Submitted by Maria.Kapsalaki on Mon, 03/21/2016 - 11:08
Conventional Displacement Ventilation (DV) system has been installed in an office of a Zero Energy Building (ZEB). Enhanced DV (EDV) system, consisting of fans mounted to the chair, which has been demonstrated in laboratory and field environmental chamber studies earlier was implemented for the first time in a full-scale office environment to assess its effectiveness of improving the thermal sensation of the occupants. Objective measurements and subjective assessments were conducted in the office with 12 occupants over a period of 2 weeks.
Submitted by Maria.Kapsalaki on Wed, 07/02/2014 - 21:27
Providing cooling effect with low energy consumption makes the exploration of air flow utilization significative. In ASHRAE Standard 55-2010, the cooling effects of elevated air movement are evaluated using the SET index as computed by the Gagge 2-Node model of whole-body heat balance. Air movement in reality has many forms, which might create heat flows and thermal sensations that cannot be accurately predicted by a simple whole-body model, and the affected body surface might be variably nude (e.g. face) or clothed.
Submitted by Maria.Kapsalaki on Tue, 06/17/2014 - 14:53
It is well known that humidity influences cooling load, thermal comfort and durability of buildings and various items in them. Many works on prediction of humidity variation in a room have regarded the humidity as unique in a space. However, it does depend on air movement. This paper describes calculations of minute moisture distributions in a room affected by moisture buffering of porous walls. The air velocity distribution is calculated by CFD using two different turbulence models. Then the heat and vapor transient transport in walls and space is calculated.
A building contains a number of large openings, such as doors and staircases. When the temperature of the spaces connected by these openings differs, the difference in density will cause air movements through them.Horizontal air movements through vertical openings in buildings, such as doors and windows are wellinvestigated while studies of air movements through horizontal openings, such as stairwells are less frequent and therefore this work focuses on this case.
We already have had theoretical model to predict temperature and humidity variations in a room. Manyworks have estimated the accuracy of the numerical model, but they might be influenced by the airmovement. Thus, theoretically the temperature and humidity variations should be solved with airmovement in a room. In this paper, I calculated the minute temperature and moisture distributions in aroom which has the moisture buffering effects by the porous walls. The room space is regarded asrectangular box which has two hole, inlet and outlet for ventilation.
We consider the overnight evolution of an initial two-layer thermal stratification (a warmupper layer and a cooler lower layer) in an enclosure ventilated via openings at high and low levels.Results of our laboratory experiments show that an efficient displacement flow is not always established and four distinct ventilation flow regimes are observed depending on the ratio R (= at /ab ) of the upper opening area, at , and lower opening area, ab ( > 0). For a given initial stratification, displacement flow is established only if R is sufficiently small (i.e. at
Experiments were carried out to study transition phenomena in buoyancy-induced natural ventilation in a relatively large-scale enclosure equipped with a localized heat source and two openings (upper and lower) on one of the sidewalls. The process studied is transition from the mixing to the displacement ventilation mode realized by opening the lower vent to different heights while keeping the upper vent fully open. Measurements included inside vertical temperature profiles and air velocity through the upper vent.
The aiflows driven by a revolving door that links two rooms of initially uniform temperature are examined. Two situations are considered, the first in which the rooms are at equal temperature, and the second in which there is a temperature difference between the rooms.
The flows were examined using a small-scale model of a revolving door and with fresh- and
salt-water solutions to represent temperature differences. The results presented herein reveal
how the transfer of air across a revolving doorway depends on the rotation rate and temperature
Individual differences in preferred air temperature may be as great as 10°C, and preferences for air movement may differ more than four times for the occupants. Personalized ventilation can improve occupants' comfort in so far as thermal discomfort is oft