| Abstract: | For the investigation of internal and external heat transfer thermochromic liquid crystals (TLC's) have become a very commonly used tool. Today, mainly two different experimental methods with TLC's are in use: The steady state TLC method measuring the wall temperature according to a constant heat flux produced by a heater foil and the transient TLC method measuring the time response of the wall temperature due to a sudden change of the fluid temperature. In the present paper the two different measurement techniques are compared for a very complex 3D flow inside a 180°‐turn of a two‐pass cooling system. From theoretical considerations, the general difference in the heat transfer because of the different wall boundary conditions is shown. |
