## 2 Basic Analysis of Prediction Models and Model Verification
### Screening of Coolants for Model Verification  
Some studies have shown that the reliability of electronic devices is exponentially related to the operating temperature [48] and the reliability of CPU decreases by about 25% for every 1 \({}^{\circ}\)C increase when the operating temperature is in the range of 70-80 \({}^{\circ}\)C [49]. Therefore, the boiling point of the coolant is an important basis for screening the coolant suitable for two-phase immersion cooling systems. If the boiling point is too high, the temperature of the electronics will be close to or exceed the optimal working temperature zone when boiling begins, resulting in the performance degradation of the electronics. Regarding mineral oils commonly used in liquid immersion cooling systems, despite their excellent performance, they are only suitable for single-phase immersion cooling systems due to their high boiling points (up to several hundred degrees Celsius), such as GRC's ElectroSafe and ElectroSafe Plus [50; 51]. Another kind of commonly used coolant is electronic fluoride liquid with good insulating performance. The boiling points of some electronic fluoride liquids are slightly higher than room temperature (about 45\(\sim\)60 \({}^{\circ}\)C) and they are easy to boil within the operating temperature of electronics. Thus, electronic fluoride liquids with boiling points (about 45\(\sim\)60 \({}^{\circ}\)C) slightly higher than room temperature are very popular in two-phase immersion cooling systems. At present, three kinds of commonly used electronic fluoride liquids in two-phase liquid immersion cooling systems are perfluorohexane (FC-72), perfluorohexanone (Novec 649) and nonafluorobutyl methyl ether (HFE-7100) [15; 52; 53; 54; 55; 56; 57], and the key thermophysical properties of these electronic fluoride liquids have been widely studied by experimentation, as shown in Table 1. Therefore, FC-72, Novec 649 and HFE-7100 were selected to evaluate the accuracy and practicality of prediction models.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Reference** & **Therophysical Properties** &
\begin{tabular}{c} **Temperature** \\ **Range** \\ \end{tabular} & **Pressure Range** & **Measurement Method or Instrument** \\ \hline \multicolumn{5}{c}{FC-72} \\ [PERSON] et al. [58] & Density & 273–323 K & & Pycnometer \\  & Saturated vapor Pressure & 284–343 K & & \\  & Surface tension & 283–323 K & & Capillary ascending method \\  & Viscosity & 273–323 K & & Ubbelohde viscometer \\ [PERSON] et al. [59] & Saturated vapor Pressure & 303–330 K & & Static method \\  & Density & 288–318 K & Atmospheric & \\  & & Density & 288–318 K & pressure, & Expansion bottle \\ [PERSON] et al. [60] & Saturated vapor pressure & 288–308 K & & Static method \\  & Density & 288–298 K & & Vibrating tube method \\ [PERSON] et al. [61] & Viscosity & 298–318 K & & Atmospheric \\  & & pressure & Ubbelohde viscometer \\ [PERSON] et al. [62] & Surface tension & 283–308 K & & Surface pressure gauge \\ [PERSON] [63] & Density & 233–253 K & & Pycnometer method \\  & Viscosity & 233–253 K & & Ubbelohde viscometer \\  & Specific heat capacity & 233–253 K & & Differential scanning calorimeter \\ \hline \end{tabular}
\end{table}
Table 1: Studies on the thermophysical properties of FC-72, Novec 649 and HFE-7100.  
Prediction of Thermophysical Properties of Electronic Fluoride Liquids for Two-Phase Liquid Immersion Cooling Systems