Capillary tubes are widely used as throttle device in small heat pumps. A reliable and predictive capillary model within an overall heat pump model can reveal the design potential of the capillary towards an optimized heat pump operation. A flow model is presented that predicts the single and two-phase flow of propane through a straight copper capillary tube of 1.1799 mm inner diameter and 1 m length that evokes a pressure drop. An extensive and precise experimental database is generated by thorough experiments also providing refined specifications of the inner diameter and roughness of the capillary tube. Experiments are carried out for inlet pressures of 16-25 bar, mass flows of 13.5-18 kgh${}^{-1}$ (3430-4573 kgm${}^{-2}$s${}^{-1}$) and subcoolings of 5-9 K. Based on the generated experimental database, multiple common two-phase viscosity correlations are evaluated within the flow model. A proposed modified two-phase viscosity correlation results in the best fit of experimental and predicted the flow of propane through the capillary with a mean relative error of only 4 %.

毛细管被广泛用作小型热泵中的节流装置。整体热泵模型中的可靠且可预测的毛细管模型可以揭示毛细管朝着优化的热泵运行的设计潜力。提出了一种流动模型，该模型预测了丙烷通过内径为1.1799 mm，长度为1 m的直铜毛细管的单相和两相流动，这​​会引起压降。通过全面的实验生成了广泛而精确的实验数据库，还提供了毛细管内径和粗糙度的详细说明。实验的入口压力为16-25 bar，质量流量为13.5-18 kgh${}^{-\mathrm{1个}}$ （3430-4573公斤${}^{-2}$s${}^{-\mathrm{1个}}$）和5-9 K的过冷度。基于生成的实验数据库，在流动模型中评估了多个常见的两相粘度相关性。提出的改进的两相粘度相关性可实现最佳的实验拟合，并预测丙烷通过毛细管的流量，平均相对误差仅为4％。