## 6 Conclusions  
In order to improve the performance and production efficiency of PCMS at an industrial scale, three novel impellers (PBPT, BCBT and BCPBT) were proposed in this paper. The performance of the original impeller (PBT) and three novel impellers were evaluated in a solid-liquid stirred tank utilizing the EE-KTGF approach. The numerical model was verified by a PIV experiment and the experimental data from [PERSON] et al. [25]. The flow field, trailing vortex, turbulent parameters, local axial solid concentration profile and cloud  
Figure 19: 3D solid volume fraction contour plots and cloud height for different impeller speeds. (**a**) 180 rpm, (**b**) 300 rpm, (**c**) 420 rpm, (**d**) 540 rpm.  
Figure 18: 3D sediment volume plot upon contour plots of solid volume fractions on a vertical diametrical plane for different impeller speeds. (**a**) \(N=180\) rpm, (**b**) \(N=300\) rpm, (**c**) \(N=420\) rpm, (**d**) \(N=540\) rpm.  
height were predicted. Furthermore, the effects of aperture parameters, impeller speed and liquid viscosity of BCPBT on solid-liquid mixing homogeneity were studied. The results of the current study can be summarized as follows:  
The novel impellers are able to generate high-speed jets in the process of rotation, which can not only reduce the size of the trailing vortex and the pressure difference of the impeller blade, but also enhance the velocity gradient and turbulence parameters in this manner to improve the solid-liquid suspension quality and reduce power consumption. Notably, the BCPBT can more effectively suspend solid particles, and the power consumption shows a decrease of approximately 17%, which is of great significance for the preparation processes of PCMs in refrigeration systems.  
Proper impeller structure parameters play an essential role in the solid-liquid mixing performance of a stirred tank. An aperture diameter of 8 mm and the aperture ratio of 13% are especially appropriate for the solid-liquid suspension process in this work. An appropriate selection of other design and structure parameters, such as the amplitude and wavelength of the bionic cut, impeller clearance and diameter will be addressed in the near future.  
The BCPBT facilitated the solid-liquid suspension for different viscosities of liquids, and increasing the impeller speed in a certain range can significantly promote the solid-liquid mixing. Moreover, the approach of opening holes and bionic cuts is also applicable to other types of impellers. The punched-bionic impeller, therefore, can be widely utilized for many chemical industry and energy applications, such as in the preparation processes of PCMs for solid-liquid mixing.  
Data curation, Z.G.; funding acquisition, S.Z.; investigation, D.X. and Q.Y.; project administration, S.Z.; methodology, W.Z.; validation, D.X. and Q.Y.; writing--original draft, W.Z.; writing--review and editing, Z.G. All authors have read and agreed to the published version of the manuscript.  
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: this work is supported by National Natural Science Foundation of China (Grant No. 51706203), the National Science and technology major special sub project (2019 zx06004001) and the Natural Science Foundation of Zhejiang Province, exploration project (Y, LY20E09004).  
Thanks to Zhejiang University of Technology for providing computing resources and technical support. The authors also appreciate all other scholars for their advice and assistance in improving this article.