Numerical analysis of conjugate heat transfer for various ice-ball shapes

In this study, numerical simulations were conducted for conjugate heat transfer around ice balls in an encapsulated ice thermal storage system. Four shapes of ice balls were modeled; the default one was a sphere, and the other three shapes were designed to enhance convective heat transfer through the ball surface. The flow around the ball was laminar, for which the Reynolds number was 300, and both forced and natural convections inside and outside the balls were considered. The simulations revealed that the magnitude of convective heat transfer for the different shapes decreased in the following order: bone, dimple, hole, and sphere. For the entire simulation, the maximum difference in the average temperatures of water inside the capsules was found to be 0.9°C. Therefore, it can be said that the effect of ice-ball shape on the performance of the ice thermal storage system is significant, considering that more than 0.3 million balls are used in this system.