叉流式新风换热器数值模拟

换热器是新风系统的核心部件,以某品牌新风换热器为模型,对该换热器进行数值模型,分析换热过程中换热和流动特性,以及流速、流道高度对换热性能的影响。建立不同流道高度时新风侧温差、压差、努塞尔数、阻力系数、综合传热性能因子随速度的变化关系。发现在换热器内存在"换热死区",随速度增加"换热死区"范围增大,在流速0.5m/s～1.6m/s、流道高度3mm～5mm范围内,增加流速可提高换热能力、减小阻力系数,但压降同样增加;相同速度时,提高流道高度不仅提高了换热性能,还减小了压降。

Numerical simulation of cross-flow fresh air heat exchanger

Heat exchanger is the core component of fresh air system.Taking a brand of fresh air heat exchanger as a model, the numerical model of the heat exchanger was carried out to analyze the heat transfer and flow characteristics of the heat exchang- er during heat exchange and the influence of flow velocity and runner height on heat transfer performance.The relationships among the temperature difference,the differential pressure,the Nusselt number,the drag coefficient and the comprehensive heat transfer performance factor of the fresh air side with different flow path heights were built.It is found that there is a "heat exchange dead zone"in the heat exchanger,and the range of "heat exchange dead zone"increases as the velocity increases.In the range of 0.5m/s ~1.6m/s and 3ram ~5mm flow path height,increasing the flow rate can increase the heat exchange capacity and reduce the drag coefficient,but the pressure drop increases with the increase of the speed.At the same velocity,the height of the flow path is not improved.The heat transfer performance also reduces the pressure drop.