ENGINE AND BOILER TESTS.
The Steam Engine Tests are made on the high-speed Ball
engine, which operates the shops. This motor has been specially
equipped for the purpose. It receives steam from the main line
through a Sweet separator; humidity determinations are thus made
twice—once by a separating calorimeter before the steam enters
the separator, and again by a throttling calorimeter as it enters the
cylinder. It is fitted with proper indicators, and permanent indicator
rigging so that at any time cards may be taken and the indicated
horse-power determined. In like manner a rope friction brake
is so arranged that it may be at once applied for the determination
of brake horse-power. Connections are so made with a Wheeler
surface condenser that the engine may at will be operated either
condensing or non-condensing. Provisions are made for measuring
the temperatures and the amounts of the condensation water
and the condensed steam produced during the run. With these
data a complete heat balance of the experimental run is attainable.
For Steam Boiler Tests the boilers of the university heating
and lighting plant are available. The department is equipped with
the necessary apparatus—thermometers, gauges, steam calorimeters,
fuel calorimeters, gas analyzers, scales, tanks, and so on. Students
of Mechanical Engineering are taught by practical lessons in the
boiler room the standard methods for boiler trials, and the class
makes each session at least one complete trial.
The Gas Engine Tests are made on an Otto machine of 15
I. H. P. and 12 B. H. P. This is also provided with its friction
brake, indicator rigging, and indicator. The cooling water is run
in from calibrated tanks and provision is made for observing not
only its amount but the initial and final temperatures. Gasoline
or alcohol is used as fuel, and is run in from a graduated wrought-iron
bottle, so that the amount consumed is determined. The heating
power is obtained by an independent test with a Rosenhain calorimeter.
Samples of the burnt gases are drawn from the exhaust
pipe and analyzed in an Orsat gas apparatus. With these data,
and the observed numbers of revolutions and explosions, the heat
balance is worked out.
The Refrigerating Tests are made on a Remington Ice Machine
of one ton capacity. This is an ammonia compression machine
driven by an electric motor. Instead of brine, plain water is used,
heated by a steam jet to 100 degrees and then cooled down to 40
degrees by the machine. A run is first made with the pipes empty
in order to determine the friction horse-power. The ammonia is
then turned on and the run is made under load. In both cases the
power consumed is measured both by wattmeter and by ammeter
and voltmeter readings. The tanks are accurately calibrated and
careful measurements of the temperature are made through the
run. Indicator cards are also taken from the ammonia cylinders
and the number of revolutions is registered by counter. With
these data the mechanical and thermodynamic performance of the
machine are figured out.
