Testing of a shell-less, folded-aluminum-tube heat exchanger core unit as an evaporator and a condenser
A full-scale portion (core unit of 1-MW/sub t/ size) of a shelless, folded-aluminum-tube heat exchanger, conceived by JHU/APL as an integral part of an Ocean Thermal Energy Conversion (OTEC) power system, was tested first as an evaporator and then as a condenser. The overall heat transfer coefficients (U's) were 480 and 435 Btu/hr-ft/sup 2/-/sup 0/F for the evaporator and condenser, respectively, at the conditions yielding the optimal trade-off between the U's and the ammonia pumping power for a full-scale unit. In both modes it operated stably with essentially equal ammonia distribution among the tubes. The water-side pressure drop was as predicted for the optimal water velocity of 2.5 ft/s through the minimum gaps between tubes in the staggered tube array. The evaporator ammonia-side pressure drop was lower than predicted; however, because of the stratified flow that apparently exists, the condenser ammonia pressure drop was higher than predicted. The computer simulation for closed-cycle power system performance was revised to reflect the test results. Full-scale heat exchanger modules designed for 5 MW/sub e/ net power at an ocean water temperture difference of 42/sup 0/F would have 69 vertical rows of seven nested, folded tubes each -1932 tubes total of 3-in.-OD Alclad (7072) 3004 aluminum alloy, each folded into 25 horizontal passes. These heat exchangers, cleanable by vertical translation of ultrasonic cleaning devices between tube rows, offer a viable, low-cost option for OTEC use. Prior work on this concept is summarized, and recommendations for at-sea tests are presented.
- Research Organization:
- Johns Hopkins Univ., Laurel, MD (USA). Applied Physics Lab.
- DOE Contract Number:
- AI01-77ET20342
- OSTI ID:
- 5162013
- Report Number(s):
- JHU/APL-AEO-81-122; ON: DE84005601
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140800* -- Solar Energy-- Ocean Energy Systems
CLOSED-CYCLE SYSTEMS
COMPUTERIZED SIMULATION
CONDENSERS
ENERGY TRANSFER
EVAPORATORS
HEAT EXCHANGERS
HEAT TRANSFER
OCEAN THERMAL POWER PLANTS
PERFORMANCE TESTING
POWER PLANTS
PRESSURE DROP
SIMULATION
SOLAR POWER PLANTS
TESTING
THERMAL POWER PLANTS