 | University of Virginia record February, 1911 |  |
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
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 watt-meter
and by am-meter and volt-meter 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.
| University of Virginia record February, 1911 | |