# The Study of Novel Self-Rewetting Fluid Application to Loop Heat Pipe
## 3 Results and Discussion
### LHP Heat Performance  
To investigate the SRF in LHP, the dry-out was delayed, and the performance was enhanced by the Marangoni effect.  
From Figure 8, it was found that the operating temperatures of all three working fluids increased as the thermal load increased. When increasing the thermal load, the slope of the evaporator wall temperature increase is the largest for water, followed by the butanol 6% aqueous solution, and the smallest is the 2-butanol 20% aqueous solution. This also shows that the overall operating temperature of the 2-butanol 20% aqueous solution is lower than the other two working fluids at different heat loads, which symbolizes that the application of the 2-butanol 20% aqueous solution to LHP has better heat transfer performance, and not only lower thermal resistance, but also lower operating temperature, which effectively improves the overall performance. The heat load of the 2-butanol 20% aqueous solution was operated up to 900 W. Compared with water and butanol, the drying phenomenon occurred at 250 and 650 W, respectively. In comparison with the results of Wu [11] (water and butanol 6%) whose performance was based on the operating temperature of 170 \({}^{\circ}\)C, the performance of water was 250 W and the performance of the butanol 6% aqueous solution was 600 W, which is consistent with the results of this paper. The performance of the 2-butanol 20% aqueous solution was about 2.4 times higher than that of water at 170 \({}^{\circ}\)C. The performance of the 2-butanol 20% aqueous solution was about 30% higher than that of Butanol 6% aqueous solution.  
The relationship between the thermal resistance and heat load is shown in Figure 9. According to the thermal resistance change with heat load, 200 W is used as the cut-off point in the graph. In the part of the area where the heat load is less than 200 W, there is a characteristic that the thermal resistance decreases with the heat load, which is called the variable thermal resistance area. Therefore, the diagram clearly distinguishes between A and B thermal resistance characteristics, which is a typical feature of LHP. Figure 9 shows that the thermal resistance of the fluid is highest at lower heat load before the LHP starts smoothly. After the heat load increases, the thermal resistance decreases until about 200 W enters the B region, where the heat load increases, but the thermal resistance of the system does not change much. The minimum thermal resistance of LHP with the 2-butanol 20% aqueous solution and water is 0.25 \({}^{\circ}\)C/W. In LHP operation with the 2-butanol 20% aqueous solution, the minimum total thermal resistance is about 0.16 \({}^{\circ}\)C/W. The minimum thermal resistance of the butanol 6% aqueous solution and water is 0.25 \({}^{\circ}\)C/W and 0.624 \({}^{\circ}\)C/W,  
Figure 8: Evaporator temperature as a function of heat load for three different test samples [10].  
respectively. In addition, Figure 8 shows that the operating temperature of LHP with the 2-butanol 20% aqueous solution is always lower than that of LHP with butanol and water. The operating temperature of LHP with the 2-butanol 20% aqueous solution is always lower than that with butanol and water. The maximum heat load in Figure 9 is 900 W for the 2-butanol 20% aqueous solution, 650 W for the butanol 6% aqueous solution and 250 W for water. The 2-butanol 20% aqueous solution improves the performance of LHP by about three times compared with water, and the lowest total thermal resistance is only 1/4 of that of water as the working fluid, which is significantly reduced, so the 2-butanol 20% aqueous solution is the ideal formula to improve the performance of LHP. Therefore, the 2-butanol 20% aqueous solution is the ideal formula to improve the performance of LHP.