Development of an environmental control system for a mushroom house

Study was conducted on an experimental mushroom farm to understand the problems of temperature and humidity maintenance inside the house. Temperature condition was found both lower and higher than the optimum while higher value of relative humidity was dominant most of the time. The temperature and humidity layering in vertical plane was causing non uniform inside environment of the house. A control system was designed and developed for maintaining the optimum conditions of the temperature and humidity in the mushroom house. Emphasis was given on the simplicity and low cost. Steam was selected as a source for both heat and humidity while water spray and hot air as a source of humidity and heat alone, respectively. Ventilation was used as a means for removing excess heat and humidity from the house. A blower was used to circulate the inside air to overcome the layering problem. A controller was designed to communicate between these remedy actions and the house environment. Appropriate action was being taken by the controller on the basis of the instantaneous conditions of the parameters inside the house. Selected sensors were used to sense the instantaneous conditions of these parameters while the desired conditions were set by the potentiometers. Comparators were used to decide the status of the parameters with respect to the desired one and suitable configuration of logical gates were used for making appropriate choice among the various remedy actions present to suit the momentary condition. Remedy actions were controlled through relay or a combination of relay and solenoid value. User are allowed to set the maximum and minimum limit of the optimum range for both temperature and humidity. The controller does not take any action in optimum case. The designed control system can assist the farmers in maintaining the required environmental conditions inside a mushroom house.