CFD Simulations and Experimental Verification on Nucleate Pool Boiling of Liquid Nitrogen XIONG Wei K. Tang, Chen Jianye, Wang Yuchen, Zhang Xiaobin* Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou, 310027, China Supported by National High-Tech Research & Development Program of China (863 Program) (SS2013AA050503) Stories of Boiling Nucleate boiling is a useful and common way of heat transfer in mechanical industry. Bubbles generated, merged, and coalesced in the nucleate boiling region, leading to a complicated temperature and pressure field distribution. Experiments using cryogenic fluids are much more intricate and complicated than experiments conducted with common fluids. The UMich and NASA have already conducted profound boiling researches on [1] LH2 & LN2 in 1970 .They have formulated boiling curves under various boiling combinations. But they recorded no photographs or micro bubble analysis. [1] Merte H, Laboratory. U O M H. Incipient and steady boiling of liquid nitrogen and liquid hydrogen under reduced gravity[EB/OL]. Heat Transfer Laboratory, University of Michigan, 1970. State-of-the-art CORRELATIONS Mostly applied to water, organic fluids, and some [1] common fluids only ； Researches concerning cryogenic fluids such as 3 He ，H2，and N2 lack enough experimental comparisons and verifications, accuracy can’t be guaranteed； Researches on nucleate boiling of liquid nitrogen mainly focused on flow boiling in micro-tube. It still remains blank in researches on bubble departure frequency and diameter. [1] Carey V P. Liquid-vapor phase-change phenomena : an introduction to the thermophysics of vaporization and condensation processes in heat transfer equipment[M]. Washington, D.C.: State-of-the-art CORRELATIONS Contributors Correlations 𝑓= Cole 4𝑔 𝜌𝑙 − 𝜌𝑔 3𝐷𝑏 𝜌𝑙 Zuber 0.59 𝜎𝑔 𝜌𝑙 − 𝜌𝑔 𝑓= 𝐷𝑏 𝜌𝑙 2 Kocamustafaogullari and Ishii 1.18 𝜎𝑔 𝜌𝑙 − 𝜌𝑔 𝑓= 𝐷𝑏 𝜌𝑙 2 𝑓= Hatton and Hall 𝑓 = 0.9 Ivey 𝑓 = 0.44 𝑔 𝐷𝑏 3 𝜋𝜂𝑙 0.5 0.25 0.25 16𝑘𝑙 𝜎𝑇𝑠𝑎𝑡 ℎ𝑓𝑔 𝜌𝑔 2 2 𝐷𝑏 𝐷𝑐 0.5 𝑔 𝐷𝑏3 for hydrodynamic region 0.25 for transition region Mostly applied to water, organic fluids, and some 𝐶 [1] 𝑓 = for thermodynamic region common fluids only 𝐷； Researches concerning cryogenic fluids such as 0.5 3 1 𝑔 4𝜎 He ，H2，and N2 lack enough experimental 𝑓= 1+ 2 𝜋 accuracy 2𝐷𝑏 𝐷𝑏 𝜌𝑔 𝑔 can’t comparisons and verifications, Stephan be guaranteed； Researches on nucleate boiling of liquid nitrogen mainly focused on flow boiling in micro-tube. It still remains blank in researches on bubble departure frequency and diameter. 