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Interfacial Phenomena and Heat Transfer
ESCI

ISSN Imprimir: 2169-2785
ISSN On-line: 2167-857X

Open Access

Interfacial Phenomena and Heat Transfer

DOI: 10.1615/InterfacPhenomHeatTransfer.2015012027
pages 325-342

TWO-PHASE FLOW AND BOILING OF R245FA IN A 1 MM PRESSING DEPTH PLATE HEAT EXCHANGER − PART I: ADIABATIC PRESSURE DROP

Farzad Vakili-Farahani
Laboratory of Heat and Mass Transfer, LTCM, Ecole Polytechnique Fédérale de Lausanne, Station 9, CH-1015 Lausanne, Switzerland; Swiss Federal Laboratories for Materials Science and Technology (Empa)
R. L. Amalfi
Laboratory of Heat and Mass Transfer, LTCM, Ecole Polytechnique Fédérale de Lausanne, Station 9, CH-1015 Lausanne, Switzerland
John R. Thome
Laboratory of Heat and Mass Transfer (LTCM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 9, CH-1015 Lausanne, Switzerland

RESUMO

This article is the first in a two-part study on two-phase flow of R245fa in a promising, new compact plate heat exchanger (PHE) design. Two extremely thin corrugated stainless steel plates (0.15 mm thick) having a pressing depth of only 1 mm and a chevron angle of 65° were assembled together to make a single-pass refrigerant flow passage, electrically heated PHE prototype for the tests. This test section was then used to investigate its mean and local thermal-hydraulic performance. In Part I, upward single-phase and two-phase adiabatic experiments were carried out to investigate total frictional pressure drops over the PHE, while in Part II the heat transfer characteristics were studied. Besides the traditional approach of measuring pressure drops with a differential transducer, a thermal (infrared) camera was used to measure the local plate surface temperatures during the two-phase adiabatic tests and thus the corresponding local pressures were indirectly obtained within the PHE. Measurements were made over a range of saturation temperatures (19 to 35°C), mass fluxes (10 to 40 kg m−2 s−1), and vapor qualities (0.05 to 0.8) to consider their influences on two-phase pressure drop within the PHE. Several of the most widely used prediction methods in the PHE literature were evaluated with respect to the present experimental databases. Then, a new prediction method was proposed capturing all the data in a range of ±30% with 11.4% MAE.