Impact of Focus- and Diffuse-Type Air Vents on Cabin Thermal Comfort
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ght © 2020 KSAE/ 11724 pISSN 12299138/ eISSN 19763832
IMPACT OF FOCUS- AND DIFFUSE-TYPE AIR VENTS ON CABIN THERMAL COMFORT Daewoong Lee1)* and Hoseong Lee2) APIC, R&D Division, Hanon Systems, 95, Sinilseo-ro, Daedok-gu, Daejeon 34235, Korea Thermal Management R&D Center, Korea Automotive Technology Institute, 303, Pungse-ro, Pungse-myeon, Dongnam-gu, Cheonan-si, Chungnam 31214, Korea 1)
2)
(Received 8 April 2019; Revised 9 July2019; Accepted 26 August 2019) ABSTRACTAs the automotive industry has grown and lifestyle has changed, the time spent in an automobile has been gradually increasing. Accordingly, thermal comfort for passengers inside the cabin of an automobile is more important than before. Thermal comfort can be affected by several factors, such as temperature, humidity, and air distribution inside the cabin, as well as airflow rate and air velocity from the air vents and air-handling unit (AHU). The aim of this paper is to investigate the impact of changes in the pattern of discharge air from air vents connected with the vent duct and AHU on the thermal comfort in an automobile. The changed patterns of discharge air were of three types: diffuse-mode, focus-mode, and mixmode. Cool-down performance and auto temperature-control performance experiments were performed to evaluate the thermal comfort of the front and rear passenger seats in the climate control wind tunnel. In addition, a road driving evaluation of the temperature difference between front and rear seats with two passengers was performed. As a result, focus- and diffusetype air vents can be helpful for improving thermal comfort of passengers and the air stream of the cabin. KEY WORDS : air-handling unit, airflow rate, air direction, auto-temperature control performance, cool-down performance, HVAC, thermal comfort
NOMENCLATURE
passing through the duct in the air-handling unit (AHU), is directed up/down or left/right depending on the preference of the passenger, or the air vents can be closed when blowing air is not wanted. From the perspective of airflow, it is better to distribute the airflow evenly inside the whole vehicle, but because the air blows from the front, a difference occurs between the front seats and rear seats and between the upper and lower level of a passenger. Therefore, thermal comfort is different between the seats depending on the direction of the airflow. Currle and Maue (2000) conducted a study on the air discharged and its thermal comfort to the face from the AHU. By changing the size of the driver side vent, driver center vent, passenger center vent, and passenger side vent, the airflow volume and velocity was examined through computer analysis. Furthermore, the effects made on the thermal comfort at the front and rear seats were compared. Ozeki et al. (2008) fabricated a cabin reduced to onehalf scale by using acrylic resin, and tested the performance of ventilation by measuring the airflow with particle image velocimetry (PIV) and measuring the age of the air with the trace gas method. Furthermore, by using computa
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