2 𝑏 [1] Carey V P. Liquid-vapor phase-change phenomena : an introduction to the thermophysics of vaporization and condensation processes in heat transfer equipment[M]. Washington, D.C.: State-of-the-art CORRELATIONS Contributors Correlations 𝐷𝑏 𝐷𝑏𝐹 = 0.0208𝜑 Fritz 6𝜎 Zuber 𝐷𝑏 = Han and Griffith 𝐷𝑏 = 0.843𝜑 𝑔 𝜌𝑙 − 𝜌𝑔 𝐷𝑏 = Cole and Shulman 𝐷𝑏 = 𝜑 Cole Cole and Rohsenow Tolubinskiy and Kostanchuk 𝑘∆𝑇𝑠𝑢𝑝 𝑄𝑤 1/3 2𝜎 0.5 𝑔 𝜌𝑙 − 𝜌𝑔 0.5 𝜎 𝑃−1 𝑔 𝜌𝑙 − 𝜌𝑔 0.5 𝜎 𝑔 𝜌𝑙 − 𝜌𝑔 𝐷𝑏 = 1.5 × 10−4 0.5 𝜎 𝑔 𝜌𝑙 − 𝜌𝑔 𝜌𝑙 𝐶𝑝,𝑙 ∆𝑇𝑠𝑢𝑝 𝜌𝑔 ℎ𝑓𝑔 0.5 𝜎 𝜌𝑙 𝐶𝑝,𝑙 𝑇𝑠𝑎𝑡 𝜌𝑔 ℎ𝑓𝑔 𝑔 𝜌𝑙 − 𝜌𝑔 𝐷𝑏 = 𝐷𝑟𝑒𝑓 exp − ∆𝑇𝑠𝑢𝑏 ∆𝑇𝑟𝑒𝑓𝑑 𝑎= Ünal 𝐷𝑏 = 1.25 𝑄𝑤 − ℎ𝑙 ∆𝑇𝑠𝑢𝑏 𝐶= 2.42 × 10−5 𝑃0.709 𝑎 1 3𝑘 𝑙 2𝐶 1 3 ℎ𝑓𝑔 𝜋𝑘𝑙 𝜌𝑙 𝐶𝑝,𝑙 𝜌𝑔 ℎ𝑓𝑔 𝜇𝑙 𝐶𝑝,𝑙 𝜎 𝑘𝑤 𝜌𝑤 𝐶𝑝,𝑤 , 𝑘𝑙 𝜌𝑙 𝐶𝑝,𝑙 0.013ℎ𝑓𝑔 𝑃𝑟1.7 𝜌𝑙 − 𝜌𝑔 𝑔 0.5 3 , 𝑏𝜙 𝑏 = ∆𝑇𝑠𝑢𝑏 2 1 − 𝜌𝑔 𝜌𝑙 , Mostly applied to water, organic fluids, and some [1] common fluids only ； Researches concerning cryogenic fluids such as 3 He ，H2，and N2 lack enough experimental Kocamustafaogullari comparisons and verifications, accuracy can’t and Ishii be guaranteed； Lee, et alResearches on nucleate boiling of liquid nitrogen mainly focused on flow boiling in micro-tube. It Kim still remains blank in researches on bubble departure frequency and diameter. 𝜙= 𝐷𝑏 = 0.0012 𝜌𝑙−𝜌𝑔 0.9 Dd = 8437.5 ρl − ρv σ 𝜌𝑙 𝑢𝑙 0.61 1.0 0.47 𝑓𝑜𝑟 𝑢𝑙 ≥ 0.61 𝑚 𝑠 𝑓𝑜𝑟 𝑢𝑙 < 0.61 𝑚 𝑠 𝐷𝑏𝐹 α2l ρl 2 Ja σ Dd = 0.1649Ja0.7 [1] Carey V P. Liquid-vapor phase-change phenomena : an introduction to the thermophysics of vaporization and condensation processes in heat transfer equipment[M]. Washington, D.C.: State-of-the-art CORRELATIONS Contributors Cornwel and Brown Lemmert and Chawla Koncar et al. Kurul and Podowski Krepper et al. Correlations 𝑚 𝑁𝑎 ~𝑇𝑠𝑢𝑝 𝑁𝑎 = 𝑛∆𝑇𝑠𝑢𝑝 𝑁𝑎 = 𝑛 ∆𝑇𝑠𝑢𝑝 ∆𝑇𝑟𝑒𝑓𝑁 m = 4.5 𝑚 n = 185 , m = 1.805 n = 210 , m = 1.805 n = 0.8 × 106, ΔTrefN =10 K 𝑚 (Bartolomej et al. [31]) n = 3 × 107 (DEBORA 1-2 [33]) n = 5 × 106 (DEBORA 3-7 [33]) Kirichenko 𝑁𝑎 = 𝑛 𝜌𝑔 ℎ𝑓𝑔 ∆𝑇𝑠𝑢𝑝 𝜎𝑇𝑠𝑎𝑡 𝑚 n = 1 × 10−7 , m = 2, 𝑃/𝑃𝑐𝑟 ≥ 0.04 n = 6.25 × 10−6 , m = 3, 𝑃/𝑃𝑐𝑟 < 0.04 Mostly applied to water, organic fluids, and some [1] common fluids only ； Researches concerning cryogenic fluids such as 3 He ，H2，and N2 lack enough experimental comparisons and verifications, accuracy can’t be guaranteed； Researches on nucleate boiling of liquid nitrogen mainly focused on flow boiling in micro-tube. It still remains blank in researches on bubble departure frequency and diameter. [1] Carey V P. Liquid-vapor phase-change phenomena : an introduction to the thermophysics of vaporization and condensation processes in heat transfer equipment[M]. Washington, D.C.: State-of-the-art CORRELATIONS Contributors Cornwel and Brown Lemmert and Chawla Koncar et al. Kurul and Podowski Krepper et al. Correlations 𝑚 𝑁𝑎 ~𝑇𝑠𝑢𝑝 𝑁𝑎 = 𝑛∆𝑇𝑠𝑢𝑝 𝑁𝑎 = 𝑛 ∆𝑇𝑠𝑢𝑝 ∆𝑇𝑟𝑒𝑓𝑁 m = 4.5 𝑚 n = 185 , m = 1.805 n = 210 , m = 1.805 n = 0.8 × 106, ΔTrefN =10 K 𝑚 (Bartolomej et al. [31]) n = 3 × 107 (DEBORA 1-2 [33]) n = 5 × 106 (DEBORA 3-7 [33]) Kirichenko 𝑁𝑎 = 𝑛 𝜌𝑔 ℎ𝑓𝑔 ∆𝑇𝑠𝑢𝑝 𝜎𝑇𝑠𝑎𝑡 𝑚 n = 1 × 10−7 , m = 2, 𝑃/𝑃𝑐𝑟 ≥ 0.04 n = 6.25 × 10−6 , m = 3, 