PASCO TD-8564 THERMAL EFFICIENCY APPARATUS - Manual (Page 17)

012-05443A Thermal Efficiency Apparatus
13
Experiment 2: Heat Engine Efficiency (Detailed Study)
EQUIPMENT NEEDED:
— Thermal Efficiency Apparatus — 1 DC power supply capable of 2.5 A at 12 V
— ohmmeter — patch cords
— ammeter (up to 3 A) — 2 voltmeters
— 3 kg — (7 lbs) ice and a bucket for the ice-
water bath
Introduction
In this experiment the user will determine the actual efficiency and the Carnot efficiency of
the heat engine and then compensate for the energy losses to show that the compensated
actual efficiency approaches the Carnot efficiency.
Initial Setup
➀
Prepare the ice-water bath and immerse both rubber tubes from the Thermal Efficiency
Apparatus into the bath (Figure 4).
➁
Plug the 9V transformer into the wall socket and into the pump on the Thermal Efficiency
Apparatus. You should now hear the pump running and water should be coming out of the
rubber hose marked “out”.
➂ Plug the ohmmeter into the thermistor terminals.
Modes of Operation:
To obtain all the necessary data for the heat engine it is necessary to run the Thermal
Efficiency Apparatus in two different modes. The Heat Engine Mode determines the actual
efficiency of the Peltier device. The Open Mode determines the losses due to conduction
and radiation. Data from both modes is used to calculate internal resistance and the Carnot
Efficiency.
➀
Heat Engine
A. Connect a DC power supply and a voltmeter and ammeter to the heater block terminals.
Turn on the voltage to about 11 V.
➤ NOTE: This is just a suggested value
chosen to make the hot temperature nearly
at the maximum allowed. Any voltage less
than 12 V is suitable. The Thermal
Efficiency Apparatus should not be run
for more than 5 minutes with the hot side
above 80°C. A thermal switch will
automatically shut off the current to the
heater block if it exceeds 93°C to prevent
damage to the device.
Figure 2.1
Ω
V
V
A
Power
Supply
0.5 Ω
1
Ω
2
Ω