# Simulation Study on Nanofluid Heat Transfer in Immersion Liquid-Cooled Server
## 3 Data Processing and Analysis  
### Analysis of the Effects of Nanofluid Categories on Flow Heat Transfer  
#### 3.1.1 Core Component Temperature Analysis  
A temperature cloud map of the liquid-cooled server core components when FC-40 and Cu-FC40, CuO-FC40, Al-FC40, Al\({}_{2}\)O\({}_{3}\)-FC40, TiO\({}_{2}\)-FC40, the five types of nanofluid, are used as cooling media is shown in Figure 3. It can be seen from the figure that the temperature distribution of the core element is close to that of the core element under the flowing heat transfer state of each type of coolant, but the difference lies in the temperature interval values. With five types of nanofluid, the core element temperature range is roughly 324 K-367 K, while with coolant base fluid FC-40, the core element temperature range is roughly 326 K-372 K; the temperature range is reduced by 6.5%. In the flowing heat transfer state of nanofluid, the base fluid has greater thermal conductivity compared to the base fluid, which can cool the server core components to a lower temperature faster in the heat transfer process.  
The flow heat transfer effects of FC-40 and of the five types of nano-coolant on reference indicators such as GPU surface temperature, heat sink surface temperature, overall server maximum temperature, and server outlet maximum temperature are shown in Figures 4-7.  
Figure 3: Temperature cloud map of server core components under various types of coolant flow and heat exchange: (**a**) FC–40; (**b**) Cu–FC40; (**c**) Cu–FC40; (**d**) Al–FC40; (**e**) Al\({}_{2}\)O\({}_{3}\)–FC40; (**f**) TiO\({}_{2}\)–FC40.  
Figure 4: GPU surface temperature under various coolant flow and heat transfer conditions.  
Figure 5: Surface temperature of chip heat sink under various types of coolant flow and heat transfer.  
Figure 6: Maximum temperature of the overall server under various types of coolant flow and heat exchange.  
Figure 7: Maximum temperature of server outlet under various types of coolant flow and heat exchange.  
The diagram shows that, considering the coolant base fluid FC-40 flow heat exchange as the reference base, the highest GPU temperature ranking is Al-FC40 > TiO2-FC40 > Al2O3-FC40 > CuO-FC40 > Cu-FC40; the lowest GPU temperature ranking is Al-FC40 < Cu-FC40 < CuO-FC40 < TiO2-FC40 < Al2O3-FC40; the highest temperature ranking of the heat sink is Al-FC40 > TiO2-FC40 > Al2O3-FC40 > CuO-FC40 > Cu-FC40; the lowest temperature ranking of the heat sink is Cu-FC40 < CuO-FC40 < Al2O3-FC40 < TiO2-FC40 < Al-FC40; the overall highest temperature of the server is ranked as TiO2-FC40 > Al-FC40 > Al2O3-FC40 > CuO-FC40 > Cu-FC40; and the temperature of the server outlet is ranked as Al-FC40 > TiO2-FC40 > Al2O3-FC40 > Cu-FC40 > CuO-FC40. Compared to FC-40, the five types of nanofluid on the performance of the flow heat transfer in the liquid-cooled server is better, which shows that the surface temperature of the core element is lower and the temperature of the server outlet is higher, indicating that the nanofluid can take away more heat from the core element of the server. Among them, the Al-FC40 nanofluid has better heat transfer performance compared with the other four types of nanofluid, which shows that the lowest temperature of the GPU surface is 326.5 K; the lowest temperature of chip heat sink surface is 347.8 K; the highest temperature of the server as a whole is 392.4 K; and the temperature of the liquid outlet is 385.6 K.