Okay I asked my teacher and he said I have to use this equation for the second part,

thermal resistance for a single pipe =

so

pluggiing these numbers in I get

so the overall resistance, I am not sure but Can I just use the same formula as in electrical circuits, e.g

and times that by 50, since there are 50 tubes

so R =

Is this correct?

I really need help, with the first part, since we are turning water into steam will I have to use Q = ml , for latent heat? or is it .