The extent to which the room is cooled is limited to ensure the thermal comfort of people in the frequented area. High cooling capacity means high volume flows and low supplied air temperatures at the unit’s air outlet. However, in the frequented area, it is precisely this combination that leads to draughts – the most frequent cause of discomfort.
The task facing flow technology is to reduce both high air velocities and low temperatures by selectively mixing the air with the warm ambient air and increasing the turbulence over the short path from the unit outlet to the frequented area. Optimisation based on the use of suitable high-induction air diffusers and maximisation of the mixing ratio has been a consistently adopted solution for the last hundred years. Systems based on this approach have come up against their physical limits.
However, one of the premises behind this form of optimisation was the assumption of a stationary flow, i.e. a continuous supplied air volume. This makes sense in a context in which fans are considered as flow generators and in the light of the demand for unchanging acoustics. As long as 20 years ago, LTG started researching and using non-stationary transient systems for room air-conditioning applications.
It quickly became clear that a pulsed flow, achieved for example by means of eddies that transport cold air along the ceiling or by the cyclical introduction of supplied air, could greatly enhance thermal comfort. This results in stable flow effects that can be controlled using the new parameter “cycle duration” or “frequency”. It goes without saying that no compromises have been made in terms of acoustic performance and energy efficiency, and new benchmarks have been set here.