Heat Transfer and Critical Heat Flux of Subcooled Water Flow Boiling in a SUS304-Tube With Twisted-Tape Insert

2010 ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Effective Length ◽  
Twisted Tape ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfers

The subcooled boiling heat transfer (HT) and the steady-state critical heat fluxes (CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G = 4016 to 13950 kg/m2s), inlet liquid temperatures (Tin = 285.82 to 363.96 K), outlet pressures (Pout = 764.76 to 889.02 kPa) and exponentially increasing heat input (Q = Q0 exp(t/τ), τ = 8.5 s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d = 6 mm), heated length (L = 59.5 mm), effective length (Leff = 49.1 mm), L/d (= 9.92), Leff/d (= 8.18) and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.89 μm) is used in this work. The SUS304 twisted tape with twist ratios, y [= H/d = (pitch of 180° rotation)/d], of 2.39, 3.39 and 4.45 are used. The relations between inner surface temperatures and heat fluxes for the SUS304-tubes with various twisted-tape inserts are clarified from non-boiling to CHF. The subcooled boiling heat transfers for SUS304-tubes with various twisted-tape inserts are compared with our empty SUS304-tube data and the values calculated by our and other workers’ correlations for the subcooled boiling heat transfer. The influences of the twisted-tape insert, the twist ratio and the swirl velocity on the subcooled boiling heat transfer and the CHFs are investigated into details and the widely and precisely predictable correlations of the subcooled boiling heat transfer and the CHFs for turbulent flow of water in the SUS304-tubes with twisted-tape inserts are given based on the experimental data. The correlations can describe the subcooled boiling heat transfer coefficients and the CHFs obtained in this work within −25 to +15% difference.

Heat Transfer and Critical Heat Flux of Subcooled Water Flow Boiling in a SUS304-Tube With Twisted-Tape Insert

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Effective Length ◽  
Twisted Tape ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfers

The subcooled boiling heat transfer and the steady state critical heat fluxes (CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G=4016–13,950 kg/m2 s), inlet liquid temperatures (Tin=285.8–364.0 K), outlet pressures (Pout=764.8–889.0 kPa), and exponentially increasing heat input (Q=Q0 exp(t/τ) and τ=8.5 s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d=6 mm), heated length (L=59.5 mm), effective length (Leff=49.1 mm), L/d(=9.92), Leff/d(=8.18), and wall thickness (δ=0.5 mm) with average surface roughness (Ra=3.89 μm) is used in this work. The SUS304 twisted-tape with twist ratios y[=H/d=(pitch of 180 deg rotation)/d] of 2.39, 3.39, and 4.45 are used. The relations between inner surface temperatures and heat fluxes for the SUS304-tubes with various twisted-tape inserts are explored for different flow regimes ranging from single-phase flows to CHF. The subcooled boiling heat transfers for SUS304-tubes with various twisted-tape inserts are compared with authors’ empty SUS304-tube data and the values calculated by authors’ and other workers’ correlations for the subcooled boiling heat transfer. The influences of the twisted-tape insert, the twist ratio, and the swirl velocity on the subcooled boiling heat transfer and the CHFs are investigated into details, and the correlations of the subcooled boiling heat transfer and the CHFs for turbulent flow of water in the SUS304-tubes with twisted-tape inserts are given based on the experimental data. The precision or accuracy of a more widely set of correlations in predicting the present set of data is evaluated. The correlations can describe the subcooled boiling heat transfer coefficients and the CHFs obtained in this work from −25% to +15% difference.

