Objective Investigate the effect of current on the surface temperature on a
thermoelectric generator.
Examine the spatial temperature variation of the surface of the
thermoelectric generator.
Introduction The thermoelectric effect is the conversion of thermal energy into an elec-
trical current. This happens when a temperature gradient is present on a
minimum of two semi-conductor pellets, one made of a p-type material and
the other is an n-type. The pellets are joined together in series with a conduc-
tive material (usually copper) to allow electron movement between the two.
The joined pellets are referred to as a couple. The thermoelectric generator
used in this experiment has 127 couples sandwiched between two ceramic
plates. A temperature differential is applied to the plates it creates an electrical
current, but when an electrical current is applied to the unit, a temperature
differential is established between the plates. The thermoelectric generator
can operate in both directions.
Conclusion Uneven surface temperature was observed.
As time elapsed, the temperature difference between each cell increased
All currents created an exponential plot that asymptotically approached
steady state with an initial slope depending on the current.
Cells towards the edge tended to have a lower steady state temperature
than the center cells when the unit was at low current
At steady state, the cells in the center were always at a higher
temperature than anywhere else on the unit. This trend held for low and
high currents.
Cells A1-D1 and A4-D4 responded to current changes similarly;
however, as current was increased, cells A1-D1 remained much cooler
than A4-D4.
Methods A 4x4 grid was created on the thermoelectric generator
(TEC1-12706).
The unit was mounted with conductive paste on an aluminum
heat sink along with thermocouples to measure the temperature
of each cell on the grid.
Vernier software and thermocouples were utilized to gather data.
Peristaltic pump and ice water were used to keep temperature
relatively constant throughout the heat sink and cool side of the
unit without introducing heat into the system.
The thermoelectric generator was then connected to a power
supply.
Data was then gathered for a time of 150 seconds beginning with
a current of 0.25A and increasing the current by 0.25A for the proceeding trials until 2.00A was
reached.
The unit was allowed to cool down before each trial.
Effect of Current on the Surface Temperature of a Thermoelectric Generator Alfredo Flores Jr., College of the Sequoias / University of California Merced
Dr. Larry Owens, College of the Sequoias
Results
Results of the surface
temperature at each
certain current was
graphed on temperature
versus time scale.
The data was cutoff at
150 seconds for each
trial since steady state
was observed prior to
that time.
Generator at 0.25A
As the current was increased
steady state was prolonged.
Spatial temperature
differences were observed
at all currents.
Generator at 2.00A
This graph represents the
data of each run at each
current.
As the current was
increased, a greater slope
was noted at the beginning
of the trials.
Generator at 2.00A
The steady state surface
temperature were uneven at
all currents.
The cells where the wires are
attached to the unit (A1-A4
and D1-D4) were at a lower
temperature than the cells
towards the center, this was
expected since the edges were
more prone to lose heat due to
lack of surrounding cells.
Cells A1-D1 and A4-D4 did
not show an edge effect.
Steady State at 0.25A
Results (cont.)
Cells A4-D4 showed the center
temperature profile.
Steady State at 2.00A
Another view of the above
graph shows that edge A1-D1
shows the lower temperature
edge effect
Steady State at 2.00A
This Project was supported by the College of the Sequoias, SURGE project funded by the U.S. Department of Education