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Experimental comparison of the heat transfer performance of R134a and R1234ze(E) in a hybrid film evaporator.

Number: pap. n. 1431

Author(s) : CENSI G., GIANCOTTI L., PADOVAN A.

Summary

Environmental and cost issues in vapour compression systems call for new high efficiency evaporators with reduced refrigerant charge. This paper presents a new concept of shell-and-tube heat exchanger, named hybrid film evaporator. In this, a liquid film falls down from the top to the bottom and it is re-distributed on each row of tubes by means of special drilled plates. The heat transfer mechanism is a combination of falling film evaporation and pool boiling. When compared to a flooded evaporator, the refrigerant charge is significantly lower, almost 40% for the entire chiller, while maintaining the same heat transfer capacity and overall dimensions. The experimental heat transfer performances of a hybrid film evaporator prototype, working with R134a and R1234ze(E), are presented and discussed. The results show that nucleate boiling is not the only heat transfer mechanism and, at the same heat flux, the measured heat transfer coefficient of R1234ze(E) is even 20% lower than that of R134a.

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Details

  • Original title: Experimental comparison of the heat transfer performance of R134a and R1234ze(E) in a hybrid film evaporator.
  • Record ID : 30026755
  • Languages: English
  • Source: Proceedings of the 25th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.
  • Publication date: 2019/08/24
  • DOI: http://dx.doi.org/10.18462/iir.icr.2019.1431
  • Notes:

    Keynote


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