Improvement Of Air Short Circuit For Ceiling-mounted Cassette Type Indoor Unit

Ceiling-mounted cassette type indoor unit is wisely used in such places as hotel and restaurant due to its outlook and more even temperature and velocity field. But with this unit, the treated air can't be sent to the working zone effectively and often result in air short-cut, which is more severe for heating.In this research the effects of sending air parameters including velocity, temperature and angle between the sending air and the ceiling on the distribution of air flow was investigated with some indexes, like temperature asymmetry coefficient, velocity asymmetry coefficient and energy utilization coefficient. The results of velocity asymmetry coefficient show that velocity has greatest influence on the air velocity distribution, the results of temperature asymmetry coefficient show that the interaction of velocity and temperature has greatest influence on the temperature field, while angle affects energy efficiency most as indicated by energy utilization coefficient.The reasons for air short circuit are also studied in this research. It's found that the sending air does not come to outlet directive like imagine. Because of the outflow, the sending air which curves to outlet can't be sent to working zone effectively, and leads to bad energy utilization. It's tried to optimize the air distribution by using baffles and broadening the distance between inlets and outlet. The results show that baffles can not but broadening the distance can improve the air distribution significantly.