# Evaporative Mist Cooling as Heat Dissipation Technique: Experimental Assessment and Modelling
## 4 Results and Discussion
### Experiment 3  
An analysis was run on the validated and calibrated simplified characterization model developed on the grounds of empirical findings to determine model sensitivity to the input variables. Experiment 3 was consequently designed to analyze the effect of the model variables with an impact on system  
Figure 11: Validation and calibration of the model for HARDI ISO F-110-04 nozzles.  
Figure 12: Validation and calibration of the model for HARDI ISO F-110-06 nozzles.  
performance. More specifically, nozzle height and pressure were the two parameters analysed based on the findings for weeks 4 and 5. The figures below give the daily mean values.  
Figure 13 graphs the variation in mean cooling efficiency with nozzle height. Changes in height entailed differences in droplet travel distance and with it residence time or the time the droplet was suspended in air. Consequently, the higher the nozzle, the longer the travel distance and residence time, which raised efficiency. The maximum height was set at 0.6 m to reduce the number of droplets travelling horizontally due to wind action.  
The variation in mean cooling efficiency with working pressure is shown in Figure 14, using manufacturer-specified values [39]. Pressure had a direct effect on nozzle flow and droplet scatter, as Figure 14 shows, with efficiency rising with pressure. More specifically, pressure affected the rate at which the water cooled.  
Figure 14: Variation in mean cooling efficiency vs. working pressure.  
Figure 13: Variation in mean cooling efficiency vs. nozzle height.  
Table 2 summarizes mean overnight cooling efficiency as calculated from Equation (9) for each day of the experiment, excluding week 1, based on the variables affecting the proposed model and the simplified, experimentally validated model for the two nozzles.  
The data show that efficiency was greatest where sprayer height and working pressure were highest.  
The percentage of water evaporating overnight graphed in Figure 15 for all seven days in weeks 2 through 5 shows that water loss from the ponds was no greater than 6% on any of the days tested. That value is equivalent to a mean loss of 2 L/h during the month, less than reported in other studies on evaporative cooling, according to [PERSON] et al. (2016). The findings not only validated the efficiency of this passive natural cooling technique but also ruled out the hypothesis that such systems entail high water consumption.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & Day 1 & Day 2 & Day 3 & Day 4 & Day 5 & Day 6 & Day 7 \\ \cline{2-7}
**Week 1** & & & & & & \\ \cline{2-7}  & & & & & & \\ \cline{2-7}  & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 \\ \hline  & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 \\ \cline{2-7}
**Week 2** & 0.51 & 0.57 & 0.59 & 0.53 & 0.54 & 0.52 & 0.56 \\ \hline  & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 & Experiment 2 \\ \cline{2-7}
**Week 3** & 0.52 & 0.50 & 0.51 & 0.58 & 0.47 & 0.49 & 0.50 \\ \cline{2-7}  & Experiment 3 & Experiment 3 & Experiment 3 & Experiment 3 & Experiment 3 & Experiment 3 \\ \cline{2-7}
**Week 4** & 0.43 & 0.53 & 0.65 & 0.64 & 0.65 & 0.70 & 0.37 \\ \hline  & Experiment 3 & Experiment 3 & Experiment 3 & Experiment 3 & Experiment 3 & \\ \cline{2-7}
**Week 5** & 0.47 & 0.58 & 0.61 & 0.66 & 0.68 & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mean daily efficiency.  
Figure 15: Daily evaporation (%).  
Water consumption is a prominent variable in evaporative cooling technique analysis, as discussed by other authors seeking to lower that parameter [57; 58]. The specific consumption (consumption/energy dissipated) found here lay within the range reported in the aforementioned papers.