Exergetic performance assessment of a long-life milk processing plant: a comprehensive survey

The aim of this study was to carry out a comprehensive exergy analysis of an industrial-scale long-life milk processing plant for the first time. The plant consisted of four main lines including steam generator, above-zero refrigeration system, milk reception, pasteurization, and standardization line, and ultra-high-temperature (UHT) milk processing unit. This survey was performed to obtain more in-depth information about the exergy destroyed in the whole plant and its main subcomponents. In addition, an attempt was made to quantify the exergy destroyed for processing a given amount of the long-life milk using the mass allocation method. The results indicated that the largest exergy destruction rate occurred in the compressor and boiler combination of the steam generation system, accounting for 89% of the total exergy destruction of the system. More specifically, the specific exergy destruction of the long-life milk processing was determined as 345.50 kJ kg−1. The steam generation system had the greatest contribution to the specific exergy destruction of the long-life milk processing followed by above-zero refrigeration system, UHT milk processing unit, and milk reception, pasteurization, and standardization line, respectively. Hence, a small improvement in the exergetic performance of the steam generator could profoundly lower the specific exergy destruction of the long-life milk processing. According to the outcomes of the current study, the performance and sustainability parameters of dairy processing plants can be best-evaluated and improved using exergy analysis.