<p>Ocean wave energy conversion plants that use hydraulic power take-offs (PTOs) to convert wave induced motion to electricity or pressurized seawater for reverse osmosis desalination might be configured so that the working fluid is piped from the wave energy converter (WEC) located offshore to equipment located onshore. These plants would have pipelines that are in the range of several hundred to a few thousand meters long. With the pulsatile flow generated by the WEC having a period in the range of 3 to 12 seconds, the wavelengths of excited pressure waves approach the length of the pipelines. Furthermore, the use of switch-mode architectures for these PTOs would introduce even higher frequency excitations to the pipelines. By the standards for modeling pipelines presented in the literature, the system models for these plants should include distributed parameter models of the pipeline dynamics. This paper presents a contextualize scheme to test the significance of pipeline dynamics for wave energy conversion plants. The analysis is carried out using a simplified representation of a hydraulic PTO for wave energy conversion. Different types of pipeline models are used within the system model and important metrics are compared from simulations. These results are used to show the degree of modeling fidelity that is needed to adequately predict design metrics. The pipeline models tested include 1) a short line model that includes resistive effects only, 2) a medium line model that includes inertial and capacitive effects for a single pipeline segment, 3) a long line, lumped parameter model that uses repeated, lumped parameter line segments to approach a distributed pipeline, 4) a simple methods of characteristics solution to the one-dimensional momentum and continuity equations, and 5) a discrete free-gas cavity model augmenting the simple method of characteristic pipeline model. The results suggest a more nuanced set of recommendations for modeling pipelines in these systems than is presented in literature that depends on the context in which the pipelines are placed.</p>

Pipeline Model Fidelity for Wave Energy System Models

Paper Proceedings: https://asmedigitalcollection.asme.org/FPST/FPMC2021/volume/85239

2021 ASME/BATH Symposium on Fluid Power and Motion Control (FPMC2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.