Investigating the Effects of Air Bubbles Injection Technique on the Cooling Time of Warm Drinking Water

Abstract

This paper deliberates experimentally the inspiration of capacity flow rate of air bubbles inserted on the time period of a water cooler container with 30 liters of regular water initially at 37 °C. Four various volume flow rates of the injected air were used in the experiments (Qa=0.5; 1.0; 1.5 and 2.0 LPM). The air was injected into the water basin from the bottom as small air bubbles with an average diameter of (0.1 mm) via a spiral sparger made of silicon tube with (1400) holes and 0.1 mm hole diameter. In addition, four air pressures (P=2, 3, 4, and 5 bar) were used in the experiments. Consequences exhibited that the time required to cool down the water temperature (about 5 °C) was much smaller with injecting air bubbles than that of without injecting air bubbles (using the traditional cooling method). This consequence was more pronounced with amassed the volume airstream of the inserted air bubbles. The escalation the air volume flow rate, the quicker reduction the water cooling. Also, it was found that the pressure of the injected air bubbles had only a minor impact on the cooling process. Furthermore, the heat transfer and the cost of the cooling process with and without injecting air bubbles were studied. The heat transfer convection coefficient correlated of Nu was investigated to be increased with rising the volume flow rate of the injected air bubbles. Similarly, the cost of cooling down a specific amount of water was noticed to be decreased with increasing the injected air bubbles., The calculations illustrated that small air bubbles motility amount have a very significant guidance on time. The possibility of reaching the end of the cooling process can be achieved quicker as air flow rate amount is increased. It was clear how much electricity is saved using air bubble inoculation technique.