After several months of immersion in seawater, the first PVC tube in a series of three has just been taken out for an innovative experiment. The aim is to characterise the thermal resistance of biofouling that develops on submerged surfaces, particularly on the dynamic electricity export cables of ORE systems.
The first step is to identify and quantify the living organisms that have colonised the outside of the tubes. To do so, a series of photos, as well as direct measurements of thickness, total diameter and perimeter are taken following a protocol that allows the studied object to be gridded.
Once transported to the Ifremer test platform, each tube is immersed in a controlled environment to undergo a series of tests. The objective is to measure the thermal exchanges between a flow of fresh water heated to 45°C circulating inside the colonised tube and a flow of sea water circulating outside the tube. This device will enable the range of heat transfer coefficients of biofouling to be determined. The results obtained will be used to update the methodology for calculating umbilical fatigue, taking into account the heterogeneous distribution of the biofouling.
Photo credit: France Energies Marines