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