Title: Interpreting exergy analysis as applied to spray drying systems

Authors: Perry William Johnson; Timothy A.G. Langrish

Addresses: School of Chemical Engineering, University of Sydney, Room 423, Level 4, Chemical Engineering Building J01, NSW 2006, Australia ' School of Chemical Engineering, University of Sydney, Room 423, Level 4, Chemical Engineering Building J01, NSW 2006, Australia

Abstract: The comparison of different energy recovery systems employed on a spray dryer is challenging. This work compares two cases with a base case of a dryer alone, to identify any available improvements and interpretation of the factors used within exergy analysis, for system-wide optimisation. While exergy analysis results indicate natural gas boiler systems (case 1) are superior to compressor-driven recovery systems (case 2) (13% better evaporation efficiency), this paper demonstrates the significant potential to improve either system, and that dryers are one of the limiting units within the process (38% exergy improvement potential). The improvement potential for both cases is quite high (~90% of total added exergy), particularly as the inlet gas temperature increases. This paper demonstrates a method of simplifying exergy analysis to make it more accessible to engineers as a tool for optimising thermal and non-thermal systems that include a dryer as a significant part of the system.

Keywords: energy; exergy; analysis; dryer; vapour recompression; optimisation.

DOI: 10.1504/IJEX.2020.105479

International Journal of Exergy, 2020 Vol.31 No.2, pp.120 - 149

Received: 14 Feb 2019
Accepted: 18 Aug 2019

Published online: 24 Feb 2020 *

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