Title: Enhanced Heat Transfer by a Spiral Spring Augmentive Device Inside a Round Tube
text: The use of augmentive devices in round tubes to promote heat transfer has been known to the industry for some time. Early work has shown that the improvement in heat transfer in a round tube is considerably greater with an augmentive device when in the heating mode than in the cooling mode. As a result, the bulk of the effort, thus far, appears to be in the heating mode. This work is set to prove that the augmentive devices are as efficient in the cooling mode as in the heating mode. This work also opens the doors to many applications where space and cooling equipment size are a factors to be considered during the design of systems. This study utilizes a spiral spring augmentive device in four wire diameters and in four turns per inch for each wire diameter in a nominal 0.375 diameter copper tube. The coil diameter of the augmentive device was sized to fit inside the tube with a minimum clearance.