Critical heat flux (CHF) for water flow in tubes—I. Compilation and assessment of world CHF data

Hall, David D.; Mudawar, Issam

doi:10.1016/s0017-9310(99)00191-x

Cited by 127 publications

(28 citation statements)

References 31 publications

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“…As described also in Hall and Mudawar [16], the validation of this detection method was confirmed by increasing the heat flux over the limit of 110 • C. It was found that irrevocable dryout and actual damage of the heater occurred at heat fluxes only a few percent higher than that ascribed to be CHF by the current method. Thus, the measured values are expected to be within a few percent of the real CHF values, which represents incurring only a small error to save the test section from burnout.…”

Section: Flow Boiling Curvessupporting

confidence: 69%

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Critical heat flux in multi-microchannel copper elements with low pressure refrigerants

Park

Thome

2010

International Journal of Heat and Mass Transfer

107

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Section: Flow Boiling Curvessupporting

confidence: 69%

“…Hall and Mudawar [16] and Zhang et al [47]); however, most of the work has been aimed at macro scale systems, such as for nuclear power plants. Accordingly, a great portion of these studies employed a single macroscale circular tube.…”

Section: State Of the Art Of Critical Heat Flux In Microchannelsmentioning

confidence: 99%

Critical heat flux in multi-microchannel copper elements with low pressure refrigerants

Park

Thome

2010

International Journal of Heat and Mass Transfer

107

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“…The critical heat flux (CHF) represents the upper limit to the cooling capacity of two-phase technologies and is an important consideration in the system design. Although CHF for conventional flow boiling has been extensively studied [2], CHF data for boiling heat transfer in microchannels are still scarce, especially for boiling in heat sinks with multiple parallel microchannels.…”

Section: Introductionmentioning

confidence: 99%

A Study of Critical Heat Flux During Flow Boiling in Microchannel Heat Sinks

Chen

Garimella

2011

ASME/JSME 2011 8th Thermal Engineering Joint Conference

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The cooling capacity of two-phase transport in microchannels is limited by the occurrence of critical heat flux (CHF). Due to the nature of the phenomenon, it is challenging to obtain reliable CHF data without causing damage to the device under test. In this work, the critical heat fluxes for flow boiling of FC-77 in a silicon thermal test die containing 60 parallel microchannels were measured at five total flow rates through the microchannels in the range of 20–80 ml/min. CHF is caused by dryout at the wall near the exit of the microchannels, which in turn is attributed to the flow reversal upstream of the microchannels. The bubbles pushed back into the inlet plenum agglomerate; the resulting flow blockage is a likely cause for the occurrence of CHF which is marked by an abrupt increase in wall temperature near the exit and an abrupt decrease in pressure drop across the microchannels. A database of 49 data points obtained from five experiments in four independent studies with water, R-113, and FC-77 as coolants was compiled and analyzed. It is found that the CHF has a strong dependence on the coolant, the flow rate, and the area upon which the flux definition is based. However, at a given flow rate, the critical heat input (total heat transfer rate to the coolant when CHF occurs) depends only on the coolant and has minimal dependence on the details of the microchannel heat sink (channel size, number of channels, substrate material, and base area). The critical heat input for flow boiling in multiple parallel microchannels follows a well-defined trend with the product of mass flow rate and latent heat of vaporization. A power-law correlation is proposed which offers a simple, yet accurate method for predicting the CHF. The thermodynamic exit quality at CHF is also analyzed and discussed to provide insights into the CHF phenomenon in a heat sink containing multiple parallel microchannels.

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“…Although CHF has been extensively studied for flow boiling in large channels, as summarized by Hall and Mudawar [6], CHF data for boiling heat transfer in microchannels are still scarce. A study of CHF for water in tubes of diameters of 0.3 to 2.7 mm was conducted by Vandervort et al [7] under the following conditions: mass fluxes of 5000 to 40000 kg/m²-s, exit subcoolings of 40 to 135°C, length-to-diameter ratios of 2 to 50, and exit pressure of 0.2 to 2.2 MPa.…”

Section: Introductionmentioning

confidence: 99%

Flow Boiling Heat Transfer to a Dielectric Coolant in a Microchannel Heat Sink

Chen

Garimella

2005

Advances in Electronic Packaging, Parts A, B, and C

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This paper presents an experimental study of flow boiling heat transfer in a microchannel heat sink. The dielectric fluid Fluorinert FC-77 is used as the boiling liquid after it is fully degassed. The experiments were performed at three flow rates ranging from 30 to 50 ml/min. The heat transfer coefficients, as well as the critical heat flux, were found to increase with flow rate. Wall temperature measurements at three locations (near the inlet, near the exit, and in the middle of heat sink) reveal that wall dryout first occurs near the exit of the microchannels. The ratio of heat transfer rate under critical heat flux conditions to the limiting evaporation rate was found to decrease with increasing flow rate, asymptotically approaching unity. Predictions from a number of correlations for nucleate boiling heat transfer in the literature are compared against the experimental results to identify those that provide a good match. The results of this work provide guidelines for the thermal design of microchannel heat sinks in two-phase flow.

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Critical heat flux (CHF) for water flow in tubes—I. Compilation and assessment of world CHF data

Cited by 127 publications

References 31 publications

Critical heat flux in multi-microchannel copper elements with low pressure refrigerants

Critical heat flux in multi-microchannel copper elements with low pressure refrigerants

A Study of Critical Heat Flux During Flow Boiling in Microchannel Heat Sinks

Flow Boiling Heat Transfer to a Dielectric Coolant in a Microchannel Heat Sink

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