In this experiment, the heat engine consists of an aluminum canister
connected by tubing to a piston. The work is done by the air inside the
system which expands when it is immersed in hot water. The expanding air
pus
...
In this experiment, the heat engine consists of an aluminum canister
connected by tubing to a piston. The work is done by the air inside the
system which expands when it is immersed in hot water. The expanding air
pushes on a piston and does work by lifting a weight. The heat engine cycle is
completed by immersing the can in cold water, which returns the air
pressure and volume to the starting values.
A
The theoretical maximum efficiency of a heat engine depends only on the
temperature of the hot reservoir TH and the temperature of the cold
reservoir TC . The maximum efficiency is given by
e
max=(1−T TC H)× 100 (1)
The actual efficiency is defined as
e=
WQH
× 100 (2)
where W is the work done by the heat engine on its environment and
QH is the heat extracted from the hot reservoir.
We will use Equations 3-5 below to analyze our heat engine.
According to the First Law of Thermodynamics,
ΔU=Q−W (3)
where ΔU is the change in internal energy of the gas, Q is the heat
added to the gas ( Q is negative when heat is removed), and W is the
work done by the gas ( W is negative when work is done on the gas).
7/8/2015 1:53 PM
The Heat Engine
Lab
20
1P H Y S I C S L A B O R A T O R Y M A N U A L
You may recall that the equation relating the heat to the temperature change
for a substance of heat capacity C is
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