𝑎 𝐶𝐿 = (1 -𝜑 𝑝, 𝑠𝑤𝑒 ) 𝑎 𝑎𝑔𝑔 (52) The focus of this work is on the overlapping agglomerate particles. We utilise the derivation of the overlapping ratio, f, and the effective surface area of the catalyst layer, denoted as 𝑎 𝐶𝐿 , A rhombohedral packing density of an agglomerate is assumed with characteristics such as the number of contact points, critical porosity, packing density shown in Table . Therefore, the overlapping ratio, f, is determined from Eq. 53 and the calculated porosity of the swollen catalyst layer 𝜑 𝑝, 𝑠𝑤𝑒 in Eq. 48.