The Flow Of Gases In Furnaces

THE SUBDIVISION OF A CURRENT OF HOT GAS

89

FIG. 47.

indicated in Fig. 47. From the preceding, it may be readily seen
that a current of hot gas which i$ giving off heat or cooling cannot be
subdivided into equal ascending currents.
When, however, the attempt is
made to subdivide the current of gas
Q into two equal descending currents
(Fig. 46), it will be completely suc-
cessful.

Assuming, for example, that the
temperature of one of these currents,
q\, should become less than the tem-
perature of the current q%. In this
case the weight of the column of gas
qi will be increased, and the velocity
of its descending motion will be in-
creased. The current of gas qi will
become stronger than #2, its tempera-
ture will gradually increase and it will

finally become equal to #2. It can be concluded from this that
the problem of subdividing a current of gas which is cooling or
giving off heat into equal descending channels may be solved
in a very simple manner, owing to the fact that there is always
a tendency for the temperatures of these descending streams to

remain uniform.

Therefore, if it is desired to sub-
divide a current of hot gas which is
cooling or giving off heat, into equal
streams, it is necessary to give these
streams a downward or descending direc-
tion of flow] or, in other words, a cur-
rent which is cooling may be subdivided
into uniform descending streams.^

(1) Accordingly, it is possible to approxi-
mate the fractional resistance in the two chan-
nels between which the current is divided,
when one branch has a higher resistance or
a higher heat loss than the other, because
the stream of gas divides itself accordingly.

In Fig. 43a, such a case is shown. The

stream of gas Q is divided into two descending streams q\ and #2, the average
temperatures of which are different, being denoted by t\ and /2. The average

FIG. 48a.