Proposal for a teaching demonstration Stand Thermoelectric Effect

Proposal for a teaching demonstration Stand Thermoelectric Effect
Proposal for a teaching demonstration Stand
Thermoelectric Effect
Oswaldo Hideo Ando Junior *1, Cleber Lourenço Izidoro2, João Mota Neto3, Mario Orlando Oliveira4,
Lirio Schaeffer5
Department of Electrical Engineering, Faculdade SATC
Criciúma, Santa Catarina, Brasil
*[email protected]; 2 [email protected]; [email protected]
Energy Study Center to Development (CEED), National University of Misiones –UNaM,
Oberá, Misiones, Argentina.
[email protected];
Mechanical Transformation Laboratory, University Federal of Rio Grande do Sul - UFRGS
Porto Alegre, Rio Grande do Sul, Brasil
[email protected]
Abstract
interaction and direct contact with the student. [1]
This article presents a proposal for development of a
didactic strand for demonstration of the Seebeck, Peltier
effects and for testing to obtain performance curves of the
modules and thermoelectric materials. Thermoelectric
materials have the property that when subjected to a
potential difference to generate a temperature gradient
between its faces (Peltier) and subjected to a temperature
gradient, generating a potential difference between their
terminals (Seebeck). The stand proposal is composed of a
thermal system that has the functions of heating and cooling
followed by a data acquisition system (temperature, voltage,
current and power output) which will allow the
visualization of measured quantities in the form of graphs
and a software developed in Delphi® that enable monitoring
the effects during the experiments and obtain the
performance curves of thermoelectric materials. Ends up
presenting a prototype of the bench didactic proposal and
the validation results of the bench.
One way to check the level of learning in the
classroom is through the use of teaching resources
technology that enables academic develop practices or
experiments related to the content covered in class,
and one of these ways is the use of didactic
countertops.
Keywords
Didatic Stand, thermoelectric, Peltier Effect, Seebeck Effect,
Learning.
Introduction
One of the major paradigms of education is to attempt
to change the archaic form of the learning process. As
can be seen in most educational institutions a lesson
always comes down to the traditional method,
students listening and speaking teacher, very few
times using other tools to verify the contents
assimilated. Like for example, through practical
examples, use of teaching resources technological
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The object of this paper are thermoelectric materials,
these materials when subjected to a temperature
difference generates electricity. So as we can see there
are several quantities that can be analyzed to confirm
these effects, such as temperature, voltage and current
generated. [2]
To visually analyze all this greatness, we need to
measure this information, in this case, there will be a
didactic stand for the academic and perform tests by
varying temperature proves the power generation, the
effect of thermoelectricity.
Therefore, this paper presents the development of a
didactic stand low cost to enable the student to prove
the concepts discussed in the classroom through
practical experiments.
It is noteworthy that the thermoelectric materials can
be applied in various branches of engineering as:
renewable energy, the very study of physics, among
other applications. Therefore, using the counter
proposal able to demonstrate that the student from
thermal variations on the thermoelectric material has
1
as a result the variations of electrical measurements,
such as voltage, current and power.
Thermoelectric effects
The thermoelectricity is the property that some
materials have to generate electricity based on the
temperature difference applied to its terminals and
vice versa. Two phenomena can be studied to better
understand the functioning of these materials, the
Seebeck effect and the Peltier effect.
Seebeck Effect
The thermoelectric effect was discovered in 1821 by
Thomas Johann Seebeck (physicist born in 1877 and
died in 1831), which states that: when two distinct
conductive material is applied to a temperature
difference can generate a potential difference (voltage)
between their terminals, as is shown in Figure 1A. If
there is a load on the output of this material an electric
current is generated, as shown in Figure 1B.
This phenomenon is called the Seebeck coefficient (α),
one can observe this phenomenon in a well-known
device, the thermocouple element used for
temperature measurement:
α=
∆V
∆T
FIG. 2 PELTIER EFFECT [3]
The quantification of this effect is the Peltier coefficient
(π):
π = α .T
(2)
Thermoelectric Materials
Thermoelectric materials are semiconductors that
formed when applied to temperature differences can
generate energy in the form of electrical voltage.
Thermoelectric modules are typically formed of
semiconductor materials, and has its structure formed
to increase the current density and hence the output
power. Are manufactured from materials such as
tellurium, antimony, germanium and silver, with high
doping to create semiconductor materials. These in
turn are welded in a sandwich of two ceramic plates,
ensuring heat transfer and sufficient mechanical
strength. Figure 3 shows how the formation of the
tablet, with PN junctions connected in series.
