4550 -- Experimental Study of Indoor Thermal Environment for Cold Air Distribution Systems Using Various Air Outlets

Cold air distribution systems have been attracting attention in recent years because of needs for saving energy. These systems have the advantage of reducing HVAC construction costs because ducts, fans, and all components can be downsized, but they have been slow in finding wide acceptance. There are various reasons for this, and one in particular is the fear that room conditions will deteriorate. Concerning systems that supply low-temperature air directly into the room, lowtemperature supply air may cause surface vapor condensation on outlets and cold drafts, which make room conditions uncomfortable. Otherwise, for systems using fan-powered units that mix indoor air and low-temperature supply air, the merit of saving energy is decreased because of the fan demand and increased initial costs. Against this background, we set up a cold air distribution system and experimented with direct supply systems under various conditions. In this paper, we describe the solution of surface vapor condensation and cold drafts and the development of an outlet designed to prevent such occurrences. We also report on a comprehensive evaluation of comfort performed through experiments with human subjects.

Units: SI