A combined CFD/visualization investigation of heat transfer behaviors during geyser boiling in two-phase closed thermosyphon

Wang, Xiaoyuan; Wang, Yinfeng; Chen, Haijun; Zhu, Yuezhao

doi:10.1016/j.ijheatmasstransfer.2018.01.005

Cited by 99 publications

(16 citation statements)

References 26 publications

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“…The oscillation period is varied from tens of seconds to hundreds of seconds. The wall temperature oscillation at the condenser section has been frequently reported by thermosyphon heat pipe operating at sub‐atmospheric pressure 20‐24 . At the sub‐atmospheric pressure condition, density ratio between liquid and vapor is large, and bubble size remarkably expands compared to atmospheric pressure condition.…”

Section: Resultsmentioning

confidence: 97%

Effective energy management design of spent fuel dry storage based on hybrid control rod‐heat pipe

Kim

Bang

2020

Int J Energy Res

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Spent fuel dry storage cask, which stores the spent fuel from wet storage facility to final processing, has been developed and managed. Even though thermal management mechanisms of dry storage casks secure the thermal integrity of the cask, improvement of thermal management capacity of dry storage cask would enhance thermal margin against unforeseen off-normal conditions with increasing specific storage capacity. Ulsan National Institute of Science and Technology (UNIST) CANister (UCAN) utilizing the new-type thermosyphon heat pipe, is under development as an advanced design of spent fuel dry storage cask. Hybrid control rod-heat pipe, which is an annular thermosyphon by containing neutron absorber, is a key component of UCAN. Heat removal performance of the hybrid control rod-heat pipe was analyzed bya series of experiment withtest facility simulating single fuel assembly with full height. The UCAN fuel assembly showed the reduced structural and fuel temperatures compared to bare fuel assembly of conventional cask designs, exhibitingimproved thermal margin. According to experimentally observed heat removal rate of the hybrid control rod-heat pipe, UCAN design could extend manageable thermal capacity from 13.3% to 33.8%. The removeddecay heat through hybrid control rod-heat pipe could be reused in electricity generation with stirling engine and thermoelectric devices improving energy management efficiency. Intermittent boiling accompanying geyser phenomena was frequently occurred inside the test section, and the boiling behaviors according to fill ratios (FRs) and operating pressures dominated the heat removal performances. The hydrostatic pressure owing to large aspect ratio affected differentiated thermal-hydraulic behaviors compared to conventional thermosyphons. To develop heat transfer and hydraulic models of the hybrid control rod-heat pipe, geyser phenomenon inside the test section wasdiscussed physically. This workexhibited the feasibility of UCAN design and provides fundamental physics on intermittent boiling of thermosyphon operating at sub-atmospheric pressures.

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Section: Resultsmentioning

confidence: 97%

Effective energy management design of spent fuel dry storage based on hybrid control rod‐heat pipe

Kim

Bang

2020

Int J Energy Res

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“…Kafeel et al [6] studied the heat transfer characteristics of a thermosyphon under different pulsed heat increments; moreover, they simulated the evaporation and condensation process of a thermosyphon with the Eulerian model, considering the effects of evaporation, condensation, heat transfer and mass transfer at the interface in the two-phase region. Wang et al [7] used the modified Lee model based on the volume of fluid (VOF) method and the original Lee model to model the heat transfer behavior of a thermosyphon during geyser boiling via computational fluid dynamics (CFD). Limin et al [8] established a transient simulation model of a thermosyphon using SINDA/FLUINT 5.6.…”

Section: Introductionmentioning

confidence: 99%

Evaluation model of the steady-state heat transfer performance of two-phase closed thermosyphons

Zhu

et al. 2022

THERM SCI

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Two-phase closed thermosyphons have good thermal conductivity and are widely used in heat transfer applications. It is essential to establish an effective method for evaluating the steady-state heat transfer performance of two-phase closed thermosyphons, as such a method can help to select appropriate designs and to improve the efficiency of these devices. In this paper, the equivalent thermal conductivity is derived by the principle of equal total thermal resistance, in which the influence of the adiabatic length is eliminated. An evaluation model of the steady-state heat transfer performance of two-phase closed thermosyphons is established. Test results of three two-phase closed thermosyphons with total lengths of 220 mm, 320 mm and 500 mm show that as the heat transfer rate increases, the equivalent thermal conductivity of these devices decreases by 28.91%, increases by 6.10% and increases by 10.02%, respectively, among which the minimum value is 831.63 W?m-1?K-1and the maximum value is 1694.19 W?m-1?K-1. The decrease (increase) in the equivalent thermal conductivity in the evaluation model indicates a decrease (increase) in the heat transfer performance. The results show that the equivalent thermal conductivity of the model can effectively evaluate the heat transfer performance of two-phase closed thermosyphons.

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“…Their results showed that the thermal response of the wall‐implanted heat pipe is faster on the basis of the heat transfer rate of 1.1 kW/m 2 , as compared with the conventional wall. Wang et al 9 implemented coupling between the CFD and visualization to investigate geyser boiling in a closed thermosiphon with a two‐phase flow. The results indicated that geyser boiling started at the cycle time ranging from 80 to 100 seconds, with an evaporator temperature of 95°C and a condenser temperature of 30°C.…”

Section: Introductionmentioning

confidence: 99%

Assessment of heat transfer and flow characteristics of a two‐phase closed thermosiphon

Ahmed

Jubori

2020

Heat Trans

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In this study, comprehensive modeling and simulations were developed and carried out to perform the investigation of the thermal performance of the enclosed thermosiphon through pool boiling in the evaporator sector and the condensation of the liquid film in the condenser part. To simulate these phenomena, the volume of fluid model was utilized. The simulation modeling using the computational fluid dynamics (CFD) technique was validated with existing experimental results, and a good agreement was reached. The simulation results were presented and evaluated in terms of temperature profiles and contours, the volume of fraction contours, and velocity vector distribution. Moreover, the thermal performance (ie, the heat transfer coefficient and thermal resistance) through the thermosiphon operation was analyzed. From the simulation results, it is found that the thermosiphon performance can be improved by the tilt angle and fill ratio. The results indicated that the optimal performance (ie, a high heat transfer coefficient and a low thermal resistance) was attained at a power input of 250 W, tilt angle of 90°, and fill ratio of 0.5. The established CFD simulations effectively predicted the formation of two‐phase flow pattern and boiling and condensation zones with water at a low power input, termed as geyser boiling.

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A combined CFD/visualization investigation of heat transfer behaviors during geyser boiling in two-phase closed thermosyphon

Cited by 99 publications

References 26 publications

Effective energy management design of spent fuel dry storage based on hybrid control rod‐heat pipe

Effective energy management design of spent fuel dry storage based on hybrid control rod‐heat pipe

Evaluation model of the steady-state heat transfer performance of two-phase closed thermosyphons

Assessment of heat transfer and flow characteristics of a two‐phase closed thermosiphon

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