PASCO TD-8592 SMALL PISTON HEAT ENGINE APPARATUS - Manual (Page 17)

12
Small Piston Heat Engine 012-08375A
Hot Cold
HEAT ENGINE GAS LAW APPARATUS
Piston Dia.: 32.5mm±0.1
TD-8572
CAUTION: Max. Pres.: 345kPa. Use Gases Only DO NOT Immerse in any Liquid DO NOT Lubricate Piston or Cylinder
Pressure Port Mating Connector: PASCO Part No. 640-021
Piston&Platform Mass: 35.0g±0.6
m
If the temperature of the air trapped inside the cylinder, hose, and can is increased, then its volume will
increase, causing the platform to rise. Thus, you can increase the volume of the trapped air by moving
the can from the cold to the hot reservoir. Then, when the apple has been raised through a distance y, it
can be removed from the platform. The platform should then rise a bit more as the pressure on the
cylinder of gas decreases a bit. Finally, the volume of the gas will decrease when the air chamber is
returned to the cold reservoir. This causes the piston to descend to its original position once again. The
various stages of the mass lifter cycle are shown in Figure 5.3.
Before taking data on the pressure, air volume, and height of lift with the heat engine, you should set it
up and run it through a few cycles to get used to its operation. A good way to start is to fill one container
with room temperature water and another with hot tap water or preheated water at about 60–70°C. The
engine cycle is much easier to describe if you begin with the piston resting above the bottom of the
cylinder. Thus, we suggest you raise the piston a few centimeters before inserting the rubber stopper
firmly in the can. Also, air does leak out of the cylinder slowly. If a large mass is being lifted, the
leakage rate increases, so we suggest that you limit the added mass to something between 50 g and 100
g. After observing a few engine cycles, you should be able to describe each of the points a, b, c, and d
Figure 5.3. A schematic diagram of the incredible mass lifter heat engine
Close the shut-off valve
on the tubing from the
unused port.
The Incredible Mass Lifter Engine
The heat engine consists of a hollow cylinder with a graphite piston that can move along the axis of the cylinder
with very little friction. The piston has a platform attached to it for lifting masses. A short length of flexible
tubing attaches the cylinder to an air chamber (consisting of a small can sealed with a rubber stopper that can be
placed alternately in the cold reservoir and the hot reservoir. A diagram of this mass lifter is shown in Figure
5.2.