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Thermodynamic analysis of single and double-effect absorption refrigeration systems for cooling ethanol fermentation process.

Number: pap. n. 42

Author(s) : ARAÚJO H. V. de, ANGELO J. V. H. d'

Summary

Alcoholic fermentation, one of the most important stages for industrial ethanol production from sugar cane, is an exothermic process. Sometimes cooling towers are not capable of supplying a cold utility with a temperature low enough to maintain the fermentative medium temperature in a desirable range. In this sense, Absorption Refrigeration Systems (ARS) appears to be a good alternative to obtain the necessary refrigeration for the fermentation process. The aim of the present paper was to carry out a thermodynamic analysis of ARS, evaluating their performance through the First and Second Laws of Thermodynamics. ARS with different configurations were studied (single-effect and double-effect with series, parallel and reverse parallel flows), all of them operating with water/lithium bromide (H2O/LiBr) mixture as working pair, under various operating conditions seeking to satisfy the cooling load required by an industrial alcoholic fermentation process. Additionally, another objective of this paper was to investigate the risk of LiBr crystallization, which can result in scaling, with the aid of the solid-liquid phase equilibrium curve of H2O/LiBr mixture. Among the double-effect configurations studied, it was observed that the one with series flow presents the more significant crystallization risk, which represents a limit to improve its First and Second Law performances. In this way, the double-effect with parallel and reverse parallel flows are more advantageous in comparison with the series flow. It was verified that the Second Law performance of the single and double-effect ARS studied are similar, but the First Law performance of these systems are considerably different because of the amount and quality of heat consumed in the first effect generators of these systems. For a base case studied, First Law performance measured by COP of double-effect ARS is 72% greater than the one for singleeffect, while for the Second Law performance, measured by exergetic efficiency, it is 5% greater.

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Details

  • Original title: Thermodynamic analysis of single and double-effect absorption refrigeration systems for cooling ethanol fermentation process.
  • Record ID : 30014319
  • Languages: English
  • Source: International sorption heat pump conference (ISHPC2014), College Park, United States, March 31-April 2, 2014.
  • Publication date: 2014/03/02

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