Heat transfer characteristics and operation limit of pressurized hybrid heat pipe for small modular reactors

Abstract In this paper, a hybrid heat pipe is proposed for use in advanced nuclear power plants as a passive heat transfer device. The hybrid heat pipe combines the functions of a heat pipe and a control rod to simultaneously remove the decay heat generated from the core and shutdown the reactor under accident conditions. Thus, the hybrid heat pipe contains a neutron absorber in the evaporator section, which corresponds to the core of the reactor pressure vessel. The presence of the neutron absorber material leads to differences in the heated diameter and hydraulic diameter of the heat pipe. The cross-sectional areas of the vapor paths through the evaporator, adiabatic, and condenser sections are also different. The hybrid heat pipe must operate in a high-temperature, high-pressure environment to remove the decay heat. In other words, the operating pressure must be higher than those of the commercially available thermosyphons. Hence, the thermal performances, including operation limit of the hybrid heat pipe, were experimentally studied in the operating pressure range of 0.2–20 bar. The operating pressure of the hybrid heat pipe was controlled by charging the non-condensable gas which is unused method to achieve the high saturation pressure in conventional thermosyphons. The effect of operating pressure on evaporation heat transfer was negligible, while condensation heat transfer was affected by the amount of non-condensable gas in the test section. The operation limit of the hybrid heat pipe increased with the operating pressure. Maximum heat removal capacity of the hybrid heat pipe was up to 6 kW which is meaningful value as a passive decay heat removal device in the nuclear power plants. Based on the experimentally measured maximum heat removal capacities, models predicting the operation limit (flooding limit) of the hybrid heat pipe were developed.

[1]  G. Wallis One Dimensional Two-Phase Flow , 1969 .

[2]  M. Morgan,et al.  Heat Transfer Characteristics in Two-Phase Closed Conventional and Concentric Annular Thermosyphons , 1989 .

[3]  Per F. Peterson,et al.  Gas-Concentration Measurements and Analysis for Gas-Loaded Thermosyphons , 1988 .

[4]  C. L. Tien,et al.  Non-condensable gas effect on condensation in a two-phase closed thermosyphon , 1984 .

[5]  Ioan Sauciuc,et al.  Temperature control using variable conductance closed two-phase heat pipe , 1996 .

[6]  Amir Faghri,et al.  Heat Pipe Science And Technology , 1995 .

[7]  Hideaki Imura,et al.  Critical heat flux in a closed two-phase thermosyphon , 1983 .

[8]  Mehdi Shanbedi,et al.  Investigation of Heat-Transfer Characterization of EDA-MWCNT/DI-Water Nanofluid in a Two-Phase Closed Thermosyphon , 2012 .

[9]  Xin-Rong Zhang,et al.  Experimental investigation of CO2 thermosyphon flow and heat transfer in the supercritical region , 2013 .

[10]  B. T. Chew,et al.  Performance dependence of thermosyphon on the functionalization approaches: An experimental study on thermo-physical properties of graphene nanoplatelet-based water nanofluids , 2015 .

[11]  Inseok Yang,et al.  Hydraulic operating temperature control of a loop heat pipe , 2015 .

[12]  Madhusree Kole,et al.  Thermal performance of screen mesh wick heat pipes using water-based copper nanofluids , 2013 .

[13]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[14]  A. Solomon,et al.  Thermal performance of a heat pipe with nanoparticles coated wick , 2012 .

[15]  Chuanping Liu,et al.  Effect of non-condensable gas on the start-up of a gravity loop thermosyphon with gas–liquid separator , 2016 .

[16]  C. L. Tien,et al.  Entrainment limits in heat pipes , 1978 .

[17]  A. F. Akon,et al.  PERFORMANCE OF HEAT PIPE FOR DIFFERENT WORKING FLUIDS AND FILL RATIOS , 2011 .

[18]  In Cheol Bang,et al.  Hybrid heat pipe based passive in-core cooling system for advanced nuclear power plant , 2015 .

[19]  Marcia B. H. Mantelli,et al.  Performance of naphthalene thermosyphons with non-condensable gases – Theoretical study and comparison with data , 2010 .

[20]  Yuichi Mitsutake,et al.  Enhancement of CHF in open thermosyphon with heated bottom chamber , 2000 .

[21]  I. Bang,et al.  Comparison of flooding limit and thermal performance of annular and concentric thermosyphons at different fill ratios , 2016 .