An algorithm for controlling temperature and humidity of greenhouse and aviculture


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  1. #6
    Join Date
    Aug 2006
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    Iran
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    it's not a modern system.the water pour on the pads and big fans on the other side of the saloon pull the air and flow of the air make an approximately constant temperature and humidity in aviculture. in aviculture humidity is not as important as temperature(the pads not heated) but in greenhouse we use fog makers to control humidity exactly. The fans,heaters,valves and fog makers are controlled with PIC16F877A. i put some sensors in different places of saloon and measure the humidity and temperature and send data to main controller and that controller decide what to do and it will turn on/off fans,heaters,vaves and fog makers.for example for turning on a fan, i will make PORTB.0 high and it turns on the relay(5v 10A relay) then this relay will turn on the contactor( SIEMENS 3PH contactors) and contactor with turn on the fan.i also put a keypad to control each fan and heater automatically or manually that can selected with the operator.

    imagine that we have 8 fans and 2 heaters and a valve for pour water on the pad(work as a cooler in hot weather and increase humidity)
    fans: fan1 fan2 fan3 fan4 fan5 fan6 fan7 fan8
    heaters: heater1 heater2
    valve: valve1
    fan1,fan3 fan5 and fan7 are always on for ventilation in aviculture.
    for controlling i should use fan2,fan4,fan6 and fan8 and also heaters and valve.
    so in my algorithm when i tell fans ,it means fan2,fan4,fan6 and fan8

    in aviculture humidity is not as important as temperature so i exert this margine for temperature and humidity:
    for temperature: (setpoint-1) and (setpoint+1)
    for humidity: (setpoint-4) and (setpoint+4)

    this is my algorithm that executed every 10 mintutes:


    1-if (temp<(setpoint-1)) and (humidity<(setpoint-4)) then

    turn on heaters
    turn off fans

    if the situation is not changed for 20 minutes then turn on valve

    if the situation is not changed for 40 minutes turn on alarm

    2- if (temp<(setpoint-1)) and (humidity>(setpoint+4) then

    turn off valve
    turn on heaters
    turn off fans

    if the situation is not changed for 20 minutes then turn on fans(for reducing humidity)

    if the situation is not changed for 40 minutes then turn on alarm

    3-if (temp>(setpoint+1)) and (humidity>(setpoint+4)) then

    turn off valve
    turn off heater

    if the situation is not changed for 10 minutes then turn on fans

    if the situation is not changed for 20 minutes turn on valve(for reducing temperature)

    if the situation is not changed for 40 minutes turn on on alarm


    4-if (temp>(setpoint+1)) and (humidity<(setpoint-4) then

    turn off heaters

    if the situation is not changed for 10 minutes then turn on fans and valve

    if the situation is not changed for 40 minutes then turn on alarm


    what do you think about this algorithm?
    Last edited by amindzo; - 8th November 2008 at 09:59.

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