Corresponding States Correlations for Pool and Flow Boiling Burnout

1985 ◽  
Vol 107 (2) ◽  
pp. 392-397 ◽  
Author(s):  
A. Sharan ◽  
J. H. Lienhard ◽  
R. Kaul
Keyword(s):  
Heat Flux ◽  
Dipole Moment ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Probable Error ◽  
Universal Functions ◽  
Acentric Factor ◽  
Peak Heat Flux ◽  
The Common ◽  
System Geometry

The peak pool boiling heat flux can be nondimensionalized so the dimensionless peak heat flux is a function of a Bond or Laplace number that characterizes the system geometry. The dimensionless peak heat flux can be interpreted as the product of a geometrical function (given by previous investigations), universal functions of the reduced saturation pressure, and the Pitzer acentric factor. The latter universal functions are constructed by correlation. These are combined to give a single prediction of the peak heat flux that applies to all the common geometrical heater configurations. The probable error of the prediction, when it is compared with the available peak heat flux data, is 6.1 percent for substances whose dipole moment is not high. The method is also extended to create a comparable correlation for flow boiling burnout during crossflows over cylinders. There is a lack of data with which to check this correlation fully.

Flow Pattern, Heat Transfer and Pressure Drop Behaviors of Micro-Channel Flow Boiling

2018 ◽  
Author(s):  
Sira Saisorn ◽  
Pochai Srithumkhant ◽  
Pakorn Wongpromma ◽  
Maturose Suchatawat ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Flow Boiling ◽  
Flow Direction ◽  
Saturation Pressure ◽  
Nucleate Boiling ◽  
Steel Tube ◽  
Stainless Steel Tube

Two-phase flow of R-134a with high confinement number was experimentally carried out in this study. Flow boiling conditions for different orientations were controlled to take place in a stainless steel tube having a diameter of 0.5 mm. Based on a saturation pressure of 8 bar, a heat flux range of 2–26 kW/m2, and a mass flux range of 610–815 kg/m2s, a constant surface heat flux condition was controlled by applied DC power supply on the test section. The flow behaviors were described based on flow pattern and pressure drop data while heat transfer mechanisms were explained by using heat transfer coefficient data. In this work, nucleate boiling was observed, and the importance of the change in the flow direction was neglected, corresponding to the confinement number of around 1.7.

The Effect of Inlet Orifice on Critical Heat Flux and Flow Boiling Heat Transfer in Single Horizontal Microtube

2013 ◽  
Author(s):  
Yanfeng Fan ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Working Fluid ◽  
Flow Boiling Heat Transfer

Flow oscillation is a crucial issue for the development of flow boiling heat transfer in the applications. Inlet orifice has been proven be an option to eliminate the oscillation. However, the effects of inlet orifice on critical heat flux and flow boiling heat transfer coefficient are lack of study. In this work, the effects of inlet restriction on critical heat flux and heat transfer coefficient in single horizontal microtube under uniform heating condition is experimentally investigated using FC-72 as working fluid. A stainless steel microtube with an inner diameter of 889 μm is selected as main microtube. Two smaller microtubes are assembled at the inlet of main microtube to achieve the restriction configurations of 50% and 20% area ratios. The experimental measurement is carried out at mass fluxes ranging from 160–870 kg/m2·s and heat fluxes varying from 6–170 kW/m2. Two saturation pressures, 10 and 45 kPa, are tested. The experimental results of critical heat flux and two phase heat transfer coefficient obtained in the microtube without orifice are compared with the existing correlations. The addition of an orifice does not enhance the normal critical heat flux but increases the premature critical heat flux. In aspect of heat transfer, the orifice shows improvement on heat transfer coefficient at low mass flux and high saturation pressure.

scholarly journals Experimental Investigation on Flow Boiling Heat Transfer and Pressure Drop of a Low-GWP Refrigerant R1234ze(E) in a Horizontal Minichannel

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5972
Author(s):  
Yu Xu ◽  
Zihao Yan ◽  
Ling Li
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Experimental Investigation ◽  
Pressure Drop ◽  
Mass Flux ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Nucleate Boiling ◽  
Vapor Quality ◽  
Frictional Pressure Drop

