Energy and exergy evaluation in a densified biomass burner using cocoa shells, intended for air heating for the artificial drying of food

Abstract

Residual biomass as a renewable resource provides alternatives for energy generation, turning a problem into an opportunity for the industry. This study aims to analyze the energy and exergy performance of a biomass burner that uses cocoa shells as fuel for air heating and subsequent artificial drying of food. The study involves a conventional exergy analysis evaluating the energy performance of the equipment and proposing improvements to enhance the thermal efficiency of the system. The research consists of six phases: it begins with defining the input data of the system, followed by determining the thermodynamic properties of the working fluid (air), the exergies of the biofuel and the working fluid are calculated, energy and exergy balances are performed in the heat exchanger of the burner, and efficiencies are obtained. Finally, a sensitivity analysis is conducted to understand the burner’s behavior under different scenarios. The results showed an average exergy efficiency of 9.8%. By increasing energy efficiency in the sensitivity analysis, the outlet temperature rises to 164°C; however, exergy destruction decreases by 48.7%. One of the significant conclusions of this study proposes modifying the coil design to improve the exergy efficiency of the system due to its heat transfer capacity to the air.