Numerical and Experimental Modeling of Indoor Air Quality Inside a Conditioned Space with Mechanical Ventilation and DX-Air Conditioner

2020 ◽  
Vol 38 (9A) ◽  
pp. 1257-1275
Author(s):  
Wisam M. Mareed ◽  
Hasanen M. Hussen
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Thermal Conditions ◽  
Airflow Rate ◽  
Air Conditioner ◽  
Breathing Zone ◽  
Lecture Room ◽  
Ventilation Performance

 Elevated CO2 rates in a building affect the health of the occupant. This paper deals with an experimental and numerical analysis conducted in a full-scale test room located in the Department of Mechanical Engineering at the University of Technology. The experiments and CFD were conducted for analyzing ventilation performance. It is a study on the effect of the discharge airflow rate of the ceiling type air-conditioner on ventilation performance in the lecture room with the mixing ventilation. Most obtained findings show that database and questionnaires analyzed prefer heights between 0.2 m to 1.2 m in the middle of an occupied zone and breathing zone height of between 0.75 m to 1.8 given in the literature surveyed. It is noticed the mismatch of internal conditions with thermal comfort, and indoor air quality recommended by [ASHRAE Standard 62, ANSI / ASHRAE Standard 55-2010]. CFD simulations have been carried to provide insights on the indoor air quality and comfort conditions throughout the classroom. Particle concentrations, thermal conditions, and modified ventilation system solutions are reported.

Modeling the Applicability of a Displacement Ventilation System

2021 ◽  
Vol 11 (1) ◽  
pp. 63-89
Author(s):  
Edgar C. Ambos ◽  
Evan Neil V. Ambos ◽  
Lanndon A. Ocampo
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Heat Load ◽  
Ventilation System ◽  
Internal Heat ◽  
The Philippines ◽  
Airflow Rate ◽  
Displacement Ventilation ◽  
Tropical Country

Due to its significant role in improving indoor air quality, displacement ventilation system is widely adopted in current literature. This paper proposes a displacement ventilation system for room conditions with ceilings that are relatively low, internal heat load could be high, walls could be sunlit, and occupants doing the low physical activity. These conditions are prevalent in the Philippines, being a tropical country. Input parameters to the design process such as heat load, the height of the ceiling, comfort, and indoor air quality requirements were generated, and the main output parameters are the stratification height and ventilation airflow rate. To demonstrate the proposed displacement ventilation system, four cases were generated. Results show that the ventilation airflow rates obtained from the four cases were greater than the minimum outdoor air requirements for health in conference rooms and large assembly areas which are 17.5 and 3.5 liters/sec*person respectively, for smoking and no smoking rooms.

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

2020 ◽  
pp. 65-74
Author(s):  
Eusébio Conceição ◽  
Mª Inês Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Numerical Model ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Ventilation System ◽  
Airflow Rate ◽  
Hvac System ◽  
Personalized Ventilation

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

A Study on the Evaluation of Ventilation Performance According to the Location of the Return Diffusers of an Upward Displacement Ventilation System in a Dome-Shaped Small Concert Hall

2019 ◽  
Vol 27 (03) ◽  
pp. 1950028
Author(s):  
Yong-Il Kwon
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Vertical Wall ◽  
High Energy ◽  
Displacement Ventilation ◽  
Concert Hall ◽  
Upward Displacement ◽  
Ventilation Performance

The modern people are active in various cultural facilities and enjoy the leisure life. The spectators and performers using a small concert hall generally use this space for about 2[Formula: see text]h in an enclosed state, and so the space should maintain a comfortable thermal environment and indoor air quality. The ventilation systems that can be applied to small concert hall are generally classified as the mixing ventilation system and the displacement ventilation system, but the upward displacement ventilation system is known to be able to maintain the clean indoor air quality with high energy efficiency. The upward displacement ventilation system installed in a dome-shaped small concert hall is not limited in the height of the vertical wall. Therefore, it is necessary to evaluate the optimal height of the return diffuser by utilizing the ventilation performance and the air diffusion performance index (ADPI). This study was carried out to evaluate the effect of the return diffuser position on the ventilation performance of an upward displacement ventilation system installed in a dome-shaped small concert hall. It was confirmed that as the height at which the return diffuser is installed on the vertical wall increases, the ventilation efficiency increases and the thermal stratification formed in the upper area is significantly reduced.

