  A mathematical model was derived to calculate the IR reflection inside the
annulus between two concentric cylindrical tubes, where the inner side of the
outer cylinder is assumed to be coated with an IR reflected mirror. The
mathematical model is implemented in a simulation code and experimentally
validated. The experimental results of a system of two concentric cylindrical
tubes operating with an IR reflected mirror on the inside of the outer cylinder
are presented, and the results between the model and the simulation are
compared. It is seen that the correspondence is encouragingly close
(Chi-squared test p-values between 0.995 and 0.80), where the simulation
underestimates the experimental performance.
