Temperature of the film of soap bubbles turned out to be lower than the ambient air

(ORDO NEWS) — The film of air bubbles quickly evaporates and is thereby cooled. Experiments show that the difference in temperature can reach eight degrees.

Gas-filled bubbles are not just child’s play. They arise due to the action of surface-active substances (surfactants), are used in the mining and processing industry and generally play a big role in our lives.

There are even ideas to use them to pollinate plants. Therefore, scientists are putting a lot of effort in order to better understand the behavior of the bubbles and more precisely control them.

Emmanuelle Rio and colleagues studied the mechanisms that determine the stability of air bubbles obtained using ordinary water, soap and glycerin.

The scientists varied various parameters of the environment – temperature, humidity, concentration of surfactants and glycerol – tracking how they affect the behavior of the bubbles

In particular, they used a thermometer which made it possible to measure the temperature of the blistering film. A sensitive instrument has shown that it can drop well below ambient temperature.

The reasons for this are quite obvious. Moisture from the surface of the bubbles quickly evaporates, and evaporation is an endothermic process that goes with the absorption of heat.

It is this that allows our body to cool in the heat by evaporating sweat from the surface of the skin. However, until now this nuance has escaped the attention of researchers.

New experiments have shown that due to evaporation, the surface of the bubbles can be several degrees colder than the surrounding air.

The degree of film cooling depends on the intensity of evaporation, which, in turn, is determined by a number of medium parameters.

In particular, glycerin, which increases the stability of the bubbles, slowed down their evaporation and weakened cooling.

But under optimal conditions, the difference in temperature could reach quite impressive values, up to 8 ° C.

The discovery of French physicists will make it possible to more accurately predict the behavior of bubbles and better control it.

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