人字形波纹板间海水蒸发传热特性模拟

Numerical simulation on evaporation and heat transfer characteristics of seawater in corrugated plate evaporator

板式蒸发器越来越多地用于海水淡化系统中,但因其海水蒸发过程涉及复杂的两相流,通过数值模拟的方法研究仍存在一些难题。对板式蒸发器内相邻两互相倒置的人字形波纹板间的流道建立三维物理数学模型,使用计算流体力学(CFD)方法研究海水在人字形波纹板间流道内的流动蒸发传热情况,分析人字形波纹板倾斜角和波纹板高度对海水在板式蒸发器内流动蒸发传热性能的影响。结果表明:由于触点的存在,产生较强的湍流;沿流动方向水蒸气质量分数不断增加,海水质量分数不断减少;波纹板高度越大越有利于海水蒸发时水蒸气的扩散,这种优势在流道入口速度大时更加明显;波纹板倾角为60°时的板片换热性能高于波纹倾角为30°的板片。该研究结果可为低温多效蒸馏板式海水淡化技术发展提供参考。

The plate evaporator is now becoming more dominant in the desalination market, but due to the complex heat transfer mechanism of two-phase flow, there are some difficulties in investigations on two-phase flow in the plate evaporator by simulation. Thus, a three-dimensional physical and mathematical model for the plate evaporator with corrugated plate was developed in this paper. The characteristics of flow and heat transfer of seawater through evaporation process in the above corrugated plate evaporator were researched by computational fluid dynamics （CFD） method, to reveal the effects of corrugated plate inclination angle and corrugation depth on seawater evaporating performance. The results show that, because of the existence of contacting points, strong turbulent is formed when the seawater flows down. In the flow direction, the water vapor＇s mass fraction continuously increases while that of the seawater decreases gradually. The greater corrugation depth is better for diffusion of the vapor evaporated from seawater. The advantage of greater channel width over evaporation shows obviously at the larger inlet velocity. The heat transfer performance of the corrugated plate with inclination angle β of 60° is greater than that with β of 30°. The research can provide reference for development of the low temperature multi-effect evaporation desalination.