Numerical modeling of a hybrid greenhouse solar dryer with single-pass solar air heater for bitter gourd flakes drying: a finite element analysis

The objective of this study was to develop a finite element model that explains the drying performance of a hybrid greenhouse dryer equipped with a single-pass solar air heater for drying of bitter gourd flakes. The model utilized the finite element method (FEM) to solve a set of partial differential equations (PDEs) that describe the combined heat and mass transfer process during drying. The 3-dimensional finite element model provided a visual representation of the spatial distribution of moisture within the bitter gourd sample. The mesh used in the model consisted of Lagrange triangle finite elements with small sizes and second-order geometry shapes. A time-dependent analysis was performed to capture changes in moisture content during the 5-hour of drying. The model predicted maximum crop and ground temperatures of 60.10°C and 77.20°C, respectively, with a drying efficiency of 42.91%. The relative humidity inside the drying chamber was 30.4%. The energy and exergy efficiencies were determined to be 80.09% and 53.83%, respectively. The predicted results were validated against experimental data and it was found that the hybrid greenhouse solar dryer, with moderate inside temperatures, is a suitable option for bitter gourd flakes drying while maintaining environmental sustainability. Graphical abstract