Calcul de la formation de glace dans les conduites forcées

The calculation of ice formation in penstocks

Chargé de cours à l'Ecole Nationale Supérieure des Mines de Saint-Etienne; Chef du Département Recherches de la Société B.V.S.

Résumé

A close penstock heat balance analysis allowing for the main heat energy elements makes a clean sweep of the old empirical formula involving the non-freezing of a penstock. The true picture is very much more complicated. According to [1] the basic heat energy elements are expressed by formula (1) to (10). The heat balances of the moving water and the ice-coated walls are given by formula (11) and (12) respectively, with the five following independent variables: r*, Oe, H, x, t Differentiating Oc from (12) with respect to x yields formula (13), and after replacing the physical constants by their values in the calorie-metre-degree Centigrade-metric ton-hour system, the final formula, (14), is obtained, which unfortunately cannot be integrated. Bogoslovsky [1] gives a sufficiently accurate graphical solution for industrial requirements, which has been confirmed experimentally in situ on several occasions ([2] and [3]). Table 1 enables this graphical solution to be applied very quickly. Figures 1 to 3 show a practical application of the method to a numerical example taken from industrial practice. Practical rules derived from long experience are given in condensed form in chapter V.