A comprehensive assessment of energetic and exergetic performance for the dehumidification system of a processed pistachio production unit
Authors: Dowlati Majid , Golpour Iman , Blanco‐Marigorta Ana M. , Marcos J. Daniel , de la Guardia Miguel , Sheikhshoaei Hasan 
Published: October 2023

The present study aims to conduct a comprehensive evaluation of the energetic and exergetic performance of a dehumidification system utilized in the processing of raw pistachios. The assessment involved the application of the first and second laws of thermodynamics to calculate the exergy aspects of each component of the system, including input and output exergy rates, output/input exergy efficiency, product/fuel exergy efficiency, exergy destruction rate, exergy loss rate, exergy improvement potential rate, and specific exergy consumption. Furthermore, the effect of variations in reference state temperature on the exergy parameters was also investigated. The results indicated that the pre‐dryer chamber had the highest input exergy rate among all the components of the dehumidification system. The product/fuel exergy efficiency is specified to be 35.10%, 9.47%, and 60.43%, for the electro‐fan, heater, and pre‐dryer chamber, respectively, while their output/input exergy efficiency are 87.87%, 22.10%, and 56.28%, respectively. The values of the exergy destruction rate of these components are 0.83, 147.14, and 1.12 kW whereas the exergy loss rate values are found to be 0.03, 4.12, and 9.24 kW, respectively. The improvement potential rate values of these components are obtained to be 0.10, 117.83, and 4.53 kW, while the amount of specific exergy consumption for the dehumidification system is determined as 481.85 kJ/kg. The study also reveals that the exergy parameters vary with changes in reference state temperature and that the exergy efficiencies decrease linearly as reference state temperature rises. Therefore, the findings of this investigation demonstrate the potential for using exergy analysis as an effective tool to improve the performance of dehumidification systems in industrial settings, specifically in the production of pistachios.

Practical applications

Pistachio nut known as green gold because of its high economical value, is one of the popular nuts over the world. Dehumidification system based on drying technology could be used in food industry with many distinct advantages for processing of particulate crops like pistachios. For a comprehensive assessment of this system, analysis of the first and second laws of thermodynamics is applied. Exergy aspect based on the thermodynamic analysis the is an important stage for designing, modeling, optimizing, and performance assessment of the dehumidification system to produce processed pistachio. The results of this study show that the performance of dehumidification system could be improved by incorporating a steam compressor, a secondary heat exchanger, self‐heat recuperation technology, and a pinch method. It is believed that such a study would contribute to the industrial exploitation of pistachio which can provide insight into decreasing energy consumption and reducing capital costs for engineers and factory owners.