The practical application of the preceding formulæ will be shown by the following examples.
EXAMPLES.
1. A 36-inch cylinder with 51⁄2 feet stroke is supplied by a boiler evaporating effectively 60 cubic feet of water per hour, and the piston makes 20 strokes per minute without expansion;—what is the power of the engine and the pressure of steam in the cylinder?
Let it be assumed that r = 6 × 144 = 864 and m = 0·1. Since the engine is a condensing engine, we have b = 164 and e′ = 3691399. By the formulæ (25.) and (26.) we have
| H = | We′ − VA(b + r) | ; |
| 33000(1 + m) |
and since by the data we have
| W = 1 A = 7·069 V = 2nL = 40 × 5·5 = 220, |
the formula, by these substitutions, becomes
| H = | 3691399 − 220 × 1028 × 7·069 | ; |
| 33000 × 1·1 | ||
| ∵ H = 57·6. | ||
Since e = 1, the pressure P of steam in the cylinder, by (18.), is