techno­economic feasibility study is performed to investigate the technology's potential in domestic applications. Results show that qualitatively the simulations can depict processes inside the reactor relatively well but quantitatively there are still major discrepancies observable. For sensible heating, the reactor model provides good results, but more work needs to be done in investigating reaction kinetics and changes in the reactor bed as result of the reaction. Considering economics, results show that for a single­family house, a Ca(OH)2 energy storage system coupled to PV panels on the roof can supply all required energy for one year to a household under favourable conditions.