An ‘intelligent’ flow sensor said to enable ventilation to adapt to actual demand, thereby improving indoor air quality and energy efficiency, has been jointly developed by Finland’s VTT Technical Research Centre and Fläkt Woods Oy, part of global air technology specialist, FläktGroup
The flow control utilises a flow sensor based on ultrasound, which is said to be ‘ideal for use in challenging hospital conditions’. VTT and Fläkt Woods Oy said: “Existing ventilation systems are based on estimated average occupancy rates, and cannot adapt to unexpected changes in them. For example, the air can be poor in a meeting room due to inadequate ventilation if more than the expected number of occupants arrive, or the ventilation can be humming away in an empty room, wasting energy.”
Under a joint project funded by Tekes, VTT and Fläkt Woods have developed a new flow sensor, ‘which enables reliable measurement across the entire speed range, even at low flow rates’. No ‘dirt-gathering’ or bulky measuring devices are needed for the ventilation system, and the ‘maintenance-free, quiet, precise, and intelligent sensor solution’ does not cause pressure drops.
“An ultrasound pulse is transmitted in the radial direction of the air channel, and is measured differentially, says Anu Kärkkäinen of VTT, who is leading the research team. “This measurement system enables us to eliminate several sources of error, and obtain highly accurate measurements.”
“The new flow controller allows just the right volume of air to be pumped into a room, based on the current load,” added product manager, Timo Kaasalainen, of Fläkt Woods. “We estimate that demand-controlled ventilation reduces energy costs by 45-50 per cent.”