This study makes clear that mean skin temperature and skin wettedness do not remain constant but may vary under constant thermal sensations of "slightly warm", "warm" and "hot". The relationship between mean skin temperature and skin wettedness under the constant thermal sensation of "warm" is adequaltely expressed through a convex curve with a negative slope.
The study was carried out on 6 subjects. Each one is seated at a desk with a mounted PVS. During the experiment the room air temperature was controlled at 28C and the personalized air temperature was 25C. Several fluctuations were tested, air movement with a frequency of 0.2 Hz was preferred to 0.1 Hz and 0.3 HZThe subjects had a preference for a lower mean air velocity but were more distracted when air movement fluctuated (0,2 Hz) than when it was constant.
The authors introduce a new airflow characteristic, the equivalent frequency, as an integral measure for the frequency of the random velocity fluctuations in rooms. The aim of that study was to test the impact of the equivalent frequency on draught sensation for human subjects. Further investigation at different air temperatures along with different turbulence intensities of air velocity is recommended.
CFD is used to simulate the effects of respiration in displacement ventilated rooms. It was done in a satisfactory manner.An extra simulation was carried out with "density-corrected" exhalation temperature, to see if the results are sensitive to variations of this parameter. This proved not to be the case. The choice of the flow rate is more important for the flow pattern.
16 segmental and all body heat transfer convective coefficients were determined in tests performed with a thermal mannequin placed in the test chamber of a large wind-tunnel.This paper presents a general table with the numerical coefficients of the equations representing the evolution of the convective coefficient with the flow velocity for all the studied cases (front, back and side flow - at seated and standing postures) . The effect of natural convection is more obvious on the central part of the body. Peripheric parts have stronger losses.
In order to identify the complex flow located at the breathing zone of a seated person exposed to the airflow coming form a PVS (personalized ventilation system) two techniques are used and compared : the PIV ( a two-dimensional particle image velocimeter) and the LDA (laser doppler anemometer) technique with a single point measurement, given by a cross section of laser beams.
The PIV technique appears a very interesting tool in studies aiming at identifying airflow in rooms or around objects.
A new type of thermal manikin DRESSMANN (Dummy Representing Suit for Simulation of huMAN heatloss). is presented : it consists of an overall, that can be worn by a person or a manikin, on which up to 32 heated sensors (artificial skins) can be fixed everywhere by velcrose fastening.
DRESSMANN presents the advantages of heated dummies and of small sensors . It can be used in buildings, vehicles, planes or trains.
For that study , an heated manikin, in a seated position, is exposed to a local thermo ventilator that promotes a non-uniform horizontal flow ( front , behind and right side) ; an interior climate analyser measures the environmental variables around the manikin. Those data are used as inputs of the numerical program.
A numerical model simulates the human and clothing thermal systems and evaluates the thermal comfort level. Verification was made that when the ventilator is places in front of the manikin, acceptable thermal comfort conditions are fullfilled.
This paper reports a large-scale investigation result on seat occupancy rate in a typical Japan office with 240 workers. The experiment lasted 3 months. The sensing device continuously recorded the seating status for about one week for each working person. From these results , a practical use situation of the personal air-conditioning system in the office could be predicted.
The aim of that study is to make a database of the local convective heat transfer coefficients for each part of a human body in sedentary and standing environments through the use of an experimental thermal manikin and an analysis of the radiative heat transfer rate. The results are applicable to both indoor and outdoor environments.
The paper also discusses the influences of wind velocity, sensible heat loss, posture and furniture arrangements on local convective heat transfer coefficients values.