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U.S. Department of Energy
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Experimental study of ammonia condensation on vertical fluted tubes. [For OTEC plants]

Conference ·
OSTI ID:7043337
Experiments were run to determine heat transfer performance of single vertical tubes with ammonia condensing on the outside. The four test tubes (aluminum) were of 1-in. nominal diameter and 4-ft length with 0 (smooth), 24, 48, and 60 external flutes. The condensing heat transfer coefficients are reported as composite coefficients that include the resistance of both the condensing side and the tube wall. The composite condensing coefficients ranged from 720 to 9600 Btu/hr x ft/sup 2/ x /sup 0/F over a heat flux range of 1600 to 16,000 Btu/hr x ft/sup 2/. All parameters were based on total condensing surface area. The data show that, for a given heat flux, a fluted tube can increase condensing coefficients up to 7.2 times smooth tube values. Corresponding condensing temperature differences (composite) ranged from 0.3 to 23/sup 0/F in the experiments; and the data show that, for a given condensing temperature difference, a fluted tube can accommodate heat loads up to 5.4 times the smooth tube values. Conversely, for a given heat load, a smooth tube requires condensing temperature differences up to 9.7 times the fluted tube values.
Research Organization:
Oak Ridge National Lab., Tenn. (USA)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
7043337
Report Number(s):
CONF-780408-2
Country of Publication:
United States
Language:
English