Section 1 is the 8m inlet hose, Sections 2 and 3 are the ISC, Section 4 is the exhaust hose

Temperatures defined above are T.in (outlet of refrigerator), T.t (ISC wall temp), and T.ext (hot-day in Brookhaven

These are the different dimensionless parameters based on the geometry of each section

This is an iterative solution which 'guesses' the outlet temp, until the output of T.ln equals Tube.n. This case is recursive, the output of T.ex4 is the 'wall temp' of the input. To change inlet temperatures requires re-iterating thru this set of equations...