Growth dynamics and morphology of D 2 O + HFC-134a clathrate hydrate crystal toward tritiated water separation

This work represents the crystal growth and morphology of Deuterium water (D2O) and HFC-134a clathrate hydrate toward enhancing the hydrate-based tritiated water separation method. The utilization of the method involves the use of D2O + HFC-134a hydrate as a substrate to capture tritiated water. It is imperative to have a comprehensive understanding of the morphology of each crystal and the precise temperature and pressure conditions required for their production, given that the substrate consists of individual crystals. Experiments were conducted within ΔTsub range from 1.0 K to 7.8 K. The pressure was set at 0.305 to 0.398 MPa to avoid the liquefaction of HFC-134a. The results revealed that at ΔTsub less than 5.2 K, the hydrate crystals were plates and polyhedrons with a size of 1.0–3.0 mm. When ΔTsub exceeded 5.2 K, the crystals of columnar or dendritic morphologies were observed. They formed elongated shapes of 3.0 mm in length and 0.1 mm in width. Columnar or dendritic crystals are suitable for increasing surface area. In contrast plate and polyhedral crystals decrease the surface area of the substrate and reduce flow resistance. Selecting the favorable crystalline form to intensify the equipment and processes is essential.