HVAC automotive vents evaluation and their performance

Car passengers' comfort is increasingly important, not only from good feelings or travel comfort point of view, but also from the transportation safety perspective, where the driver's thermal comfort is of crucial importance. The main components affecting optimal comfort are HVAC vents. This article focuses on the performance assessment of a side dashboard car vent with adjustable horizontal vanes that allow changing the air jet direction vertically along with a complete shut-off. A new measuring methodology is presented here; it simulates real and complete ventilation system conditions using a simple laboratory piece of equipment with a single vent mounted. The flow pattern as generated by the vent jet was first studied with smoke visualization, then using a two-wire constant-temperature anemometer probe. Jet orientations and boundaries were identified for particular vent settings, which are fundamental in the assessment of vent performance. The average air speed and turbulence intensity were determined. Results show that the actual jet direction differs substantially from the direction that was set by the vanes and that further research may lead to a new and improved design of automatic control of a zonal ventilation system and contribute to more accurate control of passengers' comfort.