To protect the environment, a new low-GWP refrigerant R1234ze(E) was created to substitute R134a. However, its flow boiling performances have not received sufficient attention so far, which hinders its popularization to some extent. In view of this, an experimental investigation was carried out in a 1.88 mm horizontal circular minichannel. The saturation pressures were maintained at 0.6 and 0.7 MPa, accompanied by mass flux within 540–870 kg/m2 s and heat flux within 25–65 kW/m2. For nucleate boiling, a larger heat flux brings about a larger heat transfer coefficient (HTC), while for convective boiling, the mass flux and vapor quality appear to take the lead role. The threshold vapor quality of different heat transfer mechanisms is around 0.4. Additionally, larger saturation pressure results in large HTC. As for the frictional pressure drop (FPD), it is positively influenced by mass flux and vapor quality, while negatively affected by saturation pressure, and the influence of heat flux is negligible. Furthermore, with the measured data, several existing correlations are compared. The results indicate that the correlations of Saitoh et al. (2007) and Müller-Steinhagen and Heck (1986) perform best on flow boiling HTC and FPD with mean absolute deviations of 5.4% and 10.9%.

Flow Film Boiling From a Sphere to Subcooled Freon-11

1986 ◽  
Vol 108 (4) ◽  
pp. 934-938 ◽  
Author(s):  
J. A. Orozco ◽  
L. C. Witte
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Velocity ◽  
Flow Boiling ◽  
Empirical Correlation ◽  
The Other ◽  
Film Boiling ◽  
Vapor Film ◽  
Peak Heat Flux ◽  
Semi Empirical

The boiling curves for flow boiling of freon-11 from a fluid-heated 3.81-cm-dia copper sphere showed dual maxima. One maximum corresponded to the nucleate peak heat flux while the other was caused by transitory behavior of the wake behind the sphere. Film boiling data were predicted well by the theory of Witte and Orozco. A semi-empirical correlation of the film boiling data accounting for both liquid velocity and subcooling predicted the heat transfer to within +/− 20 percent. The conditions at which the vapor film became unstable were also determined for various sub-coolings and velocities.

Considerations in Predicting Burnout of Cylinders in Flow Boiling

1992 ◽  
Vol 114 (1) ◽  
pp. 185-193 ◽  
Author(s):  
P. Sadasivan ◽  
J. H. Lienhard
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Flow Boiling ◽  
Heater Surface ◽  
Near Surface ◽  
Surface Temperature Distribution ◽  
Peak Heat Flux ◽  
Far Wake ◽  
Gravity Surface

Previous investigations of the critical heat flux in flow boiling have resulted in widely different hydrodynamic mechanisms for the occurrence of burnout. Results of the present study indicate that existing models are not completely realistic representations of the process. The present study sorts out the influences of the far-wake bubble breakoff and vapor sheet characteristics, gravity, surface wettability, and heater surface temperature distribution on the peak heat flux in flow boiling on cylindrical heaters. The results indicate that burnout is dictated by near-surface effects. The controlling factor appears to be the vapor escape pattern close to the heater surface. It is also shown that a deficiency of liquid at the downstream end of the heater surface is not the cause of burnout.

Flow Boiling of R134a in Circular Microtubes—Part II: Study of Critical Heat Flux Condition

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Saptarshi Basu ◽  
Sidy Ndao ◽  
Gregory J. Michna ◽  
Yoav Peles ◽  
Michael K. Jensen
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Heat Flux ◽  
Flow Pattern ◽  
Flow Regime ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Absolute Error ◽  
Two Phase

A detailed experimental study was carried out on the critical heat flux (CHF) condition for flow boiling of R134a in single circular microtubes. The test sections had inner diameters (ID) of 0.50 mm, 0.96 mm, and 1.60 mm. Experiments were conducted over a large range of mass flux, inlet subcooling, saturation pressure, and vapor quality. CHF occurred under saturated conditions at high qualities and increased with increasing mass fluxes, tube diameters, and inlet subcoolings. CHF generally, but not always, decreases with increasing saturation pressures and vapor qualities. The experimental data were mapped to the flow pattern maps developed by Hasan [2005, “Two-Phase Flow Regime Transitions in Microchannels: A Comparative Experimental Study,” Nanoscale Microscale Thermophys. Eng., 9, pp. 165–182] and Revellin and Thome [2007, “A New Type of Diabatic Flow Pattern Map for Boiling Heat Transfer in Microchannels,” J. Micromech. Microeng., 17, pp. 788–796]. Based on these maps, CHF mainly occurred in the annular flow regime in the larger tubes. The flow pattern for the 0.50 mm ID tube was not conclusively identified. Four correlations—the Bowring correlation, the Katto-Ohno correlation, the Thome correlation, and the Zhang correlation—were used to predict the experimental data. The correlations predicted the correct experimental trend, but the mean absolute error (MAE) was high (>15%) A new correlation was developed to fit the experimental data with a MAE of 10%.

