CS-4 Comparison of Condensation of Steam on Plain and Spirally Grooved Tubes in a Baffled Shell-and-Tube Condenser
This report contains the results of two studies:
Phelps Dodge
This study compares spirally grooved tubes of two different configurations, manufactured by the Phelps Dodge Copper Corporation, with plain tubes for condensation of steam in multitube baffled shell-and-tube condensers. Water was used as the coolant.
In general, the heat transfer performance of the spirally grooved tubes was superior to that of the plain tubes. Overall heat transfer coefficients averaged from around 10 to 30 percent higher for the spirally grooved tubes, depending on conditions. More improvement was noticed for the tubeside no-phase-change heat transfer coefficient than for the shellside condensing heat transfer coefficient.
Increase in tubeside heat transfer rates was accompanied by an increase in pressure drop. The tube configuration with shallower grooves and shorter groove pitch apparently produced a more efficient conversion of pressure drop to heat transfer than the other spiral tube, and gave in general the best performance of the three tube types tested.
Turbotec Tubes
This study compares spirally grooved tubes with a deep groove configuration, manufactured by the Turbotec Corporation, with plain tubes for condensation of steam in multitube baffled shell-and-tube condensers. Water was used as the coolant. In general, the heat transfer performance of the spirally grooved tubes was much higher than that of the plain tubes. Overall heat transfer coefficients averaged around 120 percent higher for the spirally grooved tubes when corrected for difference in tubewall resistance. About the same amount of improvement was noticed for the tubeside no-phase-change heat transfer coefficient and for the shellside condensing heat transfer coefficient.
Increase in tubeside heat transfer rates was accompanied by a severe increase in pressure drop. Conversion of pressure drop to heat transfer has been shown in earlier studies to be very inefficient for deep grooved tubes, relative to plain tubes. However, the tube should find high utilization in applications in which tubeside pressure drop is not a limiting condition, but requirements are for the smallest possible heat transfer area for a given set of process conditions.
Shellside pressure drop of the condensing vapors was low and was not significantly increased over that for a plain tube, for this particular baffle arrangement. Shellside condensation heat transfer enhancement was believed due to promotion of transition of the condensate film to the turbulent retime, and improved drainage.