A Numerical Model of Carbon Dioxide Concentration Measurement in a Room with an Opened Ventilation System

A method for controlling the ventilation system flow characteristics is considered based on the forming principle an air temperature and carbon dioxide concentration predicted estimate in a room based on the changes dynamics analysis in these parameters in the supply and exhaust ducts. The expected microclimate parameters predicted assessment in real time opens up the possibility of using such elements and algorithms for controlling the ventilation and air conditioning system, which provide the required air quality with minimal energy consumption. The analysis calculates the finding probability the measured parameter inside or outside the control zone after a specified time interval. The algorithm for the control system actuators actuation for the channels of temperature and carbon dioxide concentration is presented in the block diagram form. The decision-making logic for actuating the actuators is based on the changes direction and intensity analysis in temperature and carbon dioxide concentration in the exhaust duct and the temperature difference between the supply and exhaust

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Simulation and Analysis of Various Ventilation Systems Given in an Example in the Same School of Indoor Air Quality

Energies ◽

10.3390/en12152845 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2845 ◽

Cited By ~ 2

Author(s):

Katarzyna Gładyszewska-Fiedoruk ◽

Vasyl Zhelykh ◽

Andrii Pushchinskyi

Keyword(s):

Carbon Dioxide ◽

Air Quality ◽

Natural Ventilation ◽

Ventilation System ◽

Carbon Dioxide Concentration ◽

Additional Energy ◽

Exhaust Ventilation ◽

Building Ventilation ◽

The Cost

The quality of internal air is one of the factors that affect the pace and quality of knowledge acquisition. Therefore, it is important that classrooms have high quality of air. Using computer simulation, the effect of various building ventilation variants on air quality in classrooms was analyzed. Two criteria were analyzed and six variants of ventilation. The analysis was carried out using the CONTAMW program, used for multi-zone analysis of ventilation and air quality in a building. As an indicator of air quality, the concentration of carbon dioxide in school halls was adopted. The analyses show that natural ventilation is not able to provide proper air exchange. Regular airing of classrooms during breaks can reduce the carbon dioxide concentration to 2500 ppm, however, there is a significant reduction in indoor temperature (even below 10 °C). The best control over the internal environment can be obtained by using a supply–exhaust ventilation system with heat recovery. Obtaining a higher stabilization of ventilation is achieved by supplying additional energy to drive fans, however, this is only a small amount of energy compared to the cost of heat for heating the building (maximum 2%).

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Indoor Air Quality Assessