| P = | We′ | − b. |
| VA |
Therefore
| P = | 3691399 | − 164 = 2210; |
| 1555·18 |
which being the pressure in pounds per square foot, the pressure per square inch will be 151⁄3 lbs.
2. To find the effective evaporation necessary to produce a power of 80 horses with the same engine. Also, find the pressure of steam in the cylinder, the speed of the piston being the same.
By the formula (32.), with the above substitutions, we have
| W = | 33000 × 80 × 1·1 + 220 × 7069 × 1028 | = 1·22. |
| 3691399 |
The evaporating power would therefore be only increased 22 per cent., while the working power of the engine would be increased nearly 40 per cent.
The pressure P in the cylinder will be given, by (18.), as before.
| P = | 1·22 × 3691399 | − 164 = 2732; |
| 1555·18 |