Multiple optimization design on gradient porosity of copper foam in phase change materials based on genetic algorithm

Abstract

Copper foam with gradient porosity has been incorporated into phase change materials (PCMs) to improve their thermal performance by improving the non-uniform melting process within a square unit. However, there are currently limited design principles and methods for arranging the gradient porosity of copper foam. This paper introduces a novel multiple optimization design method for gradient porosity of copper foam, which utilizes a combination of the response surface methodology and genetic algorithm. First, the gradient design objective prototype is established by varying the gradient design direction and porosity of the copper foam. Then, the response relationship between melting time and porosity is derived using the central composite design method. Subsequently, the distribution of copper foam with a porosity ranging from 0.75 to 0.95 is optimized with the primary goal of minimizing the melting time. The results indicate that PCM with gradient copper foam exhibits a 9.11 % reduction in melting time compared to PCM with uniform copper foam. In addition, the secondary objective of the multiple optimization design is to minimize the weight of the phase change unit. The results reveal that both the melting time and weight of the phase change unit are reduced by 4.63 % and 9.57 %, respectively. This multiple optimization method provides principles and methods for improving the thermal performance of PCM using gradient copper foam. The optimized gradient structure meets the requirements for weight reduction and efficiency improvement in composite PCMs for latent heat thermal energy storage systems.