# Influence of Burner Nozzle Parameters Analysis on the Aluminium Melting Process
## 3 Results and Discussion
### Results of Experimental Measurements  
The correctness of the chosen methodology (measurements using the experimental device) can be confirmed by comparing the achieved results with those obtained by a group of American scientists. [PERSON] and [PERSON] (2010) studied the influence of oxygen concentrations in the oxidizer on the furnace productivity and operating costs for 10 ton rotary melting furnaces. Power consumption for heating, melting, and overheating 1 kg of the charge was used as a main criterion for the evaluation of the benefits of the optimisation of burning natural gas in the process of oxygen enrichment from the oxidizer. Figure 6 shows the results of the experimental measurements. The blue line illustrates the results obtained by [PERSON] and [PERSON]. The red line illustrates the results obtained by experimental measurements using the ordinary air nozzle. The green line illustrates the results obtained by experimental measurements using the optimized air nozzle. The impact of the enriched oxidizer on the process of aluminium melting in the experimental device is comparable with the experimental results obtained by [PERSON] and [PERSON] (2010). At oxygen concentrations above 30%, no significant reduction occurs in the specific fuel consumption required for heating and melting the charge. The difference in the specific heat energy consumption needed for melting the charge results from higher heat losses of the experimental device, the differences in the amount of charge, and the output and size of thermal aggregates. Complete verification requires the inclusion of these factors into calculations of the results obtained from the experimental device. Based on the experimental measurement results, it is obvious that the use of optimized air nozzles can result in the reduction of the fuel consumption for charge heating and melting by 21%, while the oxidizer oxygen concentration remains at the same level, approximately 30%. As already noted, the efficiency of this device depends on the amount of available heat released in the thermal aggregate. The amount of available heat is influenced by the heat loss from exhaust flue gases, which is calculated on the basis of the measured temperature of the exhaust flue gases. The temperature of the exhaust flue gases in the experimental device chamber was about 700 \({}^{\circ}\)C. Based  
Figure 6: Comparison of energy consumption per 1 kg of charge depending on the oxidizer oxygen concentration (Adapted from (2010), calculated from the experimental measurement). on the calculations, the amount of available heat in the experimental device reached as much as 82% of the supplied heat at 45% enrichment of the oxidizer. Figure 7 illustrates the influence of the oxygen concentration on the energy efficiency of the experimental device. The value of the energy efficiency of the experimental device rises with the increased oxygen concentrations in the oxidizer. As a result of the optimisation of the air nozzle, the heat transfer from the flame is directed to the charge, thus increasing the efficiency of the experimental device. At 30% oxygen concentration in the oxidizer, the energy efficiency increased by 4% due to the air nozzle diameter optimisation. As illustrated in Figure 7, the amount of available heat is not influenced by the air nozzle diameter changes. Based on the dependencies shown in Figure 7, the course of heating the charge in the experimental device due to the increased oxygen concentration cannot be determined. Figure 8 graphically illustrates the changes of the mean temperature of the charge during the experimental measurement using the ordinary (not optimized) air nozzle. Aluminium melting is defined as a phase transformation from the solid state to the liquid one. Crystalline substances, including aluminium, are melted at a constant temperature; however, at the same time, a slight overheating of the melt being formed occurs, which also suggests a slight increase in the temperature within the melting interval in the graph (Figures 8 and 9).