In situ heat exchanger tube fouling thickness measurements using ultrasonics. Final report on a laboratory feasibility study

Technical Report · Mon Sep 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/6720773· OSTI ID:6720773

Hirshman, J; Munier, R S.C.

The growth of fouling layers on heat exchanger surfaces and the corrosion of heat exchanger materials exposed to seawater have been recognized since the beginning of OTEC research as basic problems which could render the concept uneconomical. Consequently, a significant effort has been directed toward predicting, measuring, identifying, explaining and solving potential biofouling and corrosion phenomena. To address this problem, the feasibility of establishing a practical microacoustic technique to measure fouling film thickness in situ on typical OTEC heat exchanger tasks was studied. Seven techniques were studied for this application, including velocity measurements, acoustic diffraction, acoustic interferometer, Doppler flow velocity, pulse echo, critical angle, and surface (shear) wave effects. Of these, the latter five were laboratory tested using conventional microacoustic system components in various configuratons. Only the pulse echo technique yielded promising results. On fouled aluminum plates, thin film layers of 40 ..mu..m and greater were measured using a focused 30 MHz ceramic transducer operated at 25 MHz; this represents a resolution of about 2/3 wavelength. Measurements made on the inside of fouled 1'' aluminum pipes yielded film thicknesses of 75 to 125 ..mu..m. The thinnest layer resolved was approximately 1-1/4 wavelength. The resolution of slime layer thicknesses in the magnitudes of OTEC interest (5 to 30 ..mu..m) using pulse echo microacoustics will require transducer development. In particular, a higher operating frequency (150 to 200 MHz) and advanced material construction is recommended for further research.

• Research Organization: Army Nuclear Agency, Fort Bliss, TX (USA); Tracor Marine, Port Everglades, FL (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6720773
• Report Number(s): ANL/OTEC-BCM-014
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140800* -- Solar Energy-- Ocean Energy Systems
ACOUSTIC TESTING
ALUMINIUM
BACTERIA
BIOLOGICAL FOULING
CHEMICAL REACTIONS
CONVERSION
CORROSION
DEPOSITS
DIMENSIONS
ELEMENTS
ENERGY CONVERSION
ENERGY TRANSFER
FOULING
HEAT EXCHANGERS
HEAT TRANSFER
HYDROGEN COMPOUNDS
INTERFEROMETRY
LAYERS
MATERIALS TESTING
MEASURING METHODS
METALS
MICROORGANISMS
NONDESTRUCTIVE TESTING
OCEAN THERMAL ENERGY CONVERSION
OXYGEN COMPOUNDS
PIPES
SEAWATER
SOLAR ENERGY CONVERSION
TESTING
THICKNESS
TUBES
ULTRASONIC TESTING
WATER