Perma Pure iCOOL - Manual (Page 5)

Section C: Principle of Operation 5
C: P
RINCIPLE OF
O
PERATION
Thank you for purchasing the Perma Pure Integrator Series Thermo-Electric Cooler.
Our ICOOL features a unique slim design leaving additional space to install or
access other sample conditioning system components. A unique shell design on
this model provides easy access to electronic board, fan and the power supply. All
electronic boards (control, relay, and display) are mounted on the front panel for
easy access.
The process of sampling combustion product stack gas or exhaust from internal
combustion engines requires a method to remove the moisture from the sample,
without removing the gas components of interest. The Integrator Series Thermo-
Electric Cooler is an ideal way to decrease the dew point of combustion gases to a
repeatable, stable, constant low dew point. The Integrator Series cooler prevents
water condensation in sample pre-filters, sample pumps, and gas analyzers. For
gas analyzers where water vapor is an interferent, a stable, repeatable dew point
becomes a part of the gas analyzer performance specification.
Perma Pure’s
Integrator Series coolers provide this constant low water concentration, resulting in
an accurate component gas measurement.
All Perma Pure coolers use thermo-electric elements (Peltier elements) to cool the
sample gas to the desired dew point temperature. A Perma Pure Thermo-Electric
Cooler is best illustrated as a
small heat pump with no
moving parts. The Peltier
elements operate on direct
current and may be used for
heating or cooling by reversing
the direction of current flow.
This is achieved by moving
heat from one side of the
module to the other with current
flow and the laws of
thermodynamics. A typical
single stage Peltier (Figure 1)
consists of two ceramic plates
with p- and n-type
semiconductor material
(bismuth telluride) between the
plates. The elements of
semiconductor material are connected electrically in series and thermally in parallel.
When a positive DC voltage is applied to the n-type thermo-electric element,
electrons pass from the p- to the n-type thermo-electric element and the cold side
temperature will decrease as heat is absorbed. The heat absorption (cooling) is
Figure 1: Thermo-electric element (Peltier)