通常的做法是，冷水机组和热交换器的设计不在过渡区内运行。这主要是由于该地区的混乱行为以及信息匮乏。然而，由于设计限制或运行条件的变化，交换器通常被迫在该区域运行。这对于增强管来说更糟糕，因为该区域内可用的信息要少得多。众所周知，入口对转换发生的位置有影响，增加了可用信息的痛苦。因此，本研究的目的是获得光滑和强化管内流动过渡区的传热和摩擦系数数据，并从这些结果中得出关联式。 关于过渡的开始，还研究了不同入口、管径和增强管的使用。从直径为5/8英寸（15.88毫米）和3/4英寸（19.02毫米）的六种不同类型的管中获得了传热和压降数据。低翅片增强管，翅片高径比为0.4，螺旋角为18°？27岁？进行了调查。通过管内热交换器获得传热，冷却水和水-乙二醇混合物作为试验流体。雷诺数在1000到20000之间，普朗特数在4到30之间。传热系数和摩擦系数的不确定性平均分别低于2.5%和10%。绝热摩擦系数结果表明，不同入口的使用影响了过渡的开始。 入口轮廓越平滑，过渡延迟的时间就越多。增加管径的效果在转变过程中有轻微的延迟。强化管导致在较低雷诺数下发生转变，这是由翅片高度而非螺旋角引起的。传热结果表明，在相同的雷诺数下，所有不同的入口和强化管都发生了相变。这是由于二次流力影响了不断增长的水动力边界层。这些二次流力还影响层流传热和非绝热摩擦系数，这两个参数都较高。湍流强化管的传热效果高于光滑管，螺旋角最大的管的传热效果增加最大。 水-乙二醇混合物没有显示出这些趋势，对于不同的入口配置，在不同的雷诺数下发生了转变。这表明，二次流不像水那样占主导地位。建立了所有管道及其入口的相关性，并预测所有数据的平均值在3%以内。单位:双

It is common practice to design water chiller units and heat exchangers in such a way that they do not operate within the transition region. This is mainly due to the perceived chaotic behaviour as well as the paucity of information in this region. Due to design constraints or change of operating conditions, however, exchangers are often forced to operate in this region. This is even worse for enhanced tubes as much less information within this region is available. It is also well known that the entrance has an influence on where transition occurs, adding to the woes of available information.The purpose of this study is thus to obtain heat transfer and friction factor data in the transition region of flow inside smooth and enhanced tubes and to develop correlations from these results. The use of different inlets, tube diameters and enhanced tubes was also investigated with regards to the commencement of transition.Heat transfer and pressure drop data were obtained from six different types of tubes with diameters of 5/8” (15.88 mm) and 3/4” (19.02 mm). Low fin enhanced tubes with a fin height to diameter ratio of 0.4 and helix angles of 18? and 27? were investigated. Heat transfer was obtained by means of an in-tube heat exchanger with the cooling of water and water-glycol mixture being the test fluids. Reynolds numbers ranged between 1 000 and 20 000 while Prandtl numbers were in the order of 4 to 30. Uncertainties in heat transfer coefficient and friction factors were on average below 2.5% and 10% respectively.Adiabatic friction factor results showed that the use of different inlets influenced the commencement of transition. The smoother the inlet profile the more transition was delayed. The effect of increasing tube diameters had a slight delay in transition. Enhanced tubes caused transition to occur at lower Reynolds numbers which was accounted for by the fin height and not the helix angle. Heat transfer results showed that transition occurred at the same Reynolds numbers for all the different inlets and enhanced tubes with the water. This was attributed to the secondary flow forces influencing the growing hydrodynamic boundary layer. These secondary flow forces also influenced the laminar heat transfer and diabatic friction factors with both these parameters being higher. Turbulent enhanced tube heat transfer results were higher than those of the smooth tube, with the tube with the greatest helix angle showing the greatest increase. The water-glycol mixture did not show these trends, with transition occurring at different Reynolds number for the different inlet configurations. This showed that secondary flows were not as dominant as for those for water. Correlations were developed for all the tubes and their inlets and predicted all the data on average to within 3%.Units: Dual