CFD Study on the Ventilation Effectiveness in a Public Toilet under Three Ventilation Methods

The indoor air quality (IAQ) of severely polluted toilets is associated with the transmission of diseases. Computational fluid dynamics (CFD) methods and experimental measurements were used to analyze the diffusion characteristics of pollutants. This study investigated the diffusion characteristics and normalized concentration of ammonia and hydrogen sulfide pollutants under three ventilation systems—mixing ventilation (MV), personalized ventilation (PV), and impinging jet ventilation (IJV)—in a public toilet. The mean age of air (MAA) and air exchange efficiency (AEE) were also analyzed in our study. The results show that the MV scheme has a poor removal effect on pollutants compared with PV and IJV. IJV has advantages in reducing the normalized concentration of pollutants and improving the IAQ. Increasing the number of air changes per hour (ACH) may lead to a longer MAA and reduced air exchange efficiency. Choosing an appropriate number of air changes is very important to improve the IAQ in the toilet.

Experimental investigation of occupants’ thermal sensation under a personalized ventilation system

By considering the importance of providing proper indoor environment conditions for occupants and also due to energy costs, one of the solutions for indoor local air-conditioning is Personalized Ventilation System (PVS). In this paper, the occupants’ thermal sensation was experimentally studied for body segments that are mostly affected by the PVS. The local sensation of head, chest, arm, and hand at two supply air temperatures of 16 and 32°C were investigated. Eight volunteer subjects participated in this survey. The subjects reported the most thermal satisfaction on their hands. Also, the arms were the segments with the coolest thermal sensation (-1.28, between slightly cool and cold). Results indicate that the head’s thermal sensation at both supply air temperatures was neutral and the hand was the only body part that experienced warm thermal sensation during the test. Also, by increasing the supply air temperature to 32°C whole body thermal sensation changed from -0.46 to -0.09 on the seven-point scale, which means that the cooling system worked properly for occupants’ cooling. In this system, cooling occurred at 32°C instead of the common 16°C supply air temperature, which results in energy-saving and decreases annual running costs.

Development and application of an integrated virtual thermal-acoustic manikin design used inside an office space

In this study an integrated virtual thermal-acoustic manikin design used inside ventilated and occupied office spaces is developed and applicated. The component of the virtual thermal manikin evaluates the internal airflow and occupants' thermal, thermo-physiology and clothing systems and calculates the thermal comfort and the indoor air quality levels. The component of the virtual binaural manikin evaluates the direct and indirect sound and calculates the reverberation time. The space geometry with complex topology is developed using a Computer Aid Design (CAD), while the occupants' geometry is made using geometric equations. The grid generation, in the surrounding space surfaces and around the external occupants' surfaces geometry, is used to calculate the radiative heat exchanges and the sound propagation. In this study, performed in an office room occupied by eight persons and equipped with personalized ventilation system, the thermal comfort level, the air quality level and the space reverberation time is evaluated and discussed. In accordance with the obtained results the values are, in general, in accordance the actual standards.