Poor distribution of two-phase flow in a microchannel heat exchanger header requires a solution to maximize its potential advantage of compactness while offering a high heat-transfer rate. While previous works have attempted to improve two-phase flow distribution, most have focused on horizontal headers, which commonly appear in indoor units. However, there are a few studies on vertical headers that function as an evaporator in heat pump mode that are typical in outdoor units. This study describes the development of a modified vertical header with a dual-compartment structure aimed at improving the flow distribution. Experiments and visualizations were conducted using R410A in a test section that represented the size and capacity of an actual heat exchanger. The inlet mass flux was 309–1235 kg·m⁻²s⁻¹ (50–200 kg·h⁻¹), vapor quality was 0.1–0.2, and the evaporating temperature was maintained at 15 °C. The results were compared to the conventional header previously evaluated by our research group. Results showed that the dual-compartment header was able to enhance the liquid flow distribution at low inlet mass flux from approximately 30% to 80% based on relative standard deviation (RSD), with a generally higher liquid Reynolds number when compared to the conventional header.

微通道换热器集管中两相流分配不佳，需要一种解决方案，以最大程度地提高其紧凑性的潜在优势，同时提供较高的传热速率。尽管先前的工作试图改善两相流的分布，但大多数都集中在水平集管上，该集管通常出现在室内机中。然而，对垂直集管的研究很少，这些集管在室外机中通常在热泵模式下用作蒸发器。这项研究描述了具有双隔室结构的改进型垂直集管的开发，旨在改善流量分配。使用R410A在代表实际热交换器的尺寸和容量的测试部分中进行了实验和可视化。入口质量通量为309–1235 kg·m ^-2 s^-1（50-200 kg·h ^-1），蒸汽质量为0.1-0.2，蒸发温度保持在15°C。将结果与我们的研究小组先前评估的常规接头比较。结果显示，基于相对标准偏差（RSD），双室联管箱能够在低入口质量通量下将液流分布从大约30％增强到80％，与常规联管箱相比，通常具有更高的液体雷诺数。