This paper presents an experimental investigation of condensation heat transfer of alternative refrigerant R-134a flowing inside a helical pipe with cooling water through the concentric annular passage in a counter-flow direction. The experiments were conducted with the helix axis of the test section in horizontal, vertical, and inclined orientation directions, respectively. The mass flow flux for R-134a ranges from 100 to 400kg/m2s and the Reynolds number of cooling water ranges from 1500 to 10000. The results demonstrate the orientation of helical pipe has a significant effect on both refrigerant-side heat transfer and overall heat transfer coefficients.

This article presents an experimental investigation on condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturation temperatures(35℃, 40℃ and 45℃) with the refrigerant mass flux varying from 100kg/m-s to 400kg/m-s and the vapor quality ranging from 0.1 to 0.8. The effects of vapor quality and mass flux of R-134a on the condensation heat transfer coefficient were investigated. The results indicate that the condensation heat transfer coefficients of the helical section are 4%-13.8% higher than that of the straight section. The experimental results were compared with the data available in literature for helical and straight pipes.

制冷剂R2134a 在螺旋管内的凝结换热和压力降特性数据对于制冷空调和热泵等系统的设计改造及运行都具有重要的理论意义和工程应用价值。本文对R2134a 在螺旋环形通道内的凝结换热和压力降特性进行了实验研究,得到了平均的凝结换热系数和压力降特性的实验数据,并与文献报导的R2134a 在直管和螺旋管内凝结换热的实验结果进行了比较, 所得实验数据可望为新型螺旋管换热器的开发设计和工程应用提供参考数据。

对替代制冷剂R-134a在螺旋管内的对流凝结换热特性进行了实验研究。在制冷剂R-134a的质量流量变化范围为100～400kg/（m2s）和冷却水的平均温度分别为12℃和22℃的条件下, 实验得到了在三种不同放置方式螺旋管内（ 水平, 垂直和倾斜） R-134a的对流凝结换热特性数据。实验结果表明, 螺旋管的不同放置方式对R-134a在螺旋管内的凝结换热特性具有重要的影响。通过与已有研究结果的比较, 简要分析了螺旋管不同放置方式对R-134a对流凝结换热特性的影响机理。

发展了一种基于MATTAB和VB软件包的质子交换膜燃料电池（PEMFC）特性参数仿真实验软件。主要介绍了仿真软件的建模、设计方法和用户界面构成。仿真实验结果表明，该仿真软件可以满足PEMFC特性参数仿真实验教学的要求，为PEMFC特性参数的实验研究和实验教学与演示提供了一个有效工具。