Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon

Two-phase thermosyphons, which use sodium at 960 K as a refrigerant for heat transportation in small nuclear reactors, are promising for manned exploration to Mars. This is because the concentric-tube type thermosyphon may not have a flooding limit, and so the heat transfer performance per unit volu...

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Autores principales:	Takuya HONGO, Yuki MIYACHI, Rei KIMURA, Hideki HORIE, Tomonao TAKAMATSU, Chikako IWAKI
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2020
Materias:	heat transfer flow observation thermosyphon two-phase concentric-tube Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/215d629578f045e496020298977ce495
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spelling	oai:doaj.org-article:215d629578f045e496020298977ce4952021-11-29T05:56:31ZStudy on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon2187-974510.1299/mej.19-00578https://doaj.org/article/215d629578f045e496020298977ce4952020-02-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/7/3/7_19-00578/_pdf/-char/enhttps://doaj.org/toc/2187-9745Two-phase thermosyphons, which use sodium at 960 K as a refrigerant for heat transportation in small nuclear reactors, are promising for manned exploration to Mars. This is because the concentric-tube type thermosyphon may not have a flooding limit, and so the heat transfer performance per unit volume is comparatively large. Moreover, since its external form is a single tube by inserting a pipe through which the liquid flows into a pipe through which the gas flows, the reactor core can be made smaller. Experimental investigations of heat transport characteristics using water, R113, ethanol, and nitrogen as refrigerants and development of prediction formulas are progressing for establishing the design of the concentric-tube two-phase thermosyphon. However, it is necessary to use sodium at 960 K for application to heat transportation of a reactor, and further elucidation of the flow phenomenon is necessary to establish its performance prediction model. We have proposed a model based on bubble pump theory in order to take into consideration the rise of liquid level of the heating section. We conducted an experimental study on the flow inside a thermosyphon made of transparent material, and evaluated the maximum heat transfer rate using a low boiling point refrigerant, HFE-7100. As a result, even when the heat transfer rate was close to the maximum, it was shown that the flow regime in the outer tube of the adiabatic section of the concentric tube is two-phase flow. However, the experimental value of the maximum heat transfer rate was found to be about 17 % smaller than the calculated value. We therefore investigated the cause of this difference by making pressure measurements and flow observations, and found that bubble entrainment in the inner tube of the concentric tube of the adiabatic section greatly influences the pressure distribution. It is thought that taking mixing into consideration would help improve the model.Takuya HONGOYuki MIYACHIRei KIMURAHideki HORIETomonao TAKAMATSUChikako IWAKIThe Japan Society of Mechanical Engineersarticleheat transferflow observationthermosyphontwo-phaseconcentric-tubeMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 7, Iss 3, Pp 19-00578-19-00578 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	heat transfer flow observation thermosyphon two-phase concentric-tube Mechanical engineering and machinery TJ1-1570
spellingShingle	heat transfer flow observation thermosyphon two-phase concentric-tube Mechanical engineering and machinery TJ1-1570 Takuya HONGO Yuki MIYACHI Rei KIMURA Hideki HORIE Tomonao TAKAMATSU Chikako IWAKI Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
description	Two-phase thermosyphons, which use sodium at 960 K as a refrigerant for heat transportation in small nuclear reactors, are promising for manned exploration to Mars. This is because the concentric-tube type thermosyphon may not have a flooding limit, and so the heat transfer performance per unit volume is comparatively large. Moreover, since its external form is a single tube by inserting a pipe through which the liquid flows into a pipe through which the gas flows, the reactor core can be made smaller. Experimental investigations of heat transport characteristics using water, R113, ethanol, and nitrogen as refrigerants and development of prediction formulas are progressing for establishing the design of the concentric-tube two-phase thermosyphon. However, it is necessary to use sodium at 960 K for application to heat transportation of a reactor, and further elucidation of the flow phenomenon is necessary to establish its performance prediction model. We have proposed a model based on bubble pump theory in order to take into consideration the rise of liquid level of the heating section. We conducted an experimental study on the flow inside a thermosyphon made of transparent material, and evaluated the maximum heat transfer rate using a low boiling point refrigerant, HFE-7100. As a result, even when the heat transfer rate was close to the maximum, it was shown that the flow regime in the outer tube of the adiabatic section of the concentric tube is two-phase flow. However, the experimental value of the maximum heat transfer rate was found to be about 17 % smaller than the calculated value. We therefore investigated the cause of this difference by making pressure measurements and flow observations, and found that bubble entrainment in the inner tube of the concentric tube of the adiabatic section greatly influences the pressure distribution. It is thought that taking mixing into consideration would help improve the model.
format	article
author	Takuya HONGO Yuki MIYACHI Rei KIMURA Hideki HORIE Tomonao TAKAMATSU Chikako IWAKI
author_facet	Takuya HONGO Yuki MIYACHI Rei KIMURA Hideki HORIE Tomonao TAKAMATSU Chikako IWAKI
author_sort	Takuya HONGO
title	Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
title_short	Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
title_full	Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
title_fullStr	Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
title_full_unstemmed	Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
title_sort	study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon
publisher	The Japan Society of Mechanical Engineers
publishDate	2020
url	https://doaj.org/article/215d629578f045e496020298977ce495
work_keys_str_mv	AT takuyahongo studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon AT yukimiyachi studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon AT reikimura studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon AT hidekihorie studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon AT tomonaotakamatsu studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon AT chikakoiwaki studyontheflowandheattransportcharacteristicsofconcentrictubetwophasethermosyphon
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Study on the flow and heat transport characteristics of concentric-tube two-phase thermosyphon

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