Critical Heat Flux in Submerged Jet Impingement Boiling of Water Under Subatmospheric Conditions

Abstract

Critical heat flux (CHF) characteristics in submerged jet impingement boiling of water on a heated copper surface are investigated at subatmospheric conditions. Data are reported at a fixed surface-to-nozzle diameter ratio of 23.8 and a fixed surface-to-nozzle height of 6 nozzle diameters. Three subatmospheric pressures of 0.176 bars, 0.276 bars, and 0.477 bars are considered, corresponding to fluid saturation temperatures of 57.3 °C, 67.2 °C, and 80.2 °C and liquid-to-vapor density ratios of 8502, 5544, and 3295, respectively. At each pressure, CHF for varying jet Reynolds numbers (Re) in the range 0–14,000 are compared for two different surface finishes of roughness average values of 123 nm and 33 nm. The CHF enhancement observed with increasing Re is depicted in a nondimensional CHF map. Existing correlations available in the literature, which are out of range of the current experimental conditions, are found to poorly predict the obtained CHF data. A CHF correlation that captures the entire experimental data set within an average error of ±3% and a maximum error of ±13% is developed. The effect of fluid subcooling on submerged jet CHF is studied at the lowest pressure of 0.176 bars. Subcooled jet CHF is found to be well predicted from saturated jet CHF by using a typical subcooled pool boiling CHF correction factor.

A Generalized Critical Heat Flux Correlation for Submerged and Free Surface Jet Impingement Boiling

“…Experiments by Cardenas and Narayanan [14][15][16][17][18]. Details on the experimental facility and experiments for jet impingement boiling using subatmospheric water and FC-72 are provided else where [18].…”

“…To develop the jet impingement CHF correlation, the number of jet impingement CHF data points considered from the studies by Cardenas and Narayanan [14][15][16][17][18] is 46 (excluding pool boiling cases). Table 4 presents uncertainty estimates for measured and determined variables [23], Data reproducibility was studied by performing repetitions and replications of experiments and it was found that CHF varied between 4% and 6% [18].…”

“…[1]) were extracted using the software plot digitizer [24]. The number of jet impingement CHF data points considered from the study by Monde and Katto [1] was selected to be 30 so that roughly 60% of the total number of jet impingement CHF data points were from Cardenas and Narayanan [14][15][16][17][18] and 40% were from Monde and Katto [1], "This value was estimated from experimental procedures described in the paper and it not an actual reported quantity. The number of jet impingement CHF data points considered from the study by Monde and Katto [1] was selected to be 30 so that roughly 60% of the total number of jet impingement CHF data points were from Cardenas and Narayanan [14][15][16][17][18] and 40% were from Monde and Katto [1], "This value was estimated from experimental procedures described in the paper and it not an actual reported quantity.…”

“…Although many data points over a wide range of conditions are provided, only 30 data points were selected for a fixed jet diame ter of 2 mm and for Re up to 60,000 all at saturated conditions. Table 5 shows the range covered by the selected 30 data points used from the study by Monde and Katto [1], An additional im portant characteristic from the data set extracted from Monde and Katto [1] is that for some experimental conditions, parameters, such as fluid properties, clv Re, and CHF overlap with some exper imental condition considered by Cardenas and Narayanan [14][15][16][17][18], while others like ds fall in close proximity. Table 5 shows the range covered by the selected 30 data points used from the study by Monde and Katto [1], An additional im portant characteristic from the data set extracted from Monde and Katto [1] is that for some experimental conditions, parameters, such as fluid properties, clv Re, and CHF overlap with some exper imental condition considered by Cardenas and Narayanan [14][15][16][17][18], while others like ds fall in close proximity.…”

“…Table 1 presents a summary of 12 distinct jet impingement CHF correlations that have been proposed in literature and their respective range of parameters. The paper uses data published by this group on CHF for subatmospheric pressure submerged jet impingement boiling using de-ionized water and atmospheric pressure data using FC-72 [14][15][16][17][18]. In general, fluid properties, such as liquid and vapor densities, latent heat of vaporization, and surface tension, have always been shown to be relevant.…”