PASCO SE-8575 VISIBLE STIRLING ENGINE - Manual (Page 9)

5
012-06055A The Visible Stirling Engine
®
Experiment
Equipment needed
– Model SE-8575 Visible Stirling Engine
– (2) Styrofoam cups
– Thermometer
– Hot water (boiling is preferred )
– Paper towels to wipe up water
– Optional: Basic Calorimetry Set (TD-8557)
Purpose
The purpose of this experiment is to get a physical feel for the loss mechanisms in any engine.
Theory
Engines are made to do something. They take in energy from a source, they reject waste heat to a
reservoir, and they do useful work. Every engine has losses. The purpose of this experiment is to
identify the loss mechanisms and determine what could be done to reduce those losses.
Setup
➀
Nest one Styrofoam cup inside the other to make a two cup calorimeter. Weigh the cups.
➤ NOTE: The TD-8557 styrofoam Calorimeter works well to replace the cups.
➁
Fill the cups half full with very hot water. Put a lid over the assembly and weigh it again.
➂
Measure the temperature of the water. Convert the temperature to Kelvin or Rankine.
➃
Measure the temperature of the air in the room. Convert this temperature to Kelvin or Rankine.
➄
Place the engine on top of the hot water and start it. After it gets up to speed stop the engine and
turn it slowly by hand. Watch what happens to the piston when the air shifts from the hot side to
the cold side.
Calculation
Calculate the theoretical efficiency of the engine operating between these two temperatures using
the following formula.
temp hot – temp cold
temp hot
×
100 = % efficiency
What is the theoretical efficiency of a Carnot engine operating between these temperatures?
Questions
➀ Which would do more for efficiency of the engine, raising the temperature hot by 50°, or
lowering the temperature cold by 50°?
➁ The hot water in the cups is a form of stored energy available to do work. Would it be possible
to run a car on very hot water?
➂
How much energy is stored in the hot water?