𝑃/𝑃𝑐𝑟 < 0.04 Mostly applied to water, organic fluids, and some common fluids only[1]; Researches concerning cryogenic fluids such as He3, H2, and N2 lack enough experimental comparisons and accuracy can’torganic be guaranteed; verifications, Mostly applied to water, fluids, and some [1] Researches common fluids on nucleate only ； boiling of LN2 mainly focused onResearches concerning cryogenic fluids such asin flow boiling in micro tube. It still remains blank 3 He ，H2，and N2 lack enough experimental researches on and bubble departure frequency diameter. comparisons verifications, accuracy and can’t be guaranteed； Researches on nucleate boiling of liquid nitrogen mainly focused on flow boiling in micro-tube. It still remains blank in researches on bubble departure frequency and diameter. [1] Carey V P. Liquid-vapor phase-change phenomena : an introduction to the thermophysics of vaporization and condensation processes in heat transfer equipment[M]. Washington, D.C.: Experimental Setup Experimental Setup 4 thermocouples are set in the cone, another thermocouple measures the temperature of liquid nitrogen. Using Keithley 2700 and HSC to acquire the measured data. The 4 points are expected to follow a linear pattern, from which we could derive the wall temperature. Experimental Setup 4 thermocouples are set in the cone, another thermocouple measures the temperature of liquid nitrogen. Using Keithley 2700 and HSC to acquire the measured data. The 4 points are expected to follow a linear pattern, from which we could derive the wall temperature. Video Clip From Experiment What’s about this magic? Experimental Phenomena [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena 𝒒 < 𝒒𝑳𝑯𝑭 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena 𝒒𝑳𝑯𝑭 < 𝒒 < 𝒒𝑭𝑫𝑵𝑩 Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 2nd Stage: Difficult to define the exact diameter. Bubbles followed a random pattern neither discretely nor as bubble stems. 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena Fully Developed Nucleate Boiling 𝒒𝑳𝑯𝑭 < 𝒒 < 𝒒𝑭𝑫𝑵𝑩 Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 2nd Stage: Difficult to define the exact diameter. Bubbles followed a random pattern neither discretely nor as bubble stems. 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena 𝒒𝑭𝑫𝑵𝑩 < 𝒒 < 𝒒𝑪𝑯𝑭 Fully Developed Nucleate Boiling 𝒒𝑳𝑯𝑭 < 𝒒 < 𝒒𝑭𝑫𝑵𝑩 Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 3rd Stage: The merged bubble is a unity-Bubble Stem. 𝒇 = 𝟏𝟑. 𝟒𝟕𝒔−𝟏 [11 ,the merged bubble stem is treated as one bulk. 2nd Stage: Difficult to define the exact diameter. Bubbles followed a random pattern neither discretely nor as bubble stems. 