When steam-water two-phase mixtures flow in inclined or horizontal rubes that are heated by alternation current, the circular angle-dependent temperatures on the outer radius imply that the inner heat transfer coefficients also cary with circular angle. The inner heat transfer coefficients are difficult to measure directly, but may be determined with the aid of inverse heat conduction theory. The direct model calculates the temperature field inside a half-pipe. This is subjected to a given teat transfer coefficient angular profile on its inner radius. The inverse heat conduction model calculates the temperature field under the conditions of the measured discrete temperatures and the heat-insulated boundary on the outer radius. Variation of the cylinder heat conductivity and specific resistance versus temperatures are considered in both models. The prediction accuracy is analyzed with a numerical test. The inverse heat conduction problem solution is verified as a useful tool for obtaining the inner heat transfer coefficient.

The transient two-fluid model has been used to develop a general relation for acoustic waves with steam-water two-phase mixture in one-dimensional flowing system. The analysis is valid in principle over the whole void fraction region. Both the mechanical and thermal nonequilibrium are considered. The vapor-liquid interface heat flux is derived from the one dimensional Fourier heat conduction equation to evaluate the interphase evaporation or condensation rate. Calculations are performed for pressures from 0.07 to 16.0MPa, void fractions from 0.0 to 1.0. Higher frequency limit of sonic velocities are only relied on the pressures and void fractions, and are insensitive to the bubble radius, tube diameter, and the velocity difference between the two phases. The predicted sonic velocities are compared with some experimental data for low pressures. Good agreement has been achieved between the predictions and the experimental data.

The present article is aimed at evaluating six typical flow boiling heat transfer correlations selected from the open literature with experimental results. The selected correlations are correlations of Chen, Shah, Gungor and Winterton, Liu and Winterton, Klimenko, and Kandlikar. Experiments of upward flow boiling heat transfer with kerosene in a vertical smooth tube were conducted. The test tube has a length of 2.5m and its outer and inner diameters are 19mm and 15mm, respectively. The experiments were performed at an absolute atmospheric pressure of 3. The input heat flux ranged from 28.5 to 93.75kW/m2 and the mass fluxes were selected at 410, 610, and 810kg/m2 s, respectively. The experimental flow boiling heat transfer coefficients were compared with flow boiling heat transfer coefficients calculated with the six typical correlations. By comparison, the most suitable correlations are recommended for the calculation of flow boiling heat transfer coefficients with kerosene in a smooth tube.

Experiments of upward flow boiling heat transfer with water in a vertical smooth tube and a tube with axial microgrooves were conducted. Both of the tested tubes have a length of 2.5m, an inner diameter of 15mm, and an outlet diameter of 19mm. The tube with axial microgrooves has many micro rectangle grooves in its inner wall along the axial direction. The grooves have a depth of 0.5mm and a width of 0.3mm. The tests were performed at an absolute pressure of 6bar. The heat flux ranged from 0 to 550kW/m2 and the mass flux was selected at 410, 610, and 810kg/m2s. By comparison, flow boiling heat transfer coefficients in the enhanced tube are 1.6 to 2.7-fold that in the smooth tube, while the frictional pressure drop in the enhanced tube is slightly greater than that in the smooth tube. The augmentation of flow boiling heat transfer in the tube with axial microgrooves is apparent. Based on the experimental data, a correlation of flow boiling heat transfer is proposed for the enhanced tube. Finally, the mechanisms of heat transfer enhancement are analyzed.

Experiments of flow boiling heat transfer and two-phase flow frictional pressure drop in a spirally internally ribbed tube (φ22×5.5mm) and a smooth tube (φ19×2mm) were conducted, respectively, under the condition of 6×105Pa (absolute atmosphere pressure). The available heated length of the test sections was 2500mm. The mass fluxes were selected, respectively, at 410, 610 and 810kg/m2s. The maximum heat flux was controlled according to exit quality, which was no more than 0.3 in each test run. The experimental results in the spirally internally ribbed tube were compared with that in the smooth tube. It shows that flow boiling heat transfer coefficients in the spirally internally ribbed tube are 1.4-2 times that in the smooth tube, and the flow boiling heat transfer under the condition of smaller temperature differences can be achieved in the spirally internally ribbed tube. Also, the two-phase flow frictional pressure drop in the spirally internally ribbed tube increases a factor of 1.6-2 as compared with that in the smooth tube. The effects of mass flux and pressure on the flow boiling heat transfer were presented. The effect of diameters on flow boiling that transfer in smooth tubes was analyzed. Based on the fits of the experimental data, correlations of flow boiling heat transfer coefficient and two-phase flow frictional factor were proposed, respectively. The mechanisms of enhanced flow boiling heat transfer in the spirally internally ribbed tube were analyzed.