Subcooled Water Flow Boiling Heat Transfer in a Short SUS304-Tube With Twisted-Tape Insert

2010 ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Effective Length ◽  
Twisted Tape ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The subcooled boiling heat transfer (HT) and the steady-state critical heat fluxes (CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G = 4016 to 13850 kg/m2s), inlet liquid temperatures (Tin = 285.82 to 363.96 K), outlet pressures (Pout = 764.76 to 889.02 kPa) and exponentially increasing heat input (Q = Q0exp(t/τ), τ = 8.5 s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d = 6 mm), heated length (L = 59.5 mm), effective length (Leff = 49.1 mm), L/d (= 9.92), Leff/d (= 8.18) and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.18 μm) is used in this work. The SUS304 twisted tape with twist ratio, y [= H/d = (pitch of 180° rotation)/d], of 3.39 is used. The relation between inner surface temperature and heat flux for the SUS304-tube with the twisted-tape insert are clarified from non-boiling to CHF. The subcooled boiling heat transfer for SUS304-tube with the twisted-tape insert is compared with our empty SUS304-tube data and the values calculated by our and other workers’ correlations for the subcooled boiling heat transfer. The influences of the twisted-tape insert and the swirl velocity on the subcooled boiling heat transfer and the CHFs are investigated into details and the widely and precisely predictable correlations of the subcooled boiling heat transfer and the CHFs for turbulent flow of water in the SUS304-tube with twisted-tape insert are given based on the experimental data. The correlations can describe the subcooled boiling heat transfer coefficients and the CHFs obtained in this work within −25 to +15% difference.

Subcooled Water Flow Boiling Heat Transfer in a Short SUS304-Tube With Twisted-Tape Insert

2010 ◽  
Vol 133 (5) ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Effective Length ◽  
Twisted Tape ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The subcooled boiling heat transfer and the steady-state critical heat fluxes (CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G=4016–13,850 kg/m2 s), inlet liquid temperatures (Tin=285.82–363.96 K), outlet pressures (Pout=764.76–889.02 kPa), and exponentially increasing heat input (Q=Q0 exp(t/τ), τ=8.5 s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d=6 mm), heated length (L=59.5 mm), effective length (Leff=49.1 mm), L/d(=9.92), Leff/d(=8.18), and wall thickness (δ=0.5 mm) with average surface roughness (Ra=3.18 μm) is used in this work. The SUS304 twisted tape with twist ratio, y(=H/d=(pitch of 180 deg rotation)/d), of 3.39 is used. The relation between inner surface temperature and heat flux for the SUS304-tube with the twisted-tape insert are clarified from nonboiling to CHF. The subcooled boiling heat transfer for SUS304-tube with the twisted-tape insert is compared with our empty SUS304-tube data and the values calculated by our and other workers’ correlations for the subcooled boiling heat transfer. The influences of the twisted-tape insert and the swirl velocity on the subcooled boiling heat transfer and the CHFs are investigated into details and the widely and precisely predictable correlations of the subcooled boiling heat transfer and the CHFs for turbulent flow of water in the SUS304-tube with twisted-tape insert are given based on the experimental data. The correlations can describe the subcooled boiling heat transfer coefficients and the CHFs obtained in this work within −25 to +15% difference.

Subcooled Boiling Heat Transfer in a Short Vertical SUS304-Tube at High Liquid Reynolds Number

2009 ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Spontaneous Nucleation

The subcooled boiling heat transfer and the steady state critical heat fluxes (CHFs) in a short vertical SUS304-tube for the flow velocities (u = 17.28 to 40.20 m/s), the inlet liquid temperatures (Tin = 293.30 to 362.49 K), the inlet pressures (Pin = 842.90 to 1467.93 kPa) and the exponentially increasing heat input (Q = Q0 exp(t/τ), τ = 10 s) were systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tubes of inner diameters (d = 3 and 6 mm), heated lengths (L = 33 and 59.5 mm), effective lengths (Leff = 23.3 and 49.1 mm), L/d (= 11 and 9.92), Leff/d (= 7.77 and 8.18), and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.18 μm) are used in this work. The inner surface temperature and the heat flux from non-boiling to CHF were clarified. The subcooled boiling heat transfer for SUS304 test tube was compared with our Platinum test tube data and the values calculated by other workers’ correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details and the widely and precisely predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical SUS304-tube is given based on the experimental data. The correlation can describe the subcooled boiling heat transfer coefficients obtained in this work within 15% difference. Nucleate boiling surface superheats for the SUS304 test tube become very high. Those at the high liquid Reynolds number are close to the lower limit of Heterogeneous Spontaneous Nucleation Temperature. The dominant mechanisms of the flow boiling CHF in a short vertical SUS304-tube are discussed.

