Accession Number:

ADA305290

Title:

Development of Plastic Heat Exchangers for Ocean Thermal Energy Conversion.

Descriptive Note:

Final rept. Aug 76-Dec 78,

Corporate Author:

DSS ENGINEERS INC FORT LAUDERDALE FL

Personal Author(s):

Report Date:

1979-01-01

Pagination or Media Count:

141.0

Abstract:

Materials and processes were selected and design information was obtained for plastic ocean thermal energy conversion OTEC heat exchangers as the result of a program comprising five types of laboratory experiments. Tests to evaluate the chemical resistance of seven commercially available thermoplastics to sea water and several possible working fluids were conducted with emphasis placed on compatibility with ammonia. Environmental rupture tests involving exposure of stressed specimens to sea water or liquid ammonia indicated that the high density polyethylene HDPE is the best suited candidate and produced an extrapolated 100,000 hour failure stress of 1060 psi for HDPE. Long term durability tests of extruded HDPE plate-tube panel confirmed that plastic heat transfer surface is mechanically reliable in an OTEC environment. Thermal conductivity measurements of acetylene black filled HDPE indicated that conductivity may be increased by 50 with a 35 by weight filler loading. The permeability coefficient measured for liquid ammonia through HDPE was higher than previous estimates. Test showed that the rate can be significantly reduced by sulfonation of HDPE. A review of biofouling mechanisms revealed that the per- meable nature of the plastic heat exchanger surface may be used to control primary biofouling form formation by allowing incorporation of non-toxic organic repellents into the plastic. A preliminary design and fabrication development program suggests that construction of an ammonia condenser test unit is feasible using currently available materials and manufacturing techniques.

Subject Categories:

  • Air Conditioning, Heating, Lighting and Ventilating
  • Thermodynamics
  • Plastics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE