给出了丙烷（R-290）、异丁烷（R-600a）以及丙烷和异丁烷的50/50混合物（按重量计）在沸腾和冷凝期间单相流（蒸汽和液体）和两相流的压力梯度。根据纯制冷剂文献中可用的标准关联式，给出了光滑管的压力梯度。制冷剂的质量流量在很大范围内变化，通常出现在住宅、商业和汽车应用中。蒸发温度为6.7°C（20°F）和4.4°C（40°F），冷凝温度为37.8°C（100°F）和48.9°C（120°F）。 将碳氢化合物R-290、R-600a和R-290/R-600a混合物的压力梯度与R-12和R-134a的压力梯度进行比较。NIST开发的REFPROP计算机程序用于确定R-290、R-600a和R-290/R-600a的热力学性质。研究表明，碳氢化合物的压力梯度明显高于R-12和R-134a。在所研究的制冷剂温度和质量流量范围内，碳氢化合物的单相蒸汽压梯度比R-12大153%至374%，比R-134a大123%至307%。与R相比，碳氢化合物的单相液体压力梯度更大217%至223%- 与R-134a相比，12%和更高，为198%至202%。碳氢化合物的平均蒸发压力梯度比R-12大168%至339%，比R-134a大138%至270%。最后，与R-12相比，平均冷凝压力梯度更大178%至308%，与R-134a相比更大164%至284%。研究结果可用于以碳氢化合物为制冷剂的空调系统换热器的设计。单位:双引文:研讨会，ASHRAE交易，第106卷，pt。2.

Pressure gradients for single-phase flows (both vapor and liquid) and two-phase flow during boiling and condensation are presented for propane (R-290), isobutane (R-600a), and a 50/50 mixture (by weight) of propane and isobutane. The pressure gradients are presented for smooth tubes based on stan-dard correlations available in the literature for pure refrigerants. The mass flux of the refrigerant is varied over a wide range typically encountered in residential, commercial, and automotive applications. Evaporation temperatures of 6.7°C (20°F) and 4.4°C (40°F) and condensation temperatures of 37.8°C (100°F) and 48.9°C (120°F) were used for this investigation. The pressure gradients for hydrocarbons R-290, R-600a, and the mixture of R-290/R-600a are compared with those for R-12 and R-134a. The REFPROP computer program developed by NIST was used to determine the thermodynamic properties for R-290, R-600a, and R-290/R-600a. The study shows that the pressure gradients for hydrocarbons are significantly higher than for both R-12 and R-134a. For the range of refrigerant temperatures and mass flux studied, single-phase vapor pressure gradients for hydrocarbons are greater by 153% to 374% in comparison to R-12 and are greater by 123% to 307% in comparison to R-134a. The single-phase liquid pressure gradients for hydrocarbons are greater by 217% to 223% in comparison to R-12 and are greater by 198% to 202% in comparison to R-134a. Average evaporation pressure gradients for hydrocarbons are greater by 168% to 339% in comparison to R-12 and are greater by 138% to 270% in comparison to R-134a. Finally, average condensing pressure gradients are greater by 178% to 308% in comparison to R-12 and are greater by 164% to 284% in comparison to R-134a. The results in this investigation can be used in the design of heat exchangers with hydrocarbons as the refrigerant for the air-conditioning systems.Units: Dual