Abstract:
Increasing the internal temperature in tropical protected houses is a major problem for better crop growth and development. Eventhough, some remedies are in practice to control the temperature in protected houses, they are not verv effective and efficient. The research was carried out to design, develop and evaluate performance of an automated, computer operated cooling system with the ability of storing and displaying temperature data in the report form in a protected house. This system was designed to operate it electronically and the system is easy to install. An electronic sensor (LM 35) is used to measure the internal temperature of the protected house. This data is transferred to the computer via COM port by converting the data to digital signals. Data conversion and port communication was done using an electronic circuit with a microcontroller. This system could be set either manually or automatically. If the user select automatic mode, the software compares the internal temperature value with the user defined temperature value. When the internal temperature increases above the defined value, the mist system automatically starts and works until internal temperature drops below the defined value. When the system is operating manually, there are “on” or “off” buttons in the system to operate as the user wishes. To check the accuracy of the sensor used in the system, a test was conducted under the laboratory condition and it was found that there was no significant difference between the data obtained by manually and by the sensor. Under protected house condition the internal temperature of the protected house was dropped down by 2-3°C per minute with the system. Further studies are needed to control other climatological parameters such as relative humidity, light intensity etc. in protected houses.
