平行流蒸发器制冷剂流量分配特性

Characteristics of Refrigerant Flow Distribution in Parallel Flow Evaporator

摘要:

采用标准kε模型和Eulerian模型对平行流蒸发器集管内两相制冷剂分配特性进行模拟，发现在集管加入分流管后，制冷剂流量分配不均匀性得到明显改善.在此基础上，分别对扁管插入集管的深度、分流管开孔率对流量分配的影响情况展开分析.发现当扁管伸入集管深度大约在分流管下方1/2时流量分配均匀性最好；对比不同开孔率时的流量分配情况，发现随着开孔率的增大流量分配均匀性先变差后变好，之后随着开孔率进一步增大，流量分配均匀性又变差.分流管在小开孔率下，需要注意与制冷系统中节流阀的匹配.

关键词:平行流蒸发器; 计算流体力学; 两相流; 分流管; 扁管插入深度; 开孔率

Abstract:

The standard kε-turbulence model and the two phase flow Eulerian model are used to simulate the refrigerant distributions in the heads of parallel-flow evaporators, and the experimental results in literature is used to validate the numerical method. Then, the comparison of distributions between base line structure and the structure with perforated tube in heads is conducted and the reason behind the performance improvement of the structure with perforated tube is revealed. The comparison of flow distribution in heads with perforated tubes in the open ratio ranging from 0.11 to 1.00 indicates that the uniformity of flow distribution decreases at first and then increases, after which it worsens with the further increase of open ratio. The matching issue of expansion valve with refrigerant systems should be concerned under the condition of small open ratio of perforated tubes.

Key words:parallel-flow evaporator; computational fluid dynamics (CFD); two-phase flow; perforated tube; depth of pipe insertion into the header; open ratio