Ceiling-based cabin displacement ventilation in an aircraft passenger cabin: Analysis of thermal comfort

Abstract

Applying energy efficiency enhancing technologies to the aircraft cabin ideally incorporates the passengers' comfort. Of current interest is the question of whether ordinary mixing ventilation (MV) systems in an aircraft cabin can be replaced by or combined with ceiling-based cabin displacement ventilation (CCDV) systems. A reduction of energy consumption by implementing CCDV without risking a decrease in thermal comfort would be a valuable gain. Different climatic scenarios were established by matching cabin displacement ventilation (CDV) from beneath the passenger seats with CCDV. Three ratios of supply air were arranged as treatments within a cross-over repeated measurement design (50%/50%, 70%/30%, and 100%/0% [CCDV/CDV]). As a baseline, a conventional MV scenario was assessed. In each CCDV/CDV scenario, 90 subjects were tested, in the MV-trial 45. The average cabin temperature throughout all tests was 23.5 °C with 610 l/s of supply air and approximately 25% relative humidity. Subjects rated the intensity of four climate parameters (air temperature, air velocity, humidity, and air quality) and corresponding comfort level. Significant differences in the perceived intensity of climate parameters between the four ventilation scenarios became obvious. Temperature was perceived to be highest in the 50/50 scenario and air draught was perceived as being strongest with MV. Comfort evaluations did not differ significantly between the four ventilation scenarios, but differential analyses showed that in the 50/50 CCDV/CDV scenario, a more homogeneous cabin air flow was found that led to improved thermal comfort for aisle seats.