Flexural Capacity Evaluation of OTEC Piping System: Finite Element Analysis and Governing Formula

Abstract

The application of renewable energy plays a crucial role in advancing sustainable development, with one such source being ocean thermal energy conversion (OTEC). OTEC systems harness the temperature difference between sea surface water and deep seawater to generate electricity. A key component of the OTEC system is the piping network, which, despite its importance, has not been extensively studied. Thus, the current study aims to investigate how geometric variations and material properties affect pipe strength and to develop a predictive formula for estimating the pipe’s bending capacity. The analysis uses the finite element method (FEM), starting with a validation phase against previous studies to ensure the accuracy of the scenario and test module settings. A simulation case study is then conducted, focusing on pipe bending by varying pipe geometry and material yield stress. The results of the variation analysis show that each parameter substantially impacts pipe performance. Specifically, a smaller length-to-diameter (L/D) ratio results in a stiffer pipe, as does a smaller diameter-to-thickness (D/t) ratio. In addition, materials with low yield strength deform easily. Using the test data, a nonlinear regression model was developed to generate a predictive formula for estimating the ultimate flexural capacity of the pipe. The validation results of this formula show that the developed equation is highly accurate and outperforms existing empirical formulas. This study provides valuable insights for designing efficient and optimized OTEC piping systems, offering a fast and accurate estimation tool.

Keywords

Renewable energy structure / Cylindrical shell / Ultimate bending moment / Nonlinear regression / Governing equation

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