基于联合仿真的板翅式换热器换热特性模拟

Study on heat transfer characteristics of plate-fin heat exchanger based on joint simulation

为获得板翅式换热器整体结构内的流场与流量分配特性,采用联合仿真中MATLAB和FLUENT计算模型的流动和传热模块,在压力场和温度场相互耦合的情况下,以天然气为例分析板翅式换热器内部流量分配特性对换热的影响。研究表明:板翅式换热器内由于流量分配不均而引起的出口温度分布不均更为严重;天然气侧在不发生相变的情况下,因温度压力变化会使密度升高约10%,动力黏度降低13%;流量由小到大变化会使表面传热系数增加约1.9倍,计算微元压降增加约3.5倍;板翅式换热器内由于流量分配不均而出现的小质量流量和大质量流量都会造成换热效率下降,出现换热面积不能得到充分利用或天然气不能冷却到理想温度等问题。

In order to obtain the flow field and flow distribution characteristics in the overall structure of plate-fin heat exchanger,the flow and heat transfer modules in the MATLAB and FLUENT computational models in the joint simulation are adopted.Taking the natural gas as an example under the condition that the pressure and temperature fields are coupled,the influence of internal flow distribution characteristics on the heat transfer in the plate-fin heat exchanger is analyzed.The results show that the uneven distribution of outlet temperature in the plate-fin heat exchanger is more serious due to the uneven flow distribution.When the phase change does not occur on the natural gas side,the density would increase by about 10%,the dynamic viscosity would decrease by 13%,the surface heat transfer coefficient would increase by about 1.9 times,and the calculated micro-element pressure drop would increase by about 3.5 times due to the variation of temperature and pressure.Moreover,the small mass flow and large mass flow in the plate-fin heat exchanger due to uneven flow distribution will cause the decrease of the heat transfer efficiency,resulting in the insufficient utilization of heat transfer area or the failure of natural gas to cool to the ideal temperature.