THE VERTICAL THERMOSYPHON WITH LARGE RAYLEIGH NUMBERS, PRINCIPLES AND EXPERIMENTAL CHARACTERIZATION

In this paper we remind the two categories of thermosyphon and energy balances that govern their operation. Especially for thermosyphons of second order (where the condition of mechanical equilibrium is not verified), it is established the important influe nce of the pressure losses in the air flow system according to the operation of the chimney with temperature or flux density imposed. Velocity and temperature measurements were performed for different levels of obstruction of the chimney with large Rayleig h numbers. The results obtained allow us to validate the assumptions made on circulating flows and the possible occurrence of return flows in the output sections