Visualization of two-phase flow of R410A in horizontal smooth and axial micro-finned tubes

Cheng Min Yang; Pega Hrnjak

doi:10.1016/j.ijheatmasstransfer.2019.03.174

Visualization of two-phase flow of R410A in horizontal smooth and axial micro-finned tubes

Cheng Min Yang, Pega Hrnjak

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

This paper presents a novel visualization approach to understand the effect of axial micro-fins on two-phase flow behavior inside horizontal round tubes. In order to reflect the real inner geometry in the commercial metal tubes (smooth and micro-finned tubes), clear resin tubes were made by an SLA 3D printer to reproduce the geometry. The 3D printed tube for visualization was installed right after the heat transfer test section. In the heat transfer test section, R410A flow boiling experiments were conducted at 10 °C saturation temperature with heat flux of 15 kW/m². The results indicated the axial micro-fins do not provide additional force to lift up the liquid in the round tube and the annular flow pattern does not occur earlier (at lower vapor quality or mass flux conditions) than the smooth tube. For low mass flux and vapor quality, the liquid-phase refrigerant is easily trapped in the grooves at the top or side of the axial micro-finned tube. The main liquid level in the axial micro-finned tube is, therefore, lower than that in the smooth tube under the same conditions. This liquid level change is quantified by tracing the liquid-vapor interfaces in the captured videos with change point analysis.

Original language	English
Pages (from-to)	49-58
Number of pages	10
Journal	International Journal of Heat and Mass Transfer
Volume	138
DOIs	https://doi.org/10.1016/j.ijheatmasstransfer.2019.03.174
State	Published - Aug 2019
Externally published	Yes

Funding

This study is supported by the Air-Conditioning and Refrigeration Center (ACRC) at the University of Illinois at Urbana-Champaign (UIUC). The authors would like to acknowledge the technical support from Creative Thermal Solutions Inc. (CTS). The authors are also grateful to MechSE RP Lab at UIUC for manufacturing 3D-printed tubes.

Funders	Funder number
Air-Conditioning and Refrigeration Center
University of Illinois at Urbana-Champaign

Keywords

3D printed
Axial micro-fin
Change point analysis
Flow boiling
Flow visualization
Transparent micro-finned tube

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10.1016/j.ijheatmasstransfer.2019.03.174

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title = "Visualization of two-phase flow of R410A in horizontal smooth and axial micro-finned tubes",

abstract = "This paper presents a novel visualization approach to understand the effect of axial micro-fins on two-phase flow behavior inside horizontal round tubes. In order to reflect the real inner geometry in the commercial metal tubes (smooth and micro-finned tubes), clear resin tubes were made by an SLA 3D printer to reproduce the geometry. The 3D printed tube for visualization was installed right after the heat transfer test section. In the heat transfer test section, R410A flow boiling experiments were conducted at 10 °C saturation temperature with heat flux of 15 kW/m2. The results indicated the axial micro-fins do not provide additional force to lift up the liquid in the round tube and the annular flow pattern does not occur earlier (at lower vapor quality or mass flux conditions) than the smooth tube. For low mass flux and vapor quality, the liquid-phase refrigerant is easily trapped in the grooves at the top or side of the axial micro-finned tube. The main liquid level in the axial micro-finned tube is, therefore, lower than that in the smooth tube under the same conditions. This liquid level change is quantified by tracing the liquid-vapor interfaces in the captured videos with change point analysis.",

keywords = "3D printed, Axial micro-fin, Change point analysis, Flow boiling, Flow visualization, Transparent micro-finned tube",

author = "Yang, {Cheng Min} and Pega Hrnjak",

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AB - This paper presents a novel visualization approach to understand the effect of axial micro-fins on two-phase flow behavior inside horizontal round tubes. In order to reflect the real inner geometry in the commercial metal tubes (smooth and micro-finned tubes), clear resin tubes were made by an SLA 3D printer to reproduce the geometry. The 3D printed tube for visualization was installed right after the heat transfer test section. In the heat transfer test section, R410A flow boiling experiments were conducted at 10 °C saturation temperature with heat flux of 15 kW/m2. The results indicated the axial micro-fins do not provide additional force to lift up the liquid in the round tube and the annular flow pattern does not occur earlier (at lower vapor quality or mass flux conditions) than the smooth tube. For low mass flux and vapor quality, the liquid-phase refrigerant is easily trapped in the grooves at the top or side of the axial micro-finned tube. The main liquid level in the axial micro-finned tube is, therefore, lower than that in the smooth tube under the same conditions. This liquid level change is quantified by tracing the liquid-vapor interfaces in the captured videos with change point analysis.

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Visualization of two-phase flow of R410A in horizontal smooth and axial micro-finned tubes

Abstract

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Keywords

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