Infrared drying of pear slices: Drying kinetics, energy, and exergy analysis

Abstract

AbstractOver the last few decades, the drying process has proven to be a fundamental operation within the food industry, as it prolongs the shelf life and reduces the levels of deterioration of the product. Infrared drying has gained great attention in recent years as it promotes more uniform and energy‐efficient drying. Given the above, this study aimed to perform infrared drying of pear slices at different temperatures, evaluating the drying kinetics, and the thermodynamic analysis. The pear slices 3‐mm thick were dried in an infrared dryer at temperatures between 50 and 100°C until constant mass. Different mathematical models were fitted to the experimental data to represent drying as a function of time. Energy and exergy analysis were performed by applying the first and second laws of thermodynamics. The Henderson and Pabis modified model satisfactorily represented the drying of pear slices. The effective diffusion coefficient increased linearly with increasing temperature, ranging from 1.15 × 10−9 and 5.08 × 10−9 m2/s. From Arrhenius's relations, the activation energy of the drying process of pear slices was 29.87 kJ/mol. The lowest specific energy consumption (10.28 kWh/kg) was observed for higher drying temperature. The drying temperature positively influenced the energy and exergy efficiencies of the process. The efficiency of the first law of thermodynamics varied between 40 and 99%. The increase in the energy required in the dryer, overcomes the destruction of exergy in the equipment.Practical ApplicationsInfrared radiation drying is a promising high‐efficiency technology. One of the main advantages of this method is the significant reduction in drying time compared with convective drying. For a complete evaluation of the drying system, analysis of the first and second laws of thermodynamics must be applied. Few studies on energy and exergy analysis of infrared dryers are found. A detailed literature review showed that there is no information on energy and exergy analysis of the infrared drying process of pear slices. It is believed that this study will contribute to the pear food industry by providing results from the best drying process in terms of kinetics, energy, and exergy.