Automation of monitoring of drying parameters in hybrid solar-electric dryer for agricultural products

ABSTRACT Increasing the efficiency of solar dryers with ensuring that the system remains accessible to all users can be achieved with their automation through low-cost and easy-to-use technique sensors. The objective was to develop, implement and evaluate an automatic system for monitoring drying parameters in a hybrid solar-electric dryer (HSED). Initially, an automated data acquisition system for collecting the parameters of sample mass, air temperature, and relative air humidity was developed and installed. The automatic mass data acquisition system was calibrated in the hybrid solar-electric dryer. The automated system was validated by comparing it with conventional devices for measuring the parameters under study. The data obtained were subjected to analysis of variance, Tukey test and linear regression at p ≤ 0.05. The system to turn on/off the exhaust worked efficiently, helping to reduce the errors related to the mass measurement. The GERAR Mobile App showed easy to be used since it has intuitive icons and compatibility with the most used operating systems for mobile devices. The responses in communication via Bluetooth were fast. The use of Arduino, a low-cost microcontroller, to automate the monitoring activity allowed estimating the mass of the product and collecting the drying air temperature and relative air humidity data through the DHT22. This sensor showed a good correlation of mass and air temperature readings between the automatic and conventional system, but low correlation for relative air humidity. In general, the automatic data acquisition system monitored in real time the parameters for drying agricultural products in the HSED. RESUMO O aumento da eficiência de secadores solares com garantia de que o sistema permaneça acessível a todos os usuários pode ser alcançado com sua automação por meio de sensores de baixo custo e fácil utilização. Objetivou-se desenvolver, implantar e avaliar um sistema automático de monitoramento dos parâmetros de secagem em secador híbrido solar-elétrico (SHSE). Inicialmente, foi desenvolvido e instalado o sistema automático de aquisição de dados para a coleta dos parâmetros de massa da amostra e temperatura do ar e umidade relativa do ar de secagem. O sistema automatizado foi validado comparando-o com aparelhos convencionais de medição dos parâmetros em estudo. Os dados obtidos foram submetidos à análise de variância, teste de Tukey e regressão linear a p ≤ 0,05. O sistema ligar/desligar do exaustor funcio