[en] The experimental results for the initial point of net vapor generation in up-flow subcooled boiling in an internally-heated annulus are given. The characteristics of the initial point of net vapor generation and the problem on gamma ray attenuation measurement are discussed. The comparison between the data and a calculation model is given, it is showed that the data agree well with the model

[en] Miniaturization technique of condenser is presented. By means of experimental research of condenser model, the results of experimental research for spiral tube condenser are given; and the work characteristic and the results of heat transfer enhancement of the condenser are analysed. The experimental results have important significance for the practical use of the spiral tube condenser

[en] The exergy method of analysis is based on the second law of thermodynamics. It answers the questions of where, why, and how much of this available work is lost in actual systems. This is the information required to design and operate more efficient systems from the energy-saving viewpoint. The paper discusses the application of the energy method in PWR NPP thermodynamical analysis. The evaluated energy loss of Qinshan NPP, indicates that PWR is the most inefficient equipment in the whole power system, and that the energy loss is due to the irreversibility of energy transfer and transformation processes. Finally some possible ways of improving the PWR NPP are put forward

[en] Highlights: • Six circulation modes were identified in an open loop. • Flashing and geysering are the determinants of flow characteristics. • The evolution of circulation modes was discussed. • Suppressing geysering facilitates the emergence of continuous flashing. • By taking into account subcooling, flashing and heat dissipation, the average circulation flowrate was predicted well. - Abstract: Flow characteristics are relevant to the safe operation of natural circulation systems. Experimental research on flow characteristics in an open natural circulation loop was conducted. It was shown that flashing and geysering are the two fundamental phenomena influencing the flow characteristics; in addition, flashing and geysering interact reciprocally: geysering weakens the impact of flashing on the flow, while flashing can suppress geysering. Six circulation modes were identified based on the weight of flashing and geysering, as well as typical inlet flowrate curve and experimental observations. As the heating power varies, so do the weights of flashing and geysering, which result in variable flow behavior and the evolution of circulation modes. Based on the theoretical analysis and the calculation of average circulation flowrate by taking into account the effects of subcooling, flashing and heat dissipation, suggestions for the operating and improvement of the system were proposed.

[en] Considering the special resistance characteristics of fluids flowing through ducts with small gap sizes, experiments are performed to study the resistance characteristics of single-phase water, which is forced to flow through vertical annuli. The results show that the transition to turbulent flow is initiated at Reynolds number of 900-1100, and the flow resistance in annulus has little relations with the temperature difference and heated modes, but mainly depends on the ratio of mass velocity to the width of annulus

[en] Highlights: • The effect of wall subcooling on HTC under low wall subcooling degree is stronger than Nusselt analysis. • New empirical correlation for steam condensation over a vertical tube external surface under low wall subcooling degree have been developed. • There is no noncondensable gases stratification phenomenon during all the present experiments. - Abstract: Experimental investigations have been conducted to study the steam heat removal capacity with noncondensable gases (e.g. air, helium) under low wall subcooling over a vertical tube external surface. The effect of the wall subcooling on the steam condensation heat transfer coefficients has been researched by experiments when the pressure and the air mass fractions are stable. At the air/steam cases, condensation heat transfer coefficient has been obtained under the wall subcooling degree ranging from13 to 25 °C, total pressure ranging from 0.4 MPa to 0.6 MPa and air mass fraction ranging from 0.07 to 0.52. Under the same pressure and noncondensable gases mass fraction, the effect of wall subcooling on condensation heat transfer coefficient with noncondensable gases is stronger than that with pure steam. The empirical correlation is developed for the heat transfer coefficient which covered all data points within 15%. Under air/helium/steam cases, the effect of helium (simulating hydrogen) on the heat transfer coefficient is investigated under the wall subcooling degree ranging from 18 to 27 °C, total pressure ranging from 0.53 MPa to 0.6 MPa, steam mass fraction ranging from 0.6 to 0.92 and helium volume fraction in noncondensable gases keeping 0.3. None of the experimental conditions is found the helium stratification. The condensation heat transfer coefficient that got from steam/air/helium condition is about 20% lower than that got from air/steam cases

[en] The influence of main factors on overall heat transfer was analyzed, and the effects of fouling factors on heat transfer characteristics in steam condenser were clarified. It was proposed that the tube outside enhancement is the most important attribute, when outside heat transfer coefficient increased there will be a big increase in condenser efficiency. The characteristics of heat transfer enhancement by spirally indented tube were investigated. It was proposed that condenser heat transfer efficiency will be raised when the low fin tube or the spirally indented tube with special treated surface were used

[en] The effects of diameter and air inlet on flooding and flow reverse have been studied by experiment. Experimental results indicated that when resistance reduced at the air inlet, air flow rate at the onset of flooding will rise in some conditions. On right angle, the inlet conditions do not effect flooding points. When air inlet is well-rounded, the tube diameters have effects on the points. Air inlet has effects on complete carry up, but tube diameter no effects on that, the smaller of diameter, the larger of J_g^* in complete carry up. Diameter and air inlet have no effects on flow reverse. Air inlet does not effect flooding but the tube diameter does

[en] Two-phase countercurrent flow in reactor hot leg at loss of coolant accident is studied by experiment and analysis. The test section consists of a vertical tube, an inclined tube and a horizontal tube. It is found that the length of horizontal tube has significant effects on the onset of flooding. The experimental research and theoretical analysis on the onset of flooding were done. Analysis and comparison of calculation model are given. The correlation for calculating the onset of flooding in reactor hot leg is recommended

[en] Considering the special heat transfer characteristics of fluids flowing through ducts with small gap sizes, experiments are performed to investigate the heat transfer characteristics of single-phase water, which is forced to flow through vertical annuli with gap size of 0.9 mm and 2.4 mm. The results show that narrow annulus can enhance the single-phase heat transfer, but instead of further enhancing the heat transfer, the annulus with gap size of 0.9 mm weakens the enhancement