Problems with moddeling a finite difference method in Simulink?

Dear all,

For my thesis I am currently trying to develop a model, based on a finite difference method. Now I am having trouble with designing the mentioned system. The system is of a Low temperature Gasifier, that converts biomass into syngas. A lot of my models math is based of the paper "Mathematical model to predict temperature profile and air–fuel equivalence ratio of a downdraft gasification process" by Kitipong Jaojaruek.

Now I will dive on only one subpart, the energy blanace of the combustion zone:

Using the finite difference approach results in (skipping a few steps, also had it on paper so asked gpt for image, replacing some variable names):

Where I want to calculate Ti, all other variables are know, even dx is set. The inputs are u and Ts. Now I do not really know how to model it correctly in Simulink. Currently I tried to use units delays (image below) which resulted in problems, because it is not possible to get i+1. The initial condition of the integrator (T0), is a array of the length Nx (amount of points). The goal is to develop a model that simulates the temperature over time, over the length of the reactor. I am aware that i also have to integrate a relaxation factor, to make it work. But I just need someone to guide me in the right direction, before tackling the next problem.

*Ps, I saw one line not connected for the gain 2, this should also be connected to the main loop Ti.

If anyone has any reference, or can guide me the right direction, I would apreciate it. On request, I can send my current model, but it is a work in progress, so it would not add that much.