In this study a computer program. HaGuo Start-up Simulation Program (HGSSP) for thermal-hydranlic analysis is developed for simulation of star-up behavior of a once-through bolier equipped with various integral separator start-up systems. With the simulation results, design principles for optimizing a start-up system for design and optimization of start-up procedures for operation, which will result in minimum start-up losses by reducing the start-up time as much as possible, can be obtained. On the basis of Dolezal's model, an improved analytical-numerical method is proposed to solve the coupled energy equations for flue gas and working fluid describing the transient hear transfer ocurrig in individnal heation surfaces. In order to verify the program presented here, the cold start of a 600-MW supercritical once-through boiler located in China on July 6, 1993. is sinudated and a comparison with measured adta made. This comparison indicates reasonable agreement between the computational main steam pressure, water separator level, and drain flow. Economizer inter and outlet temperatures. Economizer pressure, and final superheater inlet temperature and those measured. Finally, the standard cold and hot start-up processes of a Harbin Boiler Works supercritical once-through boiler are simulated with HGSSP to acquire the start-up curves and suitable drain valve dimensions corresponding to a predetermined pressure-raising curve.

In this paper a RPV model on the scale of 1:10 with safety injection nozzle directly connected with it was established. Three experiments including flow visualization, heat transfer at ambient temperature and pressure, and heat transfer at high temperature and pressure were performed. Based on the test results, the numerical simulations to study the transient heat transfer and flow characteristics by using the commercial fluid dynamic software FLUENT 5.4 were conducted. In flow visualization experiments, the effects of the injection velocity, the fluid velocity and void fraction in the downcomer annulus on the transient flow were obtained. In heat transfer experiments at ambient temperature and pressure, the heat transfer coefficient profile by using a heat flux meter, and the mixing function profile by using hot water injection to the RPV were determined. In heat transfer experiments at high temperature and high pressure, the transient temperature change in the downcomer annulus of RPV was investigated. In the work of numerical simulations the transient fluid temperature, wall temperature and heat transfer coefficient profile of the RPV during safety injection were determined. The results from the research may be used for the PTS analysis of RPV.

为了研究紊流横向射流的流动与传热特征，基于控制容积法和协调一致的求解压力耦合方程的半隐方法（SIMPL EC），应用标准k-ε模型、重整化群（RN G）k-ε模型和易实现的（Realizable） k-ε模型，对射流与主流动量通量比为0.5～10.0的二维横向射流传热进行了数值模拟。通过考察二维横向射流的平均流动和紊流特性，分析了回流区对射流下游壁面换热的影响，从流动机理角度解释了壁面换热峰值点位于重接触点近上游的现象，并结合横向射流特征讨论了3种紊流模型的优劣。计算结果表明，RN G k-ε和Realizable k-ε模型，尤其是Realizable k-ε模型的预测值比标准k-ε模型的预测值更为准确。

对锅炉热力过程采用解析——数值混合计算方法建立了计算数学模型。该模型的基础是通过管壁温度的求解解除冷侧流体与热侧流体能量方程之间的耦合关系，然后采用解析——数值混合计算方法分别求解冷热两侧流体能量方程。利用该方法计算了一台600MW超临界直流锅炉冷态启动过程，结果表明计算值与测量值吻合得比较好，而且与迭代解法的计算结果相差不大，但计算时间则大为缩短。

利用高压汽水两相流试验系统模拟压水堆小破门失水事故中冷凝回流传热模式，进行了传热、流动及不凝结气影响的试验。实验表明：冷凝回流传热是一种十分有效的传热模式，它在很小的一、二次侧温差时就能排放大量堆芯余热，冷凝回流系统在正常情况下流动阻力很小且稳定，但在达到回流动极限后出现不稳定。不凝结气的存在将大大降低蒸汽发生器的传热的能力，但一般情况下，系统能自动增加一次侧压力而达到排除余热的目的。