Using Advanced Sensors With VEX — the Peltier Effect
By Daniel Ramirez
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In this issue, we are going to continue where we left off from the previous installment in May by investigating the Peltier Effect and continuing to use the LM34 temperature sensor to learn more
applications for it. We will utilize a heat pump that’s
commonly used for air conditioning with the LM34
functioning as a thermostat.
HVAC (heating, ventilation, and air conditioning) refers
to the systems that provide comfort in areas where
temperature sensing plays an important role. Heating homes
and monitoring stoves and hot water heaters, for example,
all require a thermostat to control the temperature. The
same goes for air conditioners, refrigerators, and freezers.
We can control the temperature of a heating pad, as we
The Peltier Effect sounds like it should be the title of a Sci-Fi film. Movies like
Frankenstein, The Man in the White Suit, and, of course, The Absent Minded Professor
and Son of Flubber, were actually full of technological wonders for their time, with
various lighting effects and sparks generated from Tesla coils, Van de Graff generators,
Jacob’s Ladders, and also for the bubbling chemicals in beakers and glass tubes in all
kinds of shapes and colors.
FIGURE 1. This is what a Peltier
heating/cooling pad looks like.
will see below. This pad will be useful (especially in a high
school or college lab) when precise temperature control is
needed for an experiment. I’ll show you how to obtain
precise heating and even cooling of liquids using some
inexpensive components, with VEX orchestrating the entire
Standard lab gas-powered Bunsen burners do not have
very accurate temperature control. In order to incubate
samples in food processing, biology, and medicine, accurate
temperature control is needed. Otherwise, the samples can
be destroyed. Think of the heating thermostat in an
aquarium. The tropical or cold water fish depend on a
specific range of temperatures. If these are exceeded, then
they will suffer. The same goes for us humans.
What is the Peltier Effect?
The Peltier Effect is used in heat
pumps for heating and cooling
applications. Thermoelectric cooling
uses the Peltier Effect to create a
heat flux between the junctions of
two different types of materials. A
Peltier cooler, heater, or
thermoelectric heat pump is a solid-state active device which transfers
heat from one side of the device to
the other (against a temperature
gradient from cold to hot) when
current is passed around the circuit.
We will explore both heating and
cooling applications of a Peltier
device in the two experiments
FIGURE 2. These TEC pads are stacked into
this assembly which generates more heat;
it can also cool to lower temperatures than can
be accomplished using a single pad.
58 SERVO 07.2012