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A tuned model to optimize a water-ammonia heat transformer.

Number: AB-SS-1039

Author(s) : GARONE S., TOPPI T., APRILE M., et al.

Summary

Based on recently obtained experimental data, a thermodynamic model for a water-ammonia heat transformer is developed. To conform the model to the real behaviour of the prototype, we called into question a few commonly used assumptions and replaced them with empirical correlations. The result is a tuned model effectively able to give an accurate picture of all cycle variables. Such a model is used to analyse the cycle behaviour, allowing to understand how distribution issues affect the real machine. Due to the high vapour quality at restrictor outlet, some solution is dragged into the refrigerant flow. Thus, refrigerant concentration and therefore performances are slightly lower than expected. To optimize the operation, we used the model to assess the impact of two possible solutions: an additional heat exchanger to increase the sub-cooling at restrictor inlet and the replacement of the falling film generator with a plate heat exchanger. The additional heat exchanger can halve the vapour quality while increasing the required generator’s capacity. The falling film heat exchanger, if actually able to cope with a strongly two-phase flow at its entrance, is expected to solve the distribution issues and increase the prototype good performances.

Details

  • Original title: A tuned model to optimize a water-ammonia heat transformer.
  • Record ID : 30022727
  • Languages: English
  • Source: International sorption heat pump conference, ISHPC 2017, Tokyo august 7-10.
  • Publication date: 2017/08/07

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