Our mission: find all the ways to improve air cooled heat exchanger efficiency. Following this vision, we developed a fogging solution.
The performance of many industrial processes is affected by the surrounding air temperature. Cooling in air coolers is less effective during periods of intense heat, affecting the functioning of the whole system.
The dimensioning of the unit exchange surfaces is a technical and economic compromise based on the average climate conditions. In the event of severe heat, the processes are less well controlled, which impacts the efficiency of entire plants.
High-pressure misting is the solution to stabilise the performance of air condensers and air coolers as well as gas turbines.
AX System offer misting solutions for adiabatic cooling on the basis of its knowledge of air coolers and high pressure.
Optimising adiabatic cooling
The idea is to project water, in the form of millions of little drops, into the air which is about to pass through the heat exchanger. Once the water has mixed with the air with an extremely large contact surface, it vaporises (passes from drop state to gaseous state). The water vaporisation absorbs energy, which has the effect of cooling by a few degrees the hot and dry air that was available. It is the same physical phenomenon which explains why you feel cold when getting out of the shower.
It’s essential that the quantity of water injected and the size of the drops be well controlled so as to avoid liquid water landing on the radiators, which are often metallic and sensitive to corrosion.
Misting is very suitable in terms of improving heat exchange by artificially lowering the air temperature, as an additional measure in areas where the air temperature range is high. This therefore prevents exchange surfaces being too big.
Adiabatic cooling by water misting is to a certain extent a booster which is relatively intermittent and optimises cooling in industrial environments.
Fogging modular solution
Our fogging solution is based on stackable modules, comprising up to 36 nozzles. The 0.4 mm diameter nozzles are spraying 10 microns water droplets, which evaporate when in contact with the air. During this state transition from liquid to vapor, an adiabatic reaction is absorbing calories and decreasing the air temperature.
Each module can inject up to 5.4 LPM at 70 bar. The quantity of modules per heat exchanger depends on total flow rate necessary to attain the performances required.
For example, for an ACC, 100 modules can be installed, spraying, 540 LPM and decreasing the airflow temperature up to 6°C, depending on weather conditions (temperature and relative humidity).
- To be effective, the exchange area between the water and air must be as large as possible. The idea is to produce the smallest drops possible.
- This great skill is the key to the proper functioning of the cooling device.
- By controlling water under high pressure, we can obtain – through mineral nozzles measuring a few micrometres under 100 bars of pressure – a homogeneous and particularly fine drop population.
- Temperature and air humidity conditions may require a change in the flow of the water controlled by an automaton.