In every iteration step, the average molecular weight M w , thermal conductivity λ f , dynamic viscosity µ f , and specific heat capacity c p,f of the multi-component fluid mixture are determined based on the calculated mass fractions w i from the pure component values assumed to be constant. Thereby, λ f , µ f , and c p,f are computed by mass fraction weighted averaging of the pure component data, whereas M w is determined by molar fraction weighted averaging of the component molecular weights M w,i . All required pure component properties are given in the supplementary information (SI Section S2). In addition the mixture ρ f is calculated with the ideal gas law: