Modeling a hybrid solar- gas dehydrating plant for agro-industrial products

Abstract

The article presents the development of a mathematical model for a dehydrating plant with a processing capacity of 100 to 200 kg of fresh product with both solar and gas thermal sources. The comprehensive plant model is based on mass and energy balances that consider the impact of real environmental conditions into the process. The model reproduces an experimental pineapple dehydration process with a maximum relative error of 7 %. According to our simulation results, reducing infiltration rate into the drying tunnel from 20 % to 0 % leads to a 7 °C increase in air drying temperature. This represents a reduction in drying time of 24 min. A 30 min reduction in drying time was observed when the drying airflow was decreased by 50 %. While increasing the airflow by 70 % results in 10 min longer drying time. When the minimum drying air temperature was increased from 40 °C to 70 °C, the drying time was reduced by 90 min. This reduces the use of electrical energy but increases the use of gas. Therefore, we estimated a energy total cost of $12.20 per 100 kg batch. Given the limited number of hybrid plant models in the literature, the integral dynamic modeling strategy offers an interesting option due to its flexibility, as it can be extended to the analysis of different plants and products. Furthermore, it enables the potential establishment of design, operation, and control strategies that could result in the process intensification.