Summary

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Summary

• Thermotecnical part (Valerio)
• Renewable energies
• Solar panels
• Astronomical calculations
• Electronic part (Matteo 2nd)
• Temperature sensors
• PLC and control tecniques
• Actuators

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Our project

• One of the subjects of Comenius Project is to use
  renewable energy sources applied to domotica
• Therefore we thought to project a solar panel
  plant for sanitary warm water

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• The main components of the plant are
• solar panels
• pipes
• a pump and valves
• a solar boiler
• The system will be electronically controlled in
  order to save energy

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The solar panel

• A typical flat-plate solar panel is a metal box
  with a glass or plastic cover (called glazing) on
  the top and a dark coloured absorber plate
• Sunlight passes through the glazing and the
  energy changing by solar into heat energy

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but it is possible create a solar panel also
with
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Bottles..
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Captation system

• A solution (water and nanti-freeze) flowing in
  the circuit is heated by the sun and transfers
  heat to the water contained in a storage tank
• A pump lets the water to circulate in the system.
  If the water-no frost solution temperature is
  lower than setup value, the pump is stopped and
  the heating is guaranted by hot water heated by
  gas or electric boyler

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Solar panel position (slope and orientation)

• Solar radiation catched by fixed solar panel,
  especially in north regions, is unsufficient to
  guarantee enough hot water production
• We thought to project a rotating panel able to
  follow the sun in order to maximize the solar
  radiation

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Panel slope

• The panel should be located perpendicular to sun
  direction when it is at its peak
• Sun direction changes during the year. Therefore
  in winter the panel should be almost vertical, in
  summer almost horizontal
• But in winter the radiation is weak, in summer is
  excessive, so we prefer to maximize radiation in
  spring and autumn times. In this case the angle
  of the sun is equal to the latitude. The slope of
  our panel in Modena is 44

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Chief parameters

• Latitude F angle from the equator line to our
  place location
• Modena 44,23 N
• Beckescaba 46,69 N
• Pilsen 49,74 N
• Genk 50,97 N
• Recklinghausen 51,57 N
• Kokemaki 61,26 N

F
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Panel orientation

• The fraction of solar radiation catched by panel
  depends from sun position from sun raise to
  sunset
• We calculated the angle covered by sun for each
  month. It depends from the solar declination, the
  latitude, the daylight

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Solar declination

• d angle between the sun direction when it is at
  peak and the equator line. It is variable during
  the year, on 21 March and 21 September the sun is
  perpendicular to equator line and his value is 0
  on June and December 21 it is perpendicular to
  Cancer and Capricorn tropic and the angle is / -
  23

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The sun position

• The sun position when it is at peak changes
  during the year according to d and the latitude
  relation is 90 - (F d)
• Today february 5, the sun position on the
  horizont and the day light are
• Modena 29,5 9 50
• Kokemaki 12,3 7 42
• Beckescsaba 26,9 9 36
• Pilsen 23,8 9 18
• Recklinghausen 22 9 06
• Genk 22,6 9 12

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Calculation of each hour radiation

• The data of radiation for the whole day have been
  taken on www.solaritaly.it
• thanks to this graph we calculated the
  radiation each hour and the fraction catched by
  panel

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Panel efficiency

• The efficiency of the solar panel is the ratio
  between the energy transferred to the fluid
  vector and the catched radiation. Infact a part
  of the radiation is reflected, a part is lost due
  to the environment. Therefore the efficiency is
  variable and depends upon the external
  temperature, the radiation, and the fluid
  temperature

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Results the moving panel tansmits to the fluid
25 more energy. A family of 4 persons needs 200
kwh in one month for sanitary water. Using 2 m2
panel we are self sufficient from march to
september
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How does the system work?

• Each sensor converts a temperature in a
  proportional voltage
• solution
• tank water

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Temperature sensors
Thermocouples
Termistors
Resistance Termal Devices (RTD) Thermoresistors
Integrated sensors
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Temperature sensor LM335

• The LM35 series are precision integrated-circuit
  temperature
• sensors, whose output voltage is linearly
  proportional to the
• Celsius (Centigrade) temperature.

• LM335 used
• enviroment temperature
• heating system temperature

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How does the system work?

• PLC controls the temperature of the water using
  PID regulation

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PID

• PID regulation is a mathematic calculation that
  allows to control a process or a system, changing
  the value of a signal to achieve the set point
  value.

• This calculation uses proportional, integrative
  and derivative functions to maintain this value
  in time

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Electronic part

• The project is controlled by a PLC (programmable
  logic controller) Siemens S7-200

• This device is the brain of the system

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How does the system work?

• Actuator can be activated by the PLC to generate
  heat

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Heating system regolation

• Methods to control the heating system
• ON-OFF the actuator (the heatresistance) is
  completly off or completly on at the max power.
  This control can let oscillate the system and
  stress hardly the actuator.
• PWM (Pulse Width Modulation) it is a regulation
  technique that controls the power given to the
  actuator changing the duty cycle and not the
  frequency of the control signal.

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What we mean to do in the future

• This year
• Project pannel, boiler, pump, pipes and draw a
  P. I. scheme
• Introduce devices in our boiler
• Make the constructive drawning of the rotating
  pannel
• Next year realize the mechanical structure