The Study On The Performance And Supply Air Porperty Of Desktop-Based Task-Ambient Air Conditioning

Task-ambient air conditioning (TAC) system can produce a better thermal environment and breathing air quality than the traditional air conditioning. But in TAC systems, the supply nozzles are close to the people so there need more discussion about the comfort of the TAC system. The supply nozzle and the property of supply air including temperature and volume will effect its thermal environment and energy consuming.This research bases on lab test and aims to research the performance of TAC system and the environment in task area. A workstation simulating a typical office desk with desktop-based TAC system was established in a Controlled Environment Chamber to research the performance of TAC system. The user's votes were also used to study the property of supply air and comfort of TAC system in order to give suggestion to the design of supply air.To increase the turbulence intensity and decrease the potential draught, impact jet supply air was used in TAC air supply and the result showed this method could increase the turbulence intensity by 20% and reached above 0.6, a number which is very close to 0.6-0.8, the turbulence intensity of natural air movement.The test result shows that the adjust range of TAC system is very wide. By different supply air, the velocity from 0m/s to 0.6m/s and the temperature from 23℃ to 30℃ can be gained in task area. The comfort test showed that when using PMV as the index to predict the thermal sense in task area there would be difference, and the user adjusted the TAC system mostly depended on the velocity they felt, but their thermal sense would also changed after their adjust. It is suggest that the ambient temperature could be set at 30℃, and the ambient temperature and supply air volume shouldn't be set at a high degree; supply air temperature shouldn't lower than 21℃ if the ambient temperature is more than 28 ℃. If ambient temperature is lower than 28 ℃, supply air temperature should no lower than 23℃. The upper limits of the volume should be 190m3/h and the lower limits should no less than 60m3/h to satisfy the basic demands for fresh air.