## 1 Introduction  
The icing phenomenon exists in many industries, such as aviation [1], electric power [2; 3; 4], energy storage [5; 6], meteorology [7; 8; 9], and other fields related to people's livelihood and infrastructure construction. In some areas, the presence of ice can be harmful. As a future energy and resource base, the polar region has an increasingly prominent strategic position and will become one of the key areas for all countries in the future. In order to ensure the normal navigation of gas turbine ships in the Arctic and Antarctic, it is necessary to study the icing phenomenon of ships in the marine environment. In the marine environment, the phenomenon of salt water freezing on the surface of ships often occurs. Various studies have shown that salinity has an obvious influence on the freezing time of droplets and it can greatly reduce the speed of the freezing peak. Currently, most of the studies on surface freezing have been concerned with the freezing phenomenon of pure water on a specific surface [10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]. Experimental methods and numerical simulation methods are usually used to study the freezing process of droplets. [PERSON] [29] investigated the freezing process of droplets on a cold superhydrophobic substrate. They observed a considerable delay in nucleation in saltwater compared to freshwater. [PERSON] [30] studied the behavior of droplets from the supercooled liquid phase to the liquid-solid phase and then to the solid phase on the basis of experimental studies. These three transformations are caused by various exchanges: heat transfer by conduction and convection and mass transfer by evaporation and sublimation. The phenomenon of supercooling was naturally observed in the experimental process and was considered in the modeling process. [PERSON] [31] investigated the effect of surface moisture on droplets impacting dry solid walls. The droplet kinematic characteristics under nine different surfaces and 12 impact velocities were analyzed with contact angles ranging from 48\({}^{\circ}\) to 166\({}^{\circ}\). It was found that when the Weber number was greater than 200, the surface contact angle had little influence on the spread coefficient because the inertia force was significantly greater than the capillary force. [PERSON] et al. [32] used an infrared thermal imager and high-speed camera to study the static freezing process of droplets. The test surface was a smooth silicon surface and a micro/nano silicon surface, and the test object was a 6-microliter static droplet. The influence of the temperature curve and surface contact angle on the freezing process of the droplet was studied. [PERSON] et al. [33] studied the freezing process of droplets under different wetting conditions. In their study, invasive and non-contact measurements were used to record the changes in the droplets' internal temperature during the freezing process to determine their cooling and phase transformation process. It was found that the freezing time of the droplets depended on the melting temperature and the surface moisture of the wall. A heat transfer simulation during freezing was carried out using a model based on enthalpy-porosity to understand the heat transfer in the freezing process. The droplet freezing stage was numerically analyzed and compared with the experimental results. The droplet freezing time was in good agreement with the experimental data. [PERSON] et al. [34] used the lattice Boltzmann method (LBM) to establish a model and studied the solidification process of water droplets on a cold plate using velocity and temperature distribution functions. Using the LBM model, the solidification process is simulated in the form of temperature and solid phase changes of water droplets on a cold plate. The solid phase morphology during the solidification process is predicted. In addition, the LBM model is also used to study the frosting process preliminarily. The numerical results are in good agreement with the experimental data.