Integrated performance assessment of vacuum heat pump drying: a multi-criteria framework for energy-quality optimization in banana slice drying

Abstract

The industry faces significant challenges from growing demands for energy-efficient food processing while maintaining exceptional product quality has created significant challenges for the industry. An integrated performance assessment framework for vacuum heat pump drying (VHPD) systems was developed in this study, combining thermodynamic analysis with comprehensive quality evaluation through multi-criteria optimization. Banana slices were dried using a laboratory-scale VHPD system at temperatures ranging from 40–60 °C and vacuum pressures of 0–80 kPa. Six thin-layer drying models were evaluated, with the Page model exhibiting superior predictive performance (R² = 0.9964, RMSE = 0.0150). Effective moisture diffusivity was found to range from 1.15 × 10⁻¹⁰ to 1.98 × 10⁻¹⁰ m² s⁻¹, with activation energies between 16.47–19.60 kJ mol⁻¹. A novel Integrated Performance Index (IPI) was constructed incorporating a specific moisture extraction rate, exergy efficiency, color retention, and vitamin C preservation using multi-criteria decision analysis. Optimal conditions (60 °C, 80 kPa) were identified, achieving an IPI of 0.796 while balancing efficiency (SMER = 0.179 kg water per kWh, exergy efficiency = 0.524) with quality retention (vitamin C = 46.6%). Response surface analysis was subsequently employed to identify robust optimization regions for practical implementation. This framework represents the first comprehensive approach unifying energy, exergy, and quality parameters within a single decision-support tool for sustainable food processing.