(1)
α ⇒ Seebeck Coeficient
∆V ⇒ Voltage Range
∆T ⇒ Temperature Range
FIG. 3 FORMATION OF THE THERMOELECTRIC MODULE [3]
FIG. 1 SEEBECK EFFECT [3]
Years later, another physicist, Jean Charles Athanase
Peltier (born in 1785 and died in 1845) described a
metal junction can produce cold or heat, the Peltier
effect. The Peltier effect provides that two distinct
materials when subjected to a potential difference does
occur producing temperature gradient, namely the
inverse process to the Seebeck effect.
Depending on the direction of current heat can be
released or absorbed, as can be seen in Figures 2A and
2B.
2
By applying a temperature greater on one side there is
a current flow constant over the semiconductor
material, and therefore a voltage formed by the
association of several elements.
All commercial thermoelectric modules are based on
the principle mentioned above, these modules are
manufactured for different values of temperature, size
and power, Figure 4 shows a commercial tablet.
FIG. 4 COMERCIAL THERMOELECTRIC MODULE [3]
Among the advantages of thermoelectric materials, we
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can list the high reliability, low maintenance,
application versatility, size, lightness, is silent and
highly secure. [5]
With the development of thermoelectric materials, one
can apply it in various areas where there are operating
conditions. For example, can be used for power
generation in industries where heat loss is present
(thermoelectric power plants, foundries), or even in
the exhaust of a car. In these two cases, there may be a
considerable increase in overall system efficiency.
In other cases its use applies in cooling of foodstuffs,
electronics and air conditioning systems (but we
should consider that the cooling efficiency is still low
compared to existing devices today such as
compressors). [6]
Brief State Of The Art
We highlight below some work related to the
measurement of thermoelectric phenomena.
Study platform for intelligent control applications
and embedded systems
The platform studies in question proposes the remote
programming of a microcontroller to perform the
temperature control, which via a thermoelectric
module makes it possible to remotely check the
heating of an aluminum disk and cooling module
through a blower , it will be possible to apply some
theories as PID or fuzzy control. Figure 5 shows the
schematic of the process.[7]
signals through analogue instruments (multimeters), a
power source and a thermal camera can make the
analysis of thermoelectric effects. Figure 6 shows the
bench and equipment used. [8]
FIG. 6 DIDACTICAL STAND FOR THE STUDY OF
THERMOELECTRIC GENERATORS [7]
Mini-laboratory educational for experimental studies
to the concept of renewable energy
As can be seen in Figure 7, this bench has the function
to study the various phenomena of renewable energy,
such as thermoelectric, photovoltaic, solar, among
others. As this bench encompasses many different
technologies, there is also the possibility of the study
of thermoelectric materials for waste energy, even
where there is the possibility of combining other
renewable energy technologies for analysis. [9]
FIG. 7 MINI-LABORATORY EDUCATIONAL FOR
EXPERIMENTAL STUDIES TO THE CONCEPT OF RENEWABLE
ENERGY
Propose Didatic Stand
The proposed workbench is that it is mobile, easy
installation and configuration, and has concentrated
all measurements in one device, ie, a complete system
(hardware and software).
FIG. 5 PLATFORM FOR INTELLIGENT CONTROL
APPLICATIONS [7]
Didactical Stand For The Study Of Thermoelectric
Generators
The counter of didactic for the study thermoelectric
generators has the function check the power output
signal and monitor the temperature gradient. The
system comprises a thermoelectric module, heat sinks
and resistors calibrated load, and by measuring
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With the proposed bench you can monitor the
following thermoelectric effects, among which we can
highlight the Seebeck effect, Peltier and Thomson.
While in the area of testing will allow the lifting of the
curve real performance thermoelectric modules for
various applications for cooling and power generation,
since the proposed system will have the ability to
make the purchase and storage of test data for future
comparative analyzes.
Among the possible configurations possible and
3
experiments to be carried out with the counter
proposal is the schematic layout shown in Figure 8, in
this case the application is to use thermoelectric
modules for power generation. Where one can see the
existence of a power source which can be obtained
from waste energy, for example, and a cold source
system that may be a finned heat transfer or heat pipe,
and finally a thermoelectric module that loads can
feed as resistors or battery charging systems and LED
lighting.
The experiment consists in checking the electrical
signals of the generator (voltage, current and power)
as a function of temperature variations, which through
the system data acquisition countertop (dotted lines)
you can take a measurement and demonstrate the
effectiveness of this application.
a signal for temperature and one for high temperature.
These temperature sensors operate on the Seebeck
effect to generate, when subjected to certain delta
temperature, a small amount of voltage (usually at the
home of mV), a value proportional to the temperature.
