Temperature distribution and energy consumption in impinging jet and mixing ventilation heating rooms with intermittent cold outside air invasion

Abstract

For spaces with occupants coming in and out frequently, e.g., airport terminals and commercial buildings, the intermittent opening of the entrance door causes masses of cold outside air to invade the heating space in winter, and this leads to an increase in the heating energy demands. As impinging jet ventilation (IJV) has a potential for reducing high energy consumption compared to the use of mixing ventilation (MV), a series of experiments were conducted to investigate the temperature distribution and energy consumption of IJV used in a space with cold air invading intermittently and compared with those in a MV system. The results indicate that the door opening frequency only affects the amplitude of temperature fluctuation with time for a fixed door opening duration. The floor-to-ceiling temperature difference in the IJV is always less than 60% of that in the MV for different durations of door opening, proving that the former consumes less heating energy. Moreover, the increase of the inertia to buoyancy ratio on the supply air can improve the thermal environment and reduce energy consumption for both IJV and MV, with this improvement better in IJV than in MV, meaning that IJV is more energy efficient than MV when used for heating space with cold air invasion.