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Sensitivity study to an absorption system performance considering heat and mass transfer enhancements.

Number: 2474

Author(s) : ZHENG J., CASTRO J., PAPAKOKKINOS G., OLIVA A.

Summary

This work describes the absorption system performance with working pairs LiBr−H2O and Carrol−H2O (Carrol contains LiBr and EG -Ethylene glycol- with a mass ratio at 4.5:1) considering the thermal characteristics enhancement. The enhancements affect the working pairs and components’ properties like surface tension, contact angle, minimum wetting rate (MWR), and thermal conductivity. Surfactants are employed to strengthen the Marangoni effect, hydrophilic treatment is used on the absorber to improve wettability, nanofluids of working pairs are made to increase the thermal conductivity, and mechanical vibration is also considered to enhance mass transfer. Simulations are carried out to investigate the theoretical improvements of the enhancements in the absorption system. The numerical model was implemented on a modular object−oriented simulation platform (NEST platform tool), which allows linking different components, considered objects, which can be either an empirical−based model or a more detailed CFD calculation if necessary. Besides, a simplified 2D model of the falling film is built with C++ to predict the enhancement performance with details. The data of the properties are extracted from previous experimental work or other references in terms of the enhancement characteristics. The heat and mass transfer coefficients will increase 10−30% with nanoparticles in the falling film according to the 2D model. In terms of absorption system simulations, with the nanoparticle enhancement, the thermal conductivity could increase from 5 to 50%. It could increase the working capacity of the absorption system by around 5% at the same operating condition. With the enhancement of surfactants, the working capacity could increase by around 10%, and for the vibration, the improvement is around 5%. In general, in a limited range of current thermodynamic enhancement methods, all the enhancement attribute to a higher working capacity, slightly higher COP, and COPex, while the exergy destruction almost remains the same since the energy input will barely change.

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  • Original title: Sensitivity study to an absorption system performance considering heat and mass transfer enhancements.
  • Record ID : 30030744
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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