[10]
Operation Of Temperature Board
For this project we will use a type K thermocouple,
which can handle temperatures from -270 to 1200 ° C.
As the thermocouple generates very small voltages, in
his mili volts and also does not have a linear curve,
you need a signal conditioner, which linearize and
amplify the signal. [11]
In the market there are some types of conditioners,
amplifiers, for this project we opted to use the
MAX31855K of Maxim, which captures the signal
from the thermocouple and through synchronous
serial communication microcontroller sends the
temperature signals and failure, as shown in table 01.
TABLE 1 SENT BIT MAP [12]
FIG. 8 INSTALLATION METHOD OF STAND
To study the effect thermoelectric some quantities
must be considered, for example the temperature
gradient, the voltage generated, current generated,
and thus the generated power.
The proposed acquisition system is shown in Figure 09,
which basically consists of the following parts:
Electronic System Microprocessor for temperature
acquisition;
Electronic microprocessor system for acquiring
electrical quantities (voltage, current and power);
Software acquisition.
FIG. 9 SYSTEM OVERVIEW
Temperature Acquisition
According to Figure 9, the plate 01, possesses certain
temperature for acquisition of thermocouples, the
design idea is that up to eight temperature
measurements are divided into four channels, namely
4
Electric Aquisition
To acquire the electrical signals need to raise the
voltage and current of differential form, ie, the
reference signal is different plate reference signal
measurement. For this you will need to design an
electronic circuit with operational amplifiers in setting
Subtractor in order to adjust the gain value pair that
the microcontroller can start reading.
For measuring the electric voltage was made
adjustment gain amplifier for the same voltage input is
placed at the output, besides the possibility of scaling,
making possible to measure voltages up to 15V.
As for the electric current, can be used the same circuit,
only using a charging resistor (shunt) and by adjusting
the gain can be measured at the output of the circuit
the same value of input current, for example, if the
current is 100mA, the output has a voltage of 100mV.
In this case we can measure currents up to 5A
generated by the thermoelectric modules.
Acquisition System
To total data acquired visually, is a software
developed in Delphi© visual environment that will
capture information from microcontroller through the
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serial port, it will show through graphics can still save
these acquisitions for future research or compare
values.
Main Display
Figure 10 shows the main screen of the software, it
shows four different graphs, the first shows the
temperature value, in this case the temperature of the
joint red hot in blue and black CJ the resultant of these
two values (gradient) .
The second graph shows the voltage generated in
Volts, the third current in Amperes and the latter the
result of these two values, the Electric Power
generated in the module in Watts.
acquisition boards.
Always one sequence will be performed as described
in Figure 12, the first plate receives an information
from the computer case if the received information is
an application temperature, the card sends a feedback
to the microcomputer which makes the analysis of
information and aggregation via graphs.
If information is not received temperature value, this
is passed on to the next plate, which makes analysis of
receipt if a value of voltage or current, as will be sent
back to the computer.
FIG. 10 MAIN DISPLAY OVERVIEW
Software Menus
Through the program menu settings may be made as:
save, save as, communication settings and acquisition.
Figure 11 shows the configuration screen graphics,
which has the function to adjust the full scale of the
graphics and qualification or otherwise of each
channel individually, because in some cases there will
be variations in the magnitude values and
measurements that will be made.
FIG. 12 MAIN DISPLAY OVERVIEW
Expected Results
The tool will become invaluable for experimental
analysis of processes related to thermoelectricity
because all monitoring will be concentrated in only a
system of acquisition, in addition to being mobile, easy
to install and use. Another important factor is that the
storage of information brings great possibilities for
further comparison of tests and analysis for various
values of temperature gradient.
One way is to use the bench to obtain efficiency curves
of thermoelectric modules. Each type of module can
respond developed differently according to the
temperature or type of material with which it was
manufactured. Through performance tests you can
then make comparisons for each type of application
and instantly get your performance.
FIG. 11 CONFIGURATION MENU
Flowchart Of Operation
Communication between devices always starts with
the computer sending the information to the
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With its use will be possible to create various thermal
and electrical arrangements in order to obtain
experimentally that the topology with better efficiency
for a particular application, either for cooling or
generating electricity.
5
Conclusions
inteligente e sistemas embarcados”. VII SBAI/ II IEEE
This article presents a proposal for development of
a didactic bench for demonstration purposes using
thermoelectric thermoelectric modules for this
purpose.
LARS. São Luís, setembro de 2005.
[8] BOBEAN, Crina; PAVEL, Valentina; et al. “Didactical
stand for the study of thermoelectric generators”.
Buletinul AGIR n. 3/2012.