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena Critical Heat Flux 𝒒𝑭𝑫𝑵𝑩 < 𝒒 < 𝒒𝑪𝑯𝑭 Fully Developed Nucleate Boiling 𝒒𝑳𝑯𝑭 < 𝒒 < 𝒒𝑭𝑫𝑵𝑩 Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 3rd Stage: The merged bubble is a unity-Bubble Stem. 𝒇 = 𝟏𝟑. 𝟒𝟕𝒔−𝟏 [11 ,the merged bubble stem is treated as one bulk. 2nd Stage: Difficult to define the exact diameter. Bubbles followed a random pattern neither discretely nor as bubble stems. 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Experimental Phenomena 3rd Stage: The merged bubble is a unity-Bubble Stem. 𝒇 = 𝟏𝟑. 𝟒𝟕𝒔−𝟏 [11 ,the merged bubble stem is treated as one bulk. Critical Heat Flux 𝒒𝑭𝑫𝑵𝑩 < 𝒒 < 𝒒𝑪𝑯𝑭 Fully Developed Nucleate Boiling 2nd Stage: Difficult to define the exact diameter. Bubbles followed a random pattern neither discretely nor as bubble stems. 𝒒𝑳𝑯𝑭 < 𝒒 < 𝒒𝑭𝑫𝑵𝑩 1st Stage: Bubbles tend to be discrete. Experimental data can be patched into CFD models for a more accurate verification. Low Heat Flux 𝒒 < 𝒒𝑳𝑯𝑭 40 35 Tolubinsky & Kostanchuk(1970) Lee, et al.(2003) Kim, et al.(2006) Discrete Bubbles Bubble Stem Dd (mm) 30 25 For low heat flux: 𝑓 =Experimental Data 𝐷𝑑 = 0.007𝐽𝑎2 − 0.024𝐽𝑎 + 0.92 ; For fully developed nucleate boiling: 𝑓 = 13.47𝑠 −1 𝐷𝑑 = 2.526𝐽𝑎2 − 64.74𝐽𝑎 + 437.63 . 20 1.5 1.0 0.5 0.0 0 5 10 15 Ja [1] Jin T, Zhang S Y, Tang K, et al. Observation and analysis of the detachment frequency of coalesced bubbles in pool boiling liquid nitrogen[J]. Cryogenics, 2011, 51(9): 516-520. Boiling Models Area of influence: 𝜋 𝐴𝑏 = 𝐾𝑁𝐴 4 𝐷𝑑2 , 𝐾 = 4.8𝑒 Nucleate side density: h 𝜌𝑣 𝑇𝑤 −𝑇𝑙 𝑁A = 𝐶 ∙ fv σT sat −16 C = 625 × 10 . 𝐽𝑎 80 − 3 Bubble departure diameter 𝐷𝑑 = 0.007𝐽𝑎2 − 0.024𝐽𝑎 + 0.92 𝐷𝑑 = 2.526𝐽𝑎2 − 64.74𝐽𝑎 + 437.63 Compared with the observations, the existing correlations are far from satisfactory. Data is correlated based on our experimental results. Bubble departure frequency Similar to the situations of the departure diameter, the bubble departure frequency is also obtained from our experimental results. Research Procedures 𝒇𝒅 𝟏/𝟐 𝑫𝒅 = 𝑪 ∙ 𝒇(𝑱𝒂) 𝟑𝝅𝜶𝒍 Research Procedures 𝒇𝒅 𝟏/𝟐 𝑫𝒅 = 𝑪 ∙ 𝒇(𝑱𝒂) 𝟑𝝅𝜶𝒍 Research Procedures 𝒇𝒅 𝟏/𝟐 𝑫𝒅 = 𝑪 ∙ 𝒇(𝑱𝒂) 𝟑𝝅𝜶𝒍 Research Procedures 𝒇𝒅 𝟏/𝟐 𝑫𝒅 = 𝑪 ∙ 𝒇(𝑱𝒂) 𝟑𝝅𝜶𝒍 Results & Conclusions Heat Flux (W/m2) 106 Experiment CFD Simulation:fixed super-heat CFD Simulation:fixed heat flux The measured relation between heat flux and super-heat accorded well with the previous reported experimental data by other researchers. Three different boiling stages with different bubble departure structure were distinguished. The modeled relations between heat flux and super-heat for LN2 pool boiling were in good accordance with the measured data. 105 3rd Stage 2nd Stage 104 Experimental results from Reference Fitting line from Reference 1st Stage 103 2 3 4 5 6 7 8 9 Super-heat (K) 10 11 12 Thank You
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