Every degree that ambient temperature rises, a gas turbine loses power output and efficiency, because hot air is less dense and the compressor moves a fixed volume rather than a fixed mass. On a hot summer afternoon, a turbine rated for peak output on a cool day can lose ten percent or more of its capacity right when grid demand, and electricity prices, are at their highest. Inlet air cooling with fogging nozzles is one of the most cost-effective ways to recover that lost output.
How Inlet Fogging Works
A fogging system injects a very fine water mist directly into the turbine inlet duct, upstream of the compressor. As the tiny droplets evaporate in the airstream, they absorb heat from the surrounding air, cooling it through the same evaporative process that cools skin when sweat evaporates. Cooler, denser air entering the compressor increases mass airflow, which directly increases turbine power output. Because evaporation happens in the duct rather than by refrigeration, the parasitic power draw is far lower than chiller-based inlet cooling.
Why Droplet Size Is the Critical Design Parameter
For fogging to work without damaging the compressor, droplets must evaporate completely before reaching the compressor blades. Oversized droplets that fail to evaporate can cause water erosion on compressor blades over time. This is why inlet fogging nozzles are specifically engineered to produce a very fine, tightly controlled droplet spectrum, typically in the 5 to 20 micron range, at the pressures and flow rates used in these systems. Nozzle count, spacing, and orientation in the duct are all calculated to achieve full evaporation within the available duct length and residence time.
Key Design and Selection Factors
- Droplet size distribution – The finer and more uniform the spray, the faster and more complete the evaporation before the compressor face.
- Water quality – Demineralized or high-purity water is normally required to avoid mineral deposits on compressor blades as droplets evaporate.
- Nozzle material – 316 stainless steel is standard for corrosion resistance and to avoid introducing metal particulate into the airstream.
- Duct layout and residence time – Nozzle placement must account for the available duct length and airflow velocity to ensure droplets fully evaporate before reaching the compressor.
- System pressure – High-pressure fogging systems (typically above 1,000 psi) atomize water into smaller droplets than low-pressure systems, improving evaporation efficiency.
Typical Benefits and Applications
Inlet fogging is used across simple-cycle and combined-cycle power plants, industrial cogeneration facilities, and standby generation sites wherever ambient temperature swings affect turbine output. Beyond peak-shaving power recovery, some facilities also use overspray fogging (intentionally injecting slightly more water than needed for full evaporation) for additional interstage cooling, though this requires careful engineering to avoid compressor blade erosion.
Maintenance Considerations
Fogging nozzles operate at high pressure with very small orifices, which makes water quality and filtration critical to long-term reliability. Scheduled filter changes, periodic nozzle inspection, and monitoring for any drift in droplet size or spray pattern all help avoid unplanned outages and protect compressor blades from erosion or deposit buildup.
Why Choose Jeltecn Inlet Fogging Nozzles
Jeltecn supplies fine-mist atomizing nozzles engineered for gas turbine inlet air cooling, with the droplet size control and stainless steel construction required for reliable, erosion-free operation. Our engineering team reviews your turbine model, ambient conditions, and target power recovery before recommending nozzle count, spacing, and system pressure.
Share your turbine model, inlet duct dimensions, and target cooling performance with our team to receive a nozzle layout recommendation and fast quotation.