Past researches have shown that CO₂/HFC mixtures and microchannel heat exchanger could benefit solving the problems of high operating pressure and relatively low cycle efficiency. In this paper, the supercritical heat transfer characteristics of R41, CO₂/R41 (20.5/79.5) and CO₂/R41 (51.4/48.6) in square porous flat tube microchannel with the hydraulic diameter of 0.715 mm were experimentally studied. The experimental conditions were as follows: the operating pressure of 6.5–7.5 MPa, the mass flow rate of 150–300 kg/m² s, the heat flux of 3–9 kW/m², the fluid temperature of 20–90 °C. The results show that, similar to pure CO₂, heat transfer coefficient (HTC) of mixtures also appears a peak value near the pseudocritical region. At higher operating pressure, the peak value is less and the change of HTC is gentle. Meanwhile, the inflection point temperature is high. When the bulk temperature is less than the inflection point temperature, HTC is higher at low operating pressure. When the bulk temperature is greater than the inflection point temperature, HTC is higher at high operating pressure. Peak value of HTC decreases and the inflection point temperature of mixtures becomes higher when the CO₂ mass fraction is low. With the increase of R41 mass fraction, the change of HTC is gentle. The width of the peak distance in the pseudocritical region becomes wider. The model of Petrov and Popov is recommended as the prediction model for CO₂/R41 mixtures. This research can serve as a database for the design of CO₂/R41 mixtures microchannel heat exchangers.

过去的研究表明，CO ₂ /HFC 混合物和微通道换热器有助于解决工作压力高和循环效率相对较低的问题。本文通过实验研究了R41、CO ₂ /R41 (20.5/79.5)和CO ₂ /R41 (51.4/48.6)在水力直径为0.715 mm的方形多孔扁平管微通道中的超临界传热特性。实验条件为：操作压力6.5-7.5 MPa，质量流量150-300 kg/m ² s，热通量3-9 kW/m ²，流体温度20-90° C。结果表明，类似于纯 CO ₂, 混合物的传热系数 (HTC) 在伪临界区附近也出现峰值。在较高的工作压力下，峰值较小，HTC 的变化平缓。同时，拐点温度高。当整体温度低于拐点温度时，HTC 在低操作压力下较高。当整体温度大于拐点温度时，HTC 在高操作压力下更高。当CO ₂质量分数较低时，HTC的峰值降低，混合物的拐点温度变高。随着R41质量分数的增加，HTC的变化是平缓的。伪临界区的峰距宽度变宽。推荐使用 Petrov 和 Popov 模型作为 CO 的预测模型₂ /R41 混合物。本研究可作为设计 CO ₂ /R41 混合物微通道换热器的数据库。