**3. Conventionally manufactured minichannel heat exchanger**

**Figure 7** illustrates the minichannel heat exchanger of 12 circular channels designed and fabricated conventionally to conduct the experimental tests. The material and geometry of the minichannel test section was shown earlier in **Table 5**, coupled with the operating conditions engaged to run the experiments.

Using the PAO base fluid, the flow and heat transfer characteristics of the minichannel test section were carefully evaluated to verify the integrity of the experimental facility and test procedures. The experiments on the PAO base fluid were first performed, and the test results were used as baseline data to compare with those of Ethanol/PAO nanoemulsion fluids of 4% and 8% wt% ethanol. A range of heat fluxes addressed earlier in **Table 3** was selected as heat inputs to simulate single-phase and two-phase flow heat transfer conditions. All the experiments performed in the present study were repeated five times, and the relative errors of test data were found to be less than 5%. The SANS measurements were performed on the samples only prior to initiating the experiments. However, previous studies on a similar water/PAO system have demonstrated that there are no remarkable structure changes of the nanodroplets before and after pool boiling tests inside an enclosed system [63].