Measurement and Simulation of Indoor Air Quality and CO2 Concentration in a Hotel Room

2010 ◽  
Author(s):  
Ehsan Asadi ◽  
Manuel Gameiro da Silva ◽  
Jose´ J. Costa
Keyword(s):  
Air Quality ◽  
Simulation Model ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Co2 Concentration ◽  
Simulation Software ◽  
Building Simulation ◽  
Airflow Rate ◽  
Air Exchange Rate ◽  
Ventilation Performance

Indoor air quality (IAQ) is nowadays universally recognized as an important issue that affects the comfort and health of people, as well as their productivity. This paper describes the relationship of indoor CO2 concentration to building air quality and ventilation, with a focus on how CO2 can be used to evaluate and predict air quality and ventilation performance, namely the infiltration airflow rate. Besides it shows the ability of ESP-r building simulation software for predicting the CO2 concentration and the air exchange rate in a building. For this purposes a room of a hotel located in the urban area of Coimbra was chosen. The developed simulation model was then validated against empirical results. It was shown that a fair degree of agreement between ESP-r results and the experimental observation exist for the zones. High accuracy of the simulation model showed that building simulation software, namely ESP-r can provide a better understanding of indoor environmental conditions and be a powerful tool in finding the best modification measures for improving the indoor air quality in a building.

scholarly journals Computational Analysis of a Lecture Room Ventilation System

2020 ◽  
Author(s):  
Abayomi Layeni ◽  
Collins Nwaokocha ◽  
Olalekan Olamide ◽  
Solomon Giwa ◽  
Samuel Tongo ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Minimum Cost ◽  
Solar Chimney ◽  
Lecture Room ◽  
Room Ventilation System ◽  
Ventilation Systems

The level of Indoor Air Quality (IAQ) has become a big topic of research, and improving it using passive ventilation methods is imperative due to the cost saving potentials. Designing lecture buildings to use less energy or Zero Energy (ZE) has become more important, and analysing buildings before construction can save money in design changes. This research analyses the performance (thermal comfort [TC]) of a lecture room, investigate the use of passive ventilation methods and determine the energy-saving potential of the proposed passive ventilation method using Computational Fluid Dynamics (CFD). Results obtained showed that air change per hour at a wind velocity of 0.05 m/s was 3.10, which was below standards. Therefore, the lecture hall needs external passive ventilation systems (Solar Chimney [SC]) for improved indoor air quality at minimum cost. Also, it was observed that the proposed passive ventilation (SC) system with the size between 1 and 100 m3, made an improvement upon the natural ventilation in the room. There was a 66.69% increase after 10 years in the saving of energy and cost using Solar Chimney as compared to Fans, which depicts that truly energy and cost were saved using passive ventilation systems rather than mechanical ventilation systems.

scholarly journals Air Ventilation Performance of School Classrooms with Respect to the Installation Positions of Return Duct

2021 ◽  
Vol 13 (11) ◽  
pp. 6188
Author(s):  
Sungwan Son ◽  
Choon-Man Jang
Keyword(s):  
Air Quality ◽  
Numerical Analysis ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Three Dimensional ◽  
Cross Infection ◽  
School Students ◽  
Height Range ◽  
Air Ventilation ◽  
Ventilation Performance

For students, who spend most of their time in school classrooms, it is important to maintain indoor air quality (IAQ) to ensure a comfortable and healthy life. Recently, the ventilation performance for indoor air quality in elementary schools has emerged as an important social issue due to the increase in the number of days of continuous high concentrations of particulate matter. Three-dimensional numerical analysis has been introduced to evaluate the indoor airflow according to the installation location of return diffusers. Considering the possibility of the cross-infection of infectious diseases between students due to the direction of airflow in the classroom, the airflow angles of the average respiratory height range of elementary school students, between 1.0 and 1.5 m, are analyzed. Throughout the numerical analysis inside the classroom, it is found that the floor return system reduces the indoor horizontal airflow that causes cross-infection among students by 20% compared to the upper return systems. Air ventilation performance is also analyzed in detail using the results of numerical simulation, including streamlines, temperature and the age of air.

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