Subsea Pipeline Hybrid Thermal Insulation with Phase Change Material and Aerogel – Analysis and Experiments

Abstract

This study investigates a hybrid thermal insulation system for subsea pipelines. The insulation system combines a traditional insulation material, Aerogel, with a phase change material (PCM), paraffin wax, for thermal energy storage to better regulate fluid temperatures and improve flow assurance for subsea pipelines. This paper first discusses flow assurance challenges, including hydrate formation and wax deposition, for subsea pipelines in the harsh environment. Different mitigation methods are then reviewed, particularly the thermal insulation methods to prevent heat loss from the pipelines. Analytical and numerical heat transfer analyses show that the hybrid thermal insulation system can be designed with proper thickness of the Aerogel and PCM layer for heat loss prevention and cool down time extension during a flow line shut-in operation. A lab-scale prototype is designed, fabricated and experimentally tested on a flow loop. Measured temperatures provide useful data to understand the transient heat transfer in the hybrid insulation system, as well as lab demonstration of the good insulation performance, with the cool down period extended by more than three times than an Aerogel only case.