=

If in this formula we make F 1, we get n = 36, which shows that to remove the heat of fermentation 1 ton of refrigerating capacity is required for every 36 barrels of beer. This applies to strong beers. For weak beers, 1 ton of refrigerating capacity may suffice for 50 or 60 barrels. For rough and preliminary estimates, 25 barrels are usually allowed per ton of refrigerating capacity.

REFRIGERATION REQUIRED TO KEEP THE

TEMPERATURE OF THE ROOM.

The refrigeration required to keep the room at a constant temperature is computed by means of the following general formula:

H=cA (tt1),

(136.) Art. 1543.

in which H = B. T. U. of refrigeration required to maintain a given space at a certain temperature t,, when this space is separated from another, in which the temperature is t, by a surface whose area in square feet is A ; and c = constant depending upon the material and thickness of the substance. separating the two spaces. The value of the constant generally varies between 2 and 5. For rough estimates, it may be taken as equal to 3.

The preceding refrigeration may be reduced to tons by dividing by 285,300; that is, the amount F of refrigeration, expressed in tons, is

F

CA (t-t)
285,300

= .000003505 c A (t −t ̧).

(137.) Art. 1543.

Table 33 contains values of c as given in Siebel's Mechanical Refrigeration.

For double floors and ceilings, air-tight and well filled, so as to prevent the ingress of air, c may be taken as 2. When a room is separated from the outside by a hermetically closed air-space between two walls, the value of c for the outside wall may be used in the formula, but instead of the temperature t1, a mean should be taken between t, and t, which is equivalent to using (t − t) instead of t — t1.

For a wall consisting of several materials, the coefficient c may be found from the formula

in which b1, b, b,, etc., are the thicknesses, and c1, c2, c,, etc., the corresponding values of c for the several materials composing the wall.

In large cold-storage warehouses of 250,000 cubic feet or over, 1 ton of refrigeration will maintain 10,000 cubic feet of well-insulated space at a temperature of 30°, and 5,000 cubic feet at 15°. In small warehouses of 50,000 to 100,000 cubic feet capacity, 1 ton of refrigerating effect will maintain 6,000 cubic feet at cold-storage temperatures, and 3,000 at freezing temperatures. These figures do not include the refrigeration required to cool the goods.

REFRIGERATION REquired to COOL THE ARTICLES. The amount of refrigeration required to reduce the goods from their temperature † to the temperature t, of the room is given by the formulas.

H = (w,s,+w, s2 + w, s2 + . . . . ) (t − t),

2 2

3

(139.)

Art. 1545.

.000003505 (w, s, + w2 S2 + W3 $3 + ··· .) (tt), (140.)

1

2 2

Art. 1545.

in which w,, w,, etc., are the weights in pounds of the different kinds of produce to be cooled, s,, s,, etc., their corresponding specific heats, and H and Fare refrigeration units in B. T. U. and tons of refrigeration, respectively.

TONS OF REFRIGERATION REQUIRED.

If the weights of carcasses of different kinds are represented by w1, W21 ᏃᏪ . etc., and the number of carcasses of each class by n1, n,, n,, etc., the weights to be cooled will

19

39

721937

ben, w1, n, W2, Nz W' 39 etc. Substituting these values

2

3

for w1, w, etc., in formula 140, and putting t- t,= 95°

=

35° 60°, we get, for the tons of refrigeration required,

F.000003505 (n, w, s,+n, w, s2+.

2

.) × 60

.). (141.)

Art. 1557.