摘要
为保证在事故工况下非能动余热排除系统有效导出余热,对其主要设备PRHR热交换器进行换热特性研究,建立了非能动余热排出系统C型管换热器的内外耦合传热分析模型,采用一维均相流模型计算管内冷凝换热与CFD程序分析水池空间的自然对流。研究进口质量流量、进口流体含气率、管倾角和水箱温度对C型管换热器换热特性的影响。结果表明:C型管换热器入口倾斜段管内始终为饱和的两相流体,在竖直段与出口倾斜段,管内流体温度逐渐下降;管内压力、流体焓值和换热系数沿管长逐渐降低;大约在冷凝70 s后,管内流体参数趋于稳定;管壁温度在入口倾斜段迅速下降,在竖直段和出口段趋于平缓。增大进口质量流量与进口流体含气率,流体温度、流体焓以及管内外换热系数增加,并且沿流动方向受两者的影响逐渐减小;若管倾斜角度增大20°,出口倾斜段管内流体温度下降约3℃;当水箱温度升高10℃,汽泡生成与脱离速度加快,水箱内部换热增强,入口倾斜段外壁温升高2℃左右,出口倾斜段外壁温大约升高0.2℃。CFD模拟结果展示出水箱内汽泡大部分聚集在C型管上部并逐渐向上流动,致使热流体向上运动,冷流体向下流动,形成自然循环。
To guarantee the effective heat conduction of residual heat from a passive residual heat removal system under the accidental operating conditions,studied were the heat exchange characteristics of the main equipment item,i. e. the PRHR heat exchanger and established was a model for analyzing the inner and outer coupled heat transfer of Cshaped tube heat exchangers in a passive waste heat discharging system. In this connection,a one-dimensional homogeneous phase flow model was employed to calculate the condensation heat exchange inside the tubes and the CFD program was used to analyze the natural convection in the space of a water pool. In addition,the influence of the mass flow rate at the inlet,gas content of the fluid at the inlet,the inclination angle of the tubes and the temperature inside the water box on the heat exchange performance of the C-shaped tube heat exchanger was also studied. It has been found that a saturated two-phase flow always exists inside the tubes in the inclined section at the inlet of the C-type tube heat exchanger,the temperature of the fluid inside the tubes in the vertical section and the inclined section at the outlet will gradually decline,the pressure inside the tubes,enthalpy value of the fluid and the heat exchange coefficient will drop step by step along the tube length direction,the parameters of the fluid in the tubes will tend to be stable after a condensation for about 70 seconds,the temperature on the tube walls will quickly drop in the inclined section at the inlet and tend to be slow and smooth in the vertical section and the section at the outlet. Furthermore,to increase the mass flow rate and the gas content of the fluid at the inlet,the temperature and enthalpy of the fluid as well as the heat exchange coefficients inside and outside the tubes will increase and the influence of both mass flow rate and gas content will gradually decrease. If the inclination angle of the tubes increases by 20 degrees,the temperature of the fluid inside the inclined tube section at the ou
出处
《热能动力工程》
CAS
CSCD
北大核心
2016年第7期22-29,131-132,共8页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金资助项目(51176052
51376065)
广东省科技公关基金资助项目(2013B010405004)
关键词
C型换热器
耦合传热
冷凝传热
自然对流
C-shaped tube heat exchanger
coupling heat transfer
condensation heat transfer
natural convection
