Spray nozzles for cooling systems

Engineering consideration 4 - Droplet size

As a general rule of thumb a cooling spray will remove more heat if the average droplet size is smaller.  This is because as the average drop size reduces the overall surface area of the spray increases (for more details see our Engineering Resource section on droplet size).  But in some cooling applications, particularly when cooling a fast moving gas or production line, care needs to be taken to ensure that the coolant spray reaches the whole target.  It is a simple fact of physics that larger droplets have greater momentum than smaller ones so these will naturally be able to reach areas that would not be visited by smaller drops.  As such, the simple rule of thumb that smaller droplets = more cooling does not always ring true. 

In situations such as this a balance and mix of droplet sizes is required for optimum cooling, with the large droplets reaching the furthest places and the smaller ones providing increased cooling power.  A range of nozzles giving different droplet sizes could be deployed or a nozzle such as the TF spiral nozzle which gives a broad spectrum of spray drops.

Successful v Unsuccessful Gas Cooling