Frost issue in heat exchangers

The formation of frost in air-to-air heat exchangers is a persistent issue in locations with temperatures below -5°C. Condensation occurs when some of the transfer surfaces temperature drops below the dew point of the warm airstream, and this condensation turns to ice which causes the heat exchanger to consume energy. This happens as a result of the ice formation reducing the air section and increasing pressure loss, so there are more consumptions from fans.

Depending on the temperature of the air supply, humidity of exhaust air, and the efficiency of the heat exchanger the rate at which frost will accumulate will vary. In regions with persistent freezing temperatures or no fluctuation in temperature above freezing airflow can stop completely after frost or ice formation. Between countries, there are different ways of dealing with ice formation: shutting-off fresh air inlet or by-passing the heat exchanger. In one case the ventilation recycles stale air over and over (bad Indoor Air Quality) and in the other it stops recovering the heat from return air.

A classic issue in cold climate is to over-heat or shut down the ventilation function to prevent frosting, but this goes against performance and air quality requirements. However, F2A, a French leading company in ventilation and heat exchanging technology, is developing an innovation to solve this issue with their next generation of heat exchangers.

The patented solution will operate with integrated bypass, anti-frost functions, and alternate between different flow techniques to achieve unique performance.

To face the freezing issue while keeping the best efficiency, F2A’s next generation heat exchanger combines co-current and counter-flow principles in one single product. This innovative feature enables a high efficiency with counter-flow technology, and a proper functioning down to -20°C by switching to a co-current flow at low temperatures.

Co-Current functioning : Prevents freezing at low temperatures while recovering heat from return air.

This cold climate issue affects 2/3 of EU countries and all of the Northern and Eastern European countries along with North America and Russia. Existing heat recovery solutions are not able to deal with frost issue and negatively impact the efficiency of the overall building.

F2A’s breakthrough innovation will provide a real energy and cost saving solution.

For further information regarding F2A’s solutions : come see us at ISH Trade show in Hall 11.1 Booth 88.