Thermal Analysis of a New Model of a Tobacco Dryer

Abstract

The tobacco drying greenhouses, in general, are made without any coating that ensures thermal insulation and avoid heat losses, resulting in a large consumption of firewood during the drying of the tobacco. The study aims to develop an economically viable project to the producer, to avoid excessive heat loss through the walls and ceiling of a tobacco dryer, aimed at fuel economy, reduced drying time and reduces costs in process. For the current project, we considered changes of Brazilian theoretical mode, where we developed a thermal insulation system in a dryer, reaching satisfactory results, with a large reduction in energy losses and firewood consumption, resulting in a decrease in the costs of the proceedings in general. Thus, began for the development of an ideal model of a dryer the horizontal type of 25m² of useful area, up to 2.5 tonnes of tobacco, in order to maintain the results before and/or overcome them found a constructive model to mainly benefit the producers. During the research, and analysis on the feasibility of maintaining the rock-wool as insulation materials to be used, considering his thermal and physical properties and cost/benefit as good value, economic calculations of other materials found in the market were realized, to the optimization of construction processes and reduce costs. In the structural design of concrete blocks to form walls, with their empty space filled with insulation were used. The roof was formed by double-cement tiles with rock-wool insulation inside. The furnace/ventilation group proposed was found in the market, for reasons of economic gains and constructive, with the area available for the set, designed according to the dimensions provided by the manufacturer. The main change to the existing dryer and which was taken as a basis for the work is the proposal of a thermal insulation system, linking it to an automation system of lateral openings (flaps), with the provision of temperature controllers and humidity indoors, where they are dried tobacco leaves, making these flaps open and close automatically when the humidity inside the dryer is outside the ideal, promoting greater uniformity of drying and consequent improvement in product quality. This automation means optimizing the service of the small producer, reduced energy costs and reduced fuel consumption. Theoretically, the project was efficient, concluding that with the adoption of a new constructive model with thermal insulation and automation, is viable within the current regional economic reality, with a significant reduction of energy losses and a considerable decrease in spending with firewood used in the process, therefore, with reduced environmental impact.