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Title: Cooling efficiency of a spot-type personalized air-conditioner

Here, this study defined Cooling Efficiency ( CE) of a Spot-type Personalized Air-Conditioning (SPAC) device as the ratio of the additional sensible heat removal from human body induced by SPAC and the device's cooling capacity. CE enabled the investigation of SPAC performance on the occupant's sensible heat loss (Q s) and thermal sensation by its quantitative relation with the change of PMV level ( ΔPMV). Three round nozzles with the diameter of 0.08 m, 0.105 m, and 0.128 m, respectively, discharged air jets at airflow rates from 11.8 L s –1 to 59.0 L s –1, toward the chest of a seated or standing human body with a clothing of 0.48 clo. This study developed a validated CFD model coupled with the Fanger's thermoregulation model, to calculate Q s in a room of 26 °C ventilated at a rate of 3 ACH. According to the results, Q s, CE and draft risk ( DR) at face had significant positive linear correlation with the SPAC device's supply airflow rates (R2 >0.96), and a negative linear correlation for ΔPMV. With DR = 20% at face, CE was always under 0.3, and ΔPMV was around -1.0–1.1. Interestingly, both CE and ΔPMV had themore » least favorable values for the air jet produced by the nozzle with the diameter of 0.105 m independent of body posture. In conclusion, although SPAC could lead to additional Q s by sending air at a higher airflow rate from a smaller nozzle, the improvement in cooling efficiency and thermal sensation had a limit due to draft risk.« less
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Publication Date:
Grant/Contract Number:
Publisher's Accepted Manuscript
Journal Name:
Building and Environment
Additional Journal Information:
Journal Volume: 121; Journal Issue: C; Journal ID: ISSN 0360-1323
Research Org:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; spot-type personalized ventilation; computational fluid dynamics; cooling efficiency; draft risk; sensible hear loss; predict mean vote
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1356328