The aim of this study is to experimentally investigate the oil influences on transport, heat transfer and distribution performances of microchannel evaporator. Mixture of R32 and PVE VG68 oil was selected as the working fluid, and two single-pass microchannel heat exchangers were used as test samples. The experiments were conducted in mass flux range of 20–50 kg·m⁻²·s⁻¹, nominal oil mass fraction (OMF_no) range of 0–6% and inlet local quality range of 0.1–0.16 at the saturation temperature of 12 °C. The result indicated that the oil retention volume ratio (ORVR) increases with the increments in oil mass fraction, inlet quality and decrease in mass flux. The upper outlet header tended to have remarkable oil retention and the oil transport behavior in header was analyzed. In most cases, the heat transfer was suppressed by the addition of oil. Heat transfer enhancement was observed at low oil mass fraction and high inlet quality conditions. The heat transfer factor ranged from 0.95 to 1.03, which indicated that the oil effect on heat transfer was not significant. Although the presence of oil inhibited the saturated boiling heat transfer coefficient, it could promote the heat transfer at superheat region. Struggle of inhibition and enhancement effects resulted in slight oil effect on heat transfer performance. An infrared-image-based distribution rating parameter was utilized to quantify the distribution performance. The oil effect on flow distribution was slight and the flow distribution deteriorated as the mass flux increased. A theoretical model called liquid immersion model was adopted to describe the flow regime and distribution mechanism in inlet header.

本研究的目的是通过实验研究油对微通道蒸发器的传输、传热和分布性能的影响。工作流体选用R32和PVE VG68油的混合物，两台单程微通道换热器作为试验样品。实验在 20–50 kg·m ^-2 ·s ^-1的质量通量范围内进行，标称油质量分数（OMF _no) 范围为 0–6%，入口局部质量范围为 0.1–0.16，饱和温度为 12 °C。结果表明，随着油质量分数、入口质量的增加和质量通量的降低，保油体积比（ORVR）增加。上出口集管趋于具有显着的保油性，并分析了集管内的输油行为。在大多数情况下，通过添加油来抑制传热。在低油质量分数和高入口质量条件下观察到传热增强。传热系数在0.95~1.03之间，表明油对传热的影响不显着。虽然油的存在抑制了饱和沸腾传热系数，但它可以促进过热区的传热。抑制和增强作用的斗争导致油对传热性能的影响很小。使用基于红外图像的分布评级参数来量化分布性能。油对流量分布的影响很小，随着质量通量的增加，流量分布恶化。采用一种称为液浸模型的理论模型来描述入口集管中的流态和分布机制。