scholarly journals Experimental Study on the Flow Boiling Heat Transfer Characteristics in a Mini-Channel with Offset Fins

Proceedings ◽  
2018 ◽  
Vol 2 (22) ◽  
pp. 1376
Author(s):  
Tao Wen ◽  
Hongbo Zhan ◽  
Yimo Luo ◽  
Dalin Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Rectangular Channels ◽  
Flow Boiling Heat Transfer

The present study studied the flow boiling heat transfer performance of a mini channel with offset fins experimentally. The hydraulic diameter for it is 1.59 mm with 9 offset rectangular channels. The influences of saturation pressure, mass flux and heat flux on heat transfer coefficient were investigated. The experimental results reveal that when the vapor quality of refrigerant is less than 0.6, the mass flux has negligible influence on heat transfer coefficient. While it increases with both the saturation pressure and heat flux. Differently, in the high quality region, the heat transfer coefficient has an ascending trend with the increase of mass flux and is not affected by heat flux and saturation pressure.

Heat Transfer Characteristics of Flow Boiling of R134a in Uniformly Heated Horizontal Circular Microtubes

2010 ◽  
Author(s):  
Saptarshi Basu ◽  
Sidy Ndao ◽  
Gregory J. Michna ◽  
Yoav Peles ◽  
Michael K. Jensen
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Mass Flux ◽  
Flow Boiling ◽  
Saturation Pressure ◽  
Nucleate Boiling ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

An experimental study of two-phase heat transfer coefficients was carried out using R134a in uniformly heated horizontal circular microtubes with diameters of 0.50 mm and 1.60 mm. The effects of mass flux, heat flux, saturation pressure, and vapor quality on heat transfer coefficients were studied. The flow parameters investigated were as follows: exit pressures of 490, 670, 890, and 1160 kPa; mass fluxes of 300–1500 kg/m2s; heat fluxes of 0–350 kW/m2; inlet subcooling of 5, 20, and 40 °C; and exit qualities of 0 to 1.0. The parametric trends presented in the study are consistent with published literature. Heat transfer coefficients increased with increasing heat flux and saturation pressure while they were independent of variations in mass flux. Vapor quality had a negligible influence on heat transfer coefficients. For the conditions studied, the trends indicated that the dominant heat transfer mechanism was nucleate boiling. The experimental data was compared to three microchannel correlations — the Lazarek-Black, the Kandlikar, and the Tran Correlations. None of the correlations predicted the experimental data very well, although they all predicted the correct trend within limits of experimental error.

A Thermo-Hydraulic Investigation of the Unprecedented TMRS Upper Neutron Spallation Target

2021 ◽  
pp. 1-35
Author(s):  
Matthew Scheel ◽  
Keith Woloshun ◽  
Eric Olivas
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Local Heat Transfer ◽  
Flow Loop ◽  
Spallation Target ◽  
Target Station ◽  
Peak Heat Flux

Abstract The next-generation neutron spallation target station, the Target-Moderator-Reflector System (TMRS) Mk. IV, will be installed in 2021. This iteration features an unprecedented, water-cooled, third internal target aptly named the Upper Target. With the Upper Target designed completely by analysis, a complementary empirical investigation was undertaken to ascertain target conformance to those computational results which deemed the cooling efficacious. Three facets of the target were designated for verification: displacement under hydraulic load, critical fluid velocities, and the characteristic heat transfer coefficient. With the potential for flow maldistribution under excessive displacements, static pressure testing was performed. Discrepancies of an order of magnitude became evident between empirical and simulated displacements, 1.499 mm vs. 0.203 mm, respectively. A closed water flow loop reproducing the flow parameters intrinsic to the TMRS Mk. IV was constructed. Utilizing particle image velocimetry, global fluid dynamics were observed to be analogous to computer simulation. Furthermore, crucial velocities such as those at the point of beam impingement were met or exceeded, thus satisfying cooling requirements by preponderance. A graphite susceptor mirroring nominal beam geometry was coupled to a solenoid coil to replicate a prodigious peak heat flux of 169 W/cm2 via induction heating. Matching peak heat flux within 3% engendered a heat transfer coefficient 80% that of simulation. Consistent with analysis, the local heat transfer coefficient sufficiently mitigated nucleate/flow boiling. In summary, the analytically-derived Upper Target design empirically demonstrated sufficient cooling despite quixotic beam conditions and unforeseen displacements.

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