4. Mass transfer

To rewrite Eq. (1), the flux at the surface of the hydrate can be discretized as

$$k\_{bl}RT\ln\left(\frac{\mathbf{C}\_{Hsol}}{\mathbf{C}\_{I}}\right) = D\mathbf{V}\mathbf{C} = D\frac{\mathbf{C}\_{I} - \mathbf{C}'}{h\_{I}}\tag{7}$$

where CI is the varying surface concentration calculated locally at each surface cell, C<sup>0</sup> is the centroid concentration, and hI is the thickness of centroid surface cell, as shown in Figure 1.

Figure 1. Schematic image of discretized surface concentration.
