Numerical Modelling of the Draught Rate in a Mechanically Ventilated Climate Chamber

Abstract

The thermal environment in an indoor space is determined by the thermal state of the human body, and the local thermal discomfort. The draught rate (DR) is one of the indices for thermal discomfort. The achievement of air distribution without draught is one of the goals of the ventilation methods. It is especially important in the design of climate chambers, where the volume is small, and the research studies may require prolonged occupants’ exposure. Our study shows results from the CFD simulations of a mechanically ventilated climate chamber, performed in the design stage of the chamber’s construction. Velocity profiles distribution, temperature distribution and DR are used to assess the thermal comfort of the person in the chamber. The results obtained allowed designing of the proper indoor environment with desired characteristics for air distribution and human exposure.

Prediction of exhaled carbon dioxide concentration using a computer‐simulated person that included alveolar gas exchange

“…On the contrary, the simulation by Wang et al 54 that focused on the CO 2 concentration in a personalized work environment (PWE) showed that the inhaled CO 2 concentration was higher than the volume‐averaged concentration over time, which could be caused by upward flow towards the ceiling. Angelova et al 38–40 also indicated that a region of high CO 2 concentration (1200 ppm and above) was formed in front of the occupant's head when there was downward flow from the ceiling, and they assumed that the inhaled CO 2 concentration differed from the CO 2 concentration measured at both the inlet and outlet of the chamber. Thus, the flow field in the breathing zone and the locations of the outdoor supply inlet and exhaust outlet strongly affect the inhaled CO 2 concentration.…”

“…showed that the inhaled CO 2 concentration was higher than the volume-averaged concentration over time, which could be caused by upward flow towards the ceiling. Angelova et al [38][39][40]…”

“…For this purpose, CSPs incorporating a computational fluid dynamics (CFD) approach were developed because they make it possible to simulate the non-uniform airflow pattern and temperature distribution surrounding the human body indoors, together with CO 2 emissions from breathing. [32][33][34][35][36][37][38][39][40] Bulińska and Buliński 35 analyzed three different breathing models that simulate a micro-environment around the human body, particularly the CO 2 concentration distribution emitted by a sleeping person. They confirmed that complete breathing with inhalation and exhalation should be included in an accurate prediction of contaminant transport from humans.…”

“…Prediction of human CO 2 emissions during continuous breathing with inhalation and exhalation modes requires reliable modeling of human interaction with the ambient indoor environment. For this purpose, CSPs incorporating a computational fluid dynamics (CFD) approach were developed because they make it possible to simulate the non‐uniform airflow pattern and temperature distribution surrounding the human body indoors, together with CO 2 emissions from breathing 32–40 . Bulińska and Buliński 35 analyzed three different breathing models that simulate a micro‐environment around the human body, particularly the CO 2 concentration distribution emitted by a sleeping person.…”