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Theoretical analysis of absorption heat exchanger.

Number: AB-CH-1102

Author(s) : XIE X., JIANG Y.

Summary

Absorption heat exchanger (AHE) is a kind of special heat conversion device, by which heat transfer processes through two extremely unmatched fluids can be realized. There are two types of AHEs, the first type and the second type. Using the first type AHE, large temperature difference between inlet and outlet(I/O) of one fluid converted into low I/O temperature difference of another fluid, and the outlet temperature of the hot fluid with low flowrate can be lower than the inlet temperature of the cold fluid with high flowrate. Using the second type AHE, low temperature difference between inlet and outlet converted into high temperature difference, and the outlet temperature of the cold fluid with low flowrate can be higher than the inlet temperature of hot fluid with high flowrate. A temperature effectiveness has been defined for AHE s, and the temperature effectiveness of AHEs can be higher than 1, while the temperature effectiveness of common heat exchangers can only be lower than 1. The AHE is not always suitable for all heat transfer processes. Through heat transfer loss analysis, the heat transfer loss in AHEs and common heat exchangers is described by entransy loss. Moreover, the heat transfer loss is divided into two kinds of entransy loss, that is unmatched entransy loss and entransy loss caused by limited heat transfer area. Compared the entransy loss of common heat exchangers and absorption heat exchangers, the conditions to use absorption heat exchangers are obtained, which includes the large enough flow rate ratio and the
large enough proportion of unmatched entransy loss. Finally, several typical applications are given to use AHEs, including long distance transportation of low grade waste heat, fast-cooling of some chemical engineering processes, to reduce the return water temperature of primary water network in district heating system and so on.

Details

  • Original title: Theoretical analysis of absorption heat exchanger.
  • Record ID : 30022693
  • Languages: English
  • Source: International sorption heat pump conference, ISHPC 2017, Tokyo august 7-10.
  • Publication date: 2017/08/07

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