human
and is illustrated by the advantage of stirring a liquid being heated in bulk. In the film evaporators the circulation is through tubes at high speed (up to 2 miles a minute), and the maximum effect in this sense is thus obtained. The increase in heat transference is not directly proportional to the increase in velocity, but in a lower ratio, sometimes approximately the square root of the velocity. In such a case, if either velocity be quadrupled, the heat transference is doubled. Other advantages of high velocity are that the heating steam more readily sweeps away condensed steam from the heating surface, and the high-speed film similarly
gpt
away