DESIGN OF A MICROCONTROLLER BASED TEMPERATURE-HUMIDITY CONTROL SYSTEM OF BIO-MASS FIRED TOBBACCO CURING BARNS FOR SMALL TO MEDIUM SCALE FARMERS IN ZIMBABWE

Abstract

High quality cured tobacco is one of the most foreign currency generators in Zimbabwe. Currently curing process within the small to medium scale farmers is through curer’s experience. In order to reduce this dependency and achieve high quality the curing process requires a well-designed temperature control system. A biomass fired flue curing tobacco barn design for small-medium scale farmers in Zimbabwe with a clear objective to control temperature and humidity is the focal point of this paper. The designed barn accommodates capacity of small-medium tobacco farmers with a provision to use firewood, coal or dung in as source of energy. To reduce curer experience dependency a furnace with seized fuel trays, which are charged into the furnace as per calculated frequency for every curing stage basing on heat content and type of fuel was incorporated. The designed barn system that, have an outside control box contains a combination of heat extraction fans, cold air blowers and humidifiers that regulate temperatures and humidity levels to required levels for every curing stage under the instruction from 16F887 microcontroller. This has replaced the primitive way to check thermometers inside the barn even at high temperatures of about 80°C. Commendable energy efficiency was realized in various system performance simulations through different techniques