Subcooled Boiling Heat Transfer for Turbulent Flow of Water in a Short Vertical Tube

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Koichi Hata ◽  
Suguru Masuzaki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbulent Flow ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Vertical Tube ◽  
Test Tube ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Infrared Thermal Imaging

The subcooled boiling heat transfer and the critical heat flux (CHF) due to exponentially increasing heat inputs with various periods (Q=Q0 exp(t/τ), τ=22.52 ms–26.31 s) were systematically measured by an experimental water loop flow and observed by an infrared thermal imaging camera. Measurements were made on a 3 mm inner diameter, a 66.5 mm heated length, and a 0.5 mm thickness of platinum test tube, which was divided into three sections (upper, mid, and lower positions). The axial variations of the inner surface temperature, the heat flux, and the heat transfer coefficient from nonboiling to critical heat flux were clarified. The results were compared with other correlations for the subcooled boiling heat transfer and authors’ transient CHF correlations. The influence of exponential period (τ) and flow velocity on the subcooled boiling heat transfer and the CHF was investigated and the predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical tube was derived based on the experimental data. In this work, the correlation gave 15% difference for subcooled boiling heat transfer coefficients. Most of the CHF data (101 points) were within 15% and −30 to +20% differences of the authors’ transient CHF correlations against inlet and outlet subcoolings, respectively.

Transient Critical Heat Fluxes of Subcooled Water Flow Boiling in a Short SUS304-Tube With Twisted-Tape Insert

2012 ◽  
Author(s):  
Koichi Hata ◽  
Yasuyuki Shirai ◽  
Suguru Masuzaki
Keyword(s):  
Steady State ◽  
Flow Boiling ◽  
Test Tube ◽  
Heat Fluxes ◽  
Effective Length ◽  
Twisted Tape ◽  
Swirl Velocity ◽  
Twist Ratio ◽  
Inner Diameter ◽  
Heated Length

The transient critical heat fluxes (transient CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G = 3997.79 to 13419.8 kg/m2s), inlet liquid temperatures (Tin = 293.55 to 300.85 K), outlet pressures (Pout = 825.19 to 860.95 kPa) and exponentially increasing heat inputs (Q = Q0exp(t/τ), τ = 26.85 ms to 8.42 s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d = 6 mm), heated length (L = 59.4 mm), effective length (Leff = 49.4 mm), L/d (= 9.9), Leff/d (= 8.23) and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.89 μm) is used in this work. The SUS304 twisted-tape with width (w = 5.6 mm), thickness (δT = 0.6 mm), total length (l = 372 mm) and twist ratio, y [= H/d = (pitch of 180° rotation)/d], of 3.37 is used. The transient CHFs for a short SUS304-tube with twisted-tape insert are compared with authors’ steady-state CHF data for a short SUS304-tube with various twisted-tape inserts, their transient CHF data for the empty SUS304-tube and the values calculated by authors’ steady-state CHF correlations for the test tubes with various twisted-tape inserts and their transient CHF correlations for the empty test tubes. The influences of twisted-tape insert, heating rate and swirl velocity on the transient CHF are investigated into details and the widely and precisely predictable correlations of the transient CHF for the test tube with twisted-tape insert are given based on the experimental data. The correlations can describe the transient CHFs for a short SUS304-tube with twisted-tape of y = 3.37 obtained in this work within −27 to 7.9 % difference.

