Blower :

F1 cars don’t have fans built-in, as such, they rely on forward movement for airflow and cooling of the motor and brakes

So when the cars are stationary the teams create airflow with battery blowers that are custom-built to sit over the respective ducts and push air through. On hot tracks, dry ice is added to increase the cooling capability. 

Andrew Burden

The author Kiwi F1 Fan