Mechanical Analysis of Free-Standing Cold-Water Pipe for Ocean Thermal Energy Conversion

As a controllable power generation method requiring no energy storage, Ocean Thermal Energy Conversion (OTEC) technology demonstrates characteristics of abundant reserves, low pollution, and round-the-clock stable operation. The free-standing cold-water pipe (CWP) in the system withstands various complex loads during operation, posing potential failure risks. To reveal the deformation and stress mechanisms of OTEC CWPs, this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths. Based on the Euler-Bernoulli beam model, a quasi-static load calculation model for OTEC CWPs was established. The governing equations were discretized using the finite difference method, and matrix equations were solved to analyze bending deformation, bending moments, and surface stresses at discrete points along the pipe. Results indicate that water depths within 50 m represent a critical zone where wave particle velocity, acceleration, and wave loads exhibit significant variations in harmonic patterns, while beyond 50 m depth wave loads decrease linearly. Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement. Considering the effect of clump weights, the maximum lateral displacement occurs at 600–800 m below sea level. Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.