8) TEMPERATURE CONTROL
The temperature range for plant growth
is narrow, i.e., from about 10 °C to 30 °C. High temperature increases growth rates
but reduces yields, while low temperature tends to increase yields but slow
down growth rates. However, the relationship between plant growth and
temperature is complex because it is a function of various metabolic processes.
So an “optimum” temperature will vary with different objectives. The accuracy
of temperature measurement is not only decided by sensor itself, but also
influenced by the manner in which the measurement is made. Radiation,
conduction, and convection can change the heat transfer on the equilibrium
temperature of a temperature sensor.
Following the rules to minimize uncertainty
in the resulting temperature measurement are the first one is any temperature
sensor must be radiation shielded and aspirated. Then, the sensor must be
located properly to the plant (e.g., plant surface temperature or plant air
space temperature). After that, data must be accumulated with regard to the
change (time constant). The last one is the properties of the sensor should be
known, such as accuracy and response time.
9) COMPARISON BETWEEN EXISTING PRODUCT
1) DEVELOPMENT
OF HUMIDITY CONTROL & AUTOMATIC GREENHOUSE WATERING SYSTEM.
The Development of Humidity Control & Automatic
Greenhouse Watering System features such as artificial light when there is
insufficient natural light. The temperature condition is set, controlled and
maintained, according to user’s desired value. The humidity condition fixed according to
greenhouse condition.
2) GREENHOUSE
CONTROL SYSTEM
This
project has being built by Student University of Illinois. The features of this
project are user need to operate device by manually. The greenhouse control
system can control temperature only. The temperature range on this greenhouse
control system between 15ºC to 35 ºC.
3) GREENHOUSE
TEMPERATURE & HUMIDITY CONTROL SYSTEM
This
project has been built by Korea facility management. Due to the fragile nature
of growing plants within a greenhouse, this project had requirements for the
implementation of their automated system, which is the temperature and humidity
of the greenhouse be recorded and allow automatic adjustments. The system
allows remote monitoring and control through the Internet. In the current of a
failure, either on the controller or auxiliary equipment, the controller will
send an alarm signal to the administrative. All the equipment that used in the
system is highly in terms of product cost and maintenance.
