At-Sea Test of a Large Scale OTEC Pipe

Abstract

An important goal in the Ocean Thermal Energy Conversion (OTEC) development program is to demonstrate the viability of the present technology to satisfactorily design, fabricate and operate a cold water pipe (CWP) in an ocean environment. The cold water pipe, named for its use in conveying cold water from ocean depths, is the most critical element in any OTEC design. In order to provide engineering information concerning the many risk areas associated with the CWP, a significant size fiberglass reinforced plastic (FRP) pipe was designed, fabricated and deployed. The test article, a scaled representation of a 40 megawatt sized CWP, was 8 feet in diameter and 400 feet long and had a sandwich wall construction of FRP facesheets over a syntactic foam core. The CWP was fabricated in sections on the United States mainland and the sections joined in Honolulu, Hawaii. Instrumentation including strain gages, accelerometers and differential pressure transducers was installed on the CWP to provide measurement data. After attachment to a floating platform, the CWP was towed to sea and moored for a three week field test in April 1983. A major goal of this experiment is to provide data toward a better understanding of the pipe dynamics and to provide measurements for validating the analytical models used in predicting the CWP/ platform loads, dynamic responses and stress levels. During the experiment, 30 hours of data were collected from 100 channels at a 1 Hz rate by the data acquisition system. Preliminary analysis of the time series records of the environmental loading and structural response data has indicated high quality data return. All information available from the testing activities at this time indicates that the test objectives were successfully met.