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Enhancement of R1234ze(Z) pool boiling heat transfer on horizontal titanium tubes for high-temperature heat pumps

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Title: Enhancement of R1234ze(Z) pool boiling heat transfer on horizontal titanium tubes for high-temperature heat pumps
Authors: Nagata, Ryuichi / Kondou, Chieko / Koyama, Shigeru
Issue Date: 26-May-2017
Publisher: Taylor & Francis
Citation: Science and Technology for the Built Environment, 23, pp.923-932; 2019
Abstract: R1234ze(Z), which has a global warming potential of less than 1, is a promising alternative refrigerant for hightemperature heat pumps designed for heat recovery in the industrial sector. The use of titanium as the material for heat exchangers exposed to acid exhaust is one solution to prevent oxidation. In this study, the pool boiling heat transfer characteristics outside of horizontal titanium tubes were experimentally investigated for R1234ze(Z). A plain tube and three enhanced titanium tubes were tested at saturation temperatures from 10 to 60 °C and heat fluxes from 0.55 to 79.8 kW m-2. Compared to the plain tube, the tested enhanced tube exhibited a 2.8 to 5.1 times higher heat transfer coefficient, on average, in the test range, which could compensate for the disadvantage in the thermal conductivity of titanium. The enhancement ratio predominantly depends on the saturation temperature and the wall heat flux. At conditions of higher saturation temperatures and lower heat flux, where smaller bubbles are observed, test tubes with smaller fin spaces exhibit higher heat transfer coefficients. The experimental results indicate the importance of fin geometry optimization to the operation conditions.
URI: http://hdl.handle.net/10069/39282
ISSN: 23744731
DOI: 10.1080/23744731.2017.1325706
Rights: This is an Accepted Manuscript of an article published by Taylor & Francis in Science and Technology for the Built Environment on 2017-05-26, available online: http://www.tandfonline.com/10.1080/23744731.2017.1325706
Type: Journal Article
Text Version: author
Appears in Collections:Articles in academic journal

Citable URI : http://hdl.handle.net/10069/39282

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