Surface Roughness Effects on Flow Boiling in Microchannels

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
Benjamin J. Jones ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Pressure Drop ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Boiling Heat Transfer ◽  
Cut Surface

The influence of surface roughness on flow boiling heat transfer and pressure drop in microchannels is experimentally explored. The microchannel heat sink employed in the study consists of ten parallel, 25.4 mm long channels with nominal dimensions of 500×500 μm2. The channels were produced by saw-cutting. Two of the test piece surfaces were roughened to varying degrees with electrical discharge machining (EDM). The roughness average Ra varied from 1.4 μm for the as-fabricated, saw-cut surface to 3.9 μm and 6.7 μm for the two roughened EDM surfaces. Deionized water was used as the working fluid. The experiments indicate that the surface roughness has little influence on boiling incipience and only a minor impact on saturated boiling heat transfer coefficients at lower heat fluxes. For wall heat fluxes above 1500 kW/m2, the two EDM surfaces (3.9 μm and 6.7 μm) have similar heat transfer coefficients that were 20–35% higher than those measured for the saw-cut surface (1.4 μm). A modified Bertsch et al. [2009, “A Composite Heat Transfer Correlation for Saturated Flow Boiling in Small Channels,” Int. J. Heat Mass Transfer, 52, pp. 2110–2118] correlation was found to provide acceptable predictions of the flow boiling heat transfer coefficient over the range of conditions tested. Analysis of the pressure drop measurements indicates that only the roughest surface (6.7 μm) has an adverse effect on the two-phase pressure drop.

Subcooled Boiling Heat Transfer for Turbulent Flow of Water in a Short Vertical Tube

2008 ◽  
Author(s):  
Koichi Hata ◽  
Nobuaki Noda
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Surface Temperature ◽  
Boiling Heat Transfer ◽  
Vertical Tube ◽  
Test Tube ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Average Roughness ◽  
Inner Surface

The subcooled boiling heat transfer for Platinum test tube divided into three sections (upper, mid and lower positions) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet liquid temperatures (Tin = 295.26 to 305.25 K), the inlet pressures (Pin = 739.26 to 1064.48 kPa) and the exponentially increasing heat input with various periods (Q = Q0 exp(t/τ), τ = 22.52 ms to 26.31 s) was systematically measured by an experimental water loop comprised of a pressurizer. The Platinum test tube of inner diameter (d = 3 mm), heated length (L = 66.5 mm), L/d (= 22.17) and wall thickness (δ = 0.5 mm) with a commercial finish of inner surface (average roughness, Ra = 0.40 μm) is used in this work. The outer surface temperature of the test tube was observed by an infrared thermal imaging camera. The axial variations of the inner surface temperature, the heat flux and the heat transfer coefficient from non-boiling to CHF were clarified. The subcooled boiling heat transfer for Platinum test tube with a commercial finish of inner surface was compared with the values calculated by other workers’ correlations for the subcooled boiling heat transfer. The influence of exponential period (τ) and flow velocity (u) on the subcooled boiling heat transfer is investigated into details and the predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical tube is derived based on the experimental data for Platinum test tube with a commercial finish of inner surface. The correlation can describe the subcooled boiling heat transfer coefficients obtained in this work within 15% difference.

Experimental Study of Flow Boiling Heat Transfer in Mini-Tube

2005 ◽  
Author(s):  
Lihong Wang ◽  
Min Chen ◽  
Manfred Groll
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Boiling Heat Transfer

Flow boiling heat transfer characteristics of R134a were experimentally investigated in a horizontal stainless steel mini-tube. The inner diameter of the test tube is 1.3 mm and the tube wall thickness is 0.1 mm. Local heat transfer coefficients are obtained over a range of vapor qualities up to 0.8, mass fluxes from 310 to 860 kg/m2s, heat fluxes from 21 to 50 kW/m2, and saturation pressures from 6.5 to 7.5 bar. The mass flux, heat flux, saturation pressure, and vapor quality dependences of heat transfer coefficients are demonstrated. Based on an available model in recent literature potential heat transfer mechanisms are also analyzed.

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