Through this workbench the student will have
complete autonomy to do practical experiments
involving thermoelectric modules, make arrangements
thermal and electrical (connected in series or parallel),
variation of loads (resistors, motors or LEDs), and
through the acquisition system generate graphs
tracking and aggregation of data, and demonstrate
through experiments the subjects covered in the
classroom.
[9] YILDIZ, Faruk; COOGLER, Keith L. “Design and
REFERENCES
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[10] Moreira, Lúcia. “Medição de temperatura usando-se
termopar. Revista Cerâmica Industrial". Volume 7, p. 5,6.
Setembro/Outubro, 2002
Pirométrica.
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[1] MORAN, J.M. Os novos espaços de atuação do professor
com as tecnologias. IN:Anais do 12º Endipe – Encontro
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par/termopares.html. Acesso em 05/03/2013.
[12] Maxim Semiconductor, Datasheet. “MAX31855 ColdJunction
Thermocouple-to-Digital
Converter”. Maxim Semiconductor, 2012.
universal:
Diversidade, mídias e tecnologias na educação”. vol 2,
AUTHOR’S INFORMATION
Curitiba, Champagnat, 2004, páginas 245-253.
Oswaldo Hideo Ando Junior graduated in
Electrical Engineering and Specialization in
Business Management from the Lutheran
University of Brazil - ULBRA with a Masters in
Electrical Engineering at the Federal University
of Rio Grande do Sul – UFRGS. Teacher of
Electrical Engineering, Faculty SATC. Reviewer
ad hoc FAPESC and PMAPS. Working mainly in the areas: Energy
Conversion, Power Quality and Power Systems.
[2] NASCIMENTO, A. et al. “Fontes Alternativas de Energia
Elétrica: Potencial Brasileiro, Economia e Futuro. Bolsista
de valor”. Revista de divulgação de Projeto Universidade
Petrobras e IF Fluminense. v. 2, n. 1, p.23-36, 2012.
[3] CAMPOS, D. N.; OLIVEIRA, T. C.. “Controlador de
Temperatura Microprocessado Utilizando Célula Peltie”r.
Cleber Lourenço Izidoro graduated in
Technology Industrial Automation from the
University of Southern Catarinense (2006)
and Specialization in Industrial Automation
and Technology Center for Automation and
Informatics (2007). Professor of Faculty SATC.
He has experience in Robotics, Mechatronics
84 f. Monografia(Engenharia Elétrica). Universidade
Gama Filho. Rio de Janeiro, 2011.
[4] SOUZA D. H.. “Otimização do Uso de Refrigeradores
Termoelétricos em Processos de Refrigeração”. 59f.
Monografia(Engenharia
Mecânica)
Universidade
de
Brasília, Brasília, 2007.
[5] FARIAS, Sandro Ricardo Alves. “Protótipo de um
microgerador termoelétrico de estado sólido: cogeração a
gás”. 2009. 98 f. Dissertação (Mestrado) – Universidade
Federal do Rio Grande do Norte. Natal, 2009.
[6] RIFFAT, S.B.; MA, Xiaoli. “Thermoelectrics: a review of
present and potential applications”. School of the Built
Environment, The University of Nottingham. Dez. 2002.
[7] ARAÚJO, Tomás V. G. P. ; FILHO, Carlos A. S.; et al.
“Plataforma de estudo para aplicações de controle
6
Compensated
and Automation.
João Mota Neto graduated in Industrial
Automation Technology at the University of
Southern Santa Catarina and master's degree in
mechanical engineering - UFRGS. Teacher of
electrical
engineering
and
industrial
automation technology in the Faculty SATC
Developing research in the areas of energy
efficiency, instrumentation and automation.
Mario Orlando Oliveira (M’09) was born in
Capiovi, Misiones, Argentina, on May 13,
1979. He received the Eletromechanical
Engineering degree from the National
University of Misiones (UNaM), Argentina, in
JOURNAL TITLE - MONTH YEAR
2005 and M.Eng. degree from the Federal University of Rio Grande
do Sul (UFRGS), Porto Alegre, Brazil, in 2009. Currently, he is
researcher of the Energy Study Center to Development (CEED) and
auxiliary professor of the UNaM. His research interests include
electrical machines protection and modeling, faults detection and
location.
Lirio Schaeffer Ph.D. in Mechanical Forming
Rheinisch
Westfalischen
Technischen
Hochschule / Aachen, R.W.T.H.A., Germany.
Professional performance: Coordination of
Improvement of Higher Education Personnel,
CAPES, Brazil. 2003 -Present – Relationship:
Employee Department of Metallurgy, UFRGS,
Brazil.1974 - Present - Public Servants, Functional Placement:
Teacher, Exclusive Dedication.
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7
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