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Dynamic modelling and optimization of energy storage density for sorption thermal battery.

Number: 0407

Author(s) : CHOI H. W., JEONG J., KANG Y. T.

Summary

This paper deals with the dynamic characteristics of the thermophysical equilibrium between the vapor and the solution in the sorption thermal battery. We expand the precedent quasi-steady modelling of the sorption thermal battery using water-lithium bromide to the unsteady dynamic model to compare the heat transfer rate of the heat exchanger and to validate the vapor mass is relevant to the performance characteristics of the sorption thermal battery. The existing quasi-steady modelling ignores the mass and heat capacity of the vapor regime and assumes the vapor reaches instantaneous thermodynamic equilibrium with the solution. However, the vapor dynamics is separately computed in dynamic modelling to clarify the validity of the assumption by comparing the required time to reach the thermal equilibrium between the vapor and the solution in the dynamic modelling with a time step of quasi-steady modelling. Also, the dynamic model considers the vapor dynamics with distributed UA of the heat exchanger so that it can distinguish the subcooled solution region from the saturated region. The difference as much as 10.49% in the amount of the heat exchange of the generator is confirmed due to the vapor pressure difference. The NTU of the generator employed for quasi-steady model should be estimated 33.5% higher than that of the dynamic modelling to match the solution properties of both models continuously. It means the NTU of the generator is underestimated in quasi-steady modelling, which causes critical error in determining the heat transfer rate of heat exchanger. The compensated NTU is used to investigate the optimized performance point. The final energy storage density is 434.94 kJ/kg and COP is 0.75 at the optimized point.

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Pages: 9 p.

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Details

  • Original title: Dynamic modelling and optimization of energy storage density for sorption thermal battery.
  • Record ID : 30031604
  • Languages: English
  • Subject: Technology
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0407

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