螺旋波纹管流动与对流传热场协同的数值模拟

发布时间：2018-01-19 04:19

本文关键词： 螺旋波纹管强化换热场协同超临界压力　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：强化换热越来越多的应用于各种换热设备中,以达到提高换热效率,节约能源的目的。对于螺旋波纹管内流体的运动,由于其螺旋凹槽结构的影响,使得管内的流动换热规律与光滑圆管有所不同。本文基于FLUENT软件对不同压力下单相水和超临界压力流体螺旋波纹管内的流动和换热进行数值模拟,对比分析了考虑粘性修正的换热关联式、标准k-ε湍流模型和RNG k-ε湍流模型的数值模拟结果,决定选用应用RNG k-ε湍流模型进行数值模拟。对不同压力下单相水在螺旋波纹管与光滑圆管的流动换热进行对比,得出螺旋波纹管具有强化换热的作用,研究了入口速度、温度和螺旋波纹管的结构参数等对径向速度、温度、湍动能、湍流耗散率率等的影响。并且采用综合性能指标PEC,熵产,火积值耗散以及场协同的理论对强化换热的效果进行评价分析。结果表明:在模拟所用的螺旋波纹管结构参数下,换热增强了1.5-2.7倍,摩擦压力增大了1.3-4.5倍,所有结构参数下的螺旋波纹管PEC均大于1.采用协同角,熵产,火积耗散均能对结构参数等对换热的影响进行较好的预测。在超临界压力下,选用k-ωSST湍流模型对拟临界温度附近的水的流动换热进行了数值模拟,对径向方向上速度、温度、以及壁面温度,壁面传热系数等的分布规律进行了研究。发现:在拟临界温度区域螺旋波纹管内速度呈现出中心低沿壁面逐渐增高,当靠近壁面处发生回落的变化趋势。
[Abstract]:Enhanced heat transfer is more and more used in all kinds of heat transfer equipment to improve heat transfer efficiency and save energy. For the movement of fluid in spiral bellows due to the influence of its spiral groove structure. The flow heat transfer in the pipe is different from that in the smooth pipe. The flow and heat transfer in the spiral bellows under different pressures are simulated by FLUENT software. The numerical simulation results of heat transfer correlation, standard k- 蔚 turbulence model and RNG k- 蔚 turbulence model with viscosity correction are compared and analyzed. RNG k- 蔚 turbulence model is chosen to simulate the flow heat transfer of single-phase water in spiral corrugated tube and smooth circular tube under different pressures. It is concluded that spiral bellows can enhance heat transfer. The inlet velocity, temperature and structural parameters of spiral corrugated tube are studied on radial velocity, temperature and turbulent kinetic energy. The effects of turbulence dissipation rate and entropy production were also studied. The effect of enhanced heat transfer is evaluated and analyzed by the theory of fire product dissipation and field cooperation. The results show that the heat transfer increases by 1.5-2.7 times under the structural parameters of spiral bellows used in simulation. The friction pressure increased by 1.3-4.5 times, and the PEC of spiral bellows under all structural parameters was greater than 1.The synergistic angle and entropy production were used. The effect of structure parameters on heat transfer is well predicted. Under supercritical pressure, K- 蠅 SST turbulence model is used to simulate the flow heat transfer of water near the pseudo-critical temperature. The distribution of velocity, temperature, wall temperature, wall heat transfer coefficient and so on in radial direction are studied. It is found that the velocity of spiral bellows in the pseudo-critical temperature region increases gradually along the wall. When near the wall, the trend of falling back.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK172

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