One of the major challenges for a ship sailing in Arctic waters is ice aggregation. Atmospheric water or sea spray that comes into contact with the cold railing, equipment and superstructure deposits ice on the exposed surfaces. This ice can build up over time to such an extend, that the weight of the ice can severely impair the ships stability, even lead to capsizing. To prevent such accidents, the IMO Polar Code for ships operating in Arctic areas requires countermeasures against icing. Ulmatec Pyro has developed a “double pipe system” that makes use of waste heat, recovered from the ships propulsion and energy system.
The main objective of this research project has been to investigate the behavior of anti-icing and de-icing for pipe structures to provide design rules and operational guidelines for such systems.
Pipe systems have been studied using both numerical and experimental methods. First a simple 1D pipe system, simulating the steady heat transfer with a finite difference method, was implemented. The purpose of this model is was to be able to quickly study design variations. Next, a more advanced 3D axis-symmetric heat flow model was simulated, using a commercial transient finite element solver. The results of the advanced model was used to evaluate the simple model. Subsequently these simulation tools were used to support the design decisions for the experimental setup. To get the IMO approval for the double pipe system, the experiments were conducted at the site of the classification society. The experimental setup was used to validate the simulation model, and furthermore as a design verification lab for Ulmatec Pyro.
A comparison of the results between both numerical simulation models and experiments show a good correlation. In addition, the experiments provide a valuable insight into the icing- and anti-icing processes. Specifically, a better understanding of the complex ice melting process.