Heat transfer enhancement in cold plates with wavy channels via free-shape modeling and optimization

The objective of this study is to improve heat transfer performance of cold plates with wavy channels typically used in Battery Thermal Management Systems (BTMSs). The means of enhanced design flexibility based on parametric modeling allows for the free construction of wavy geometry in terms of amplitudes, wavelengths, waveforms, and cross-sections. The fixed dimensions are "liberated" into these four degrees of freedom, which helps to find the optimized wavy structures with the superior cooling performance. Based on the proposed freeshape modeling framework, the Horizontal Wavy Channel (HWC) and Radial Wavy Channel (RWC) are constructed, and these single channels can be considered as the basic structure of cold plates. One of the most popular evolutionary algorithms, NSGA-II, is utilized to optimize these two types of channels. The average temperature (overall thermal performance) and root mean square temperature (temperature uniformity) of top and bottom surfaces of cold plates are specified as the objective functions. In addition, to better verify the validity of the proposed method, empirical-based uniform HWC (UHWC) and RWC (URWC) are given as further comparisons. Based on the obtained Pareto front and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, when the weight coefficients of the two thermal performance indicators are set to 0.5:0.5, the best compromised solutions are obtained: VHWC-22 for HWC and VRWC-30 for RWC. The results further show that the ranking of excellent overall thermal performance is VHWC-22 > URWC >:::-.1 VRWC-30 > UHWC, while the ranking of excellent temperature uniformity is VRWC-30 > VHWC-22 > URWC > UHWC. Obviously, the variable wavy channels are generally superior the uniform wavy channels in terms of thermal performance. This work provides a guideline for the design of wave structures that can be used not only in cold plates but also in heat sink with fins, heat exchangers, and other components with wave structures.