Special requirements apply to marine applications, e.g. on cruise ships, due to the salt levels. Functionality is important, as is corrosion resistance. This is why rotors have become established for heat recovery. Further advantages:

  • Compact design
  • High degree of efficiency
  • Humidification and dehumidification

A specific stainless storage mass with sorption coating is used as storage mass in the seawater-resistant design. Its usability for this application was tested in a salt spray test (duration: 1000 h) according to ISO 9227.

Double-rotor concept


In regions with high outdoor temperatures and humidity or buildings with dry cooling systems, the supply air needs to be cooled, dehumidified and heated. Hoval double-wheel concept works much more effectively than other systems.

Process principle

  • Sorption rotor: cools and dehumidifies warm outdoor air very effectively.
  • Cooler: lowers the temperature to the dew point of the required room temperature.
  • Condensation rotor: warms the outdoor air to the required supply air temperature. The condensation rotor cools the extract air at the same time so that the sorption rotor can work even more efficiently.

The double-rotor concept is very efficient and can result in savings of up to 60% in the overall cooling effort compared to conventional systems. This reduces the investment and running costs considerably.

Wood drying


The entire system is made up of two modules:

  • Recovery module (provided on-site)
  • Condensation module (Hoval
                plate heat exchanger with 4P gasket)

In the recovery module, the drying air is saturated through circulation and reheating until an ideal saturation point is reached. A partial flow of this high-energy air is supplied to the condensation module and the Hoval plate heat exchangers then come into play with this. This latent energy preheats the outdoor air in the condensation module. This guarantees extremely efficient drying. The Hoval plate heat exchanger recovers a large proportion of the energy used. It is possible to achieve annual savings of 35 to 55%.

Offshore wind turbines

Wind Energy Converter_en-2

High temperatures are produced by generators inside the nacelles of offshore wind turbines. Hoval plate heat exchangers provide reliable and energy-efficient cooling here. They transfer the heat energy contained in the nacelle extract air to the outdoor air or the wind with up to 87% efficiency. Well-cooled generators work more efficiently and give the operator a higher electricity yield. As the air flows in the plate heat exchanger are completely separate, the machinery in the nacelle cannot be impaired by the aggressive, salty sea air.

Process principle

The system uses a fan to extract the warm air from the nacelle and directs it across the plate heat exchanger. At the same time, cool outdoor air, driven by the wind, flows through the plate heat exchanger. The waste heat from the nacelle extract air is transferred to the cooler sea air by heat conduction as a result of the temperature difference. The cooled air is then routed back into the nacelle via ventilation shafts.