**4. Conclusions**

The proposed heat transfer coefficient correlation archives the mean deviation of 20.66 and 21.06% for macro‐scale‐ and mini‐scale channel, respectively. The detail comparison of the proposed correlation and the experimental data is shown in **Figure 12**. **Figure 13** summarises the overall comparison of existing heat transfer coefficient correlation and the proposed one with the present data of R410A. Among the existing correlations, the one proposed by Gungor‐ Winterton [31] showed the best prediction for the macro‐channel with the mean deviation of 25% while this correlation failed to predict the heat transfer coefficient of mini‐channel. The heat transfer coefficient correlation proposed by Tran et al. [33] predicted the experimental

data with the mean deviation of around 30% for both macro‐ and mini‐channel.

24 Heat Exchangers– Advanced Features and Applications

**Figure 12.** Comparison between experimental and predicted heat transfer coefficient.

**Figure 13.** Summary of mean deviation.

The boiling heat transfer coefficient and pressure drop characteristics of R410A in horizontal tube with the inner diameter of 1.5, 3.0, 6.61 and 7.49 mm were demonstrated in this chapter. The data of heat fluxes ranging from 10 to 40 kW/m<sup>2</sup> , mass fluxes ranging from 100 to 600 kgm<sup>2</sup> /s, the vapour quality up to 1.0 and the saturation temperatures of 5–15°C. The results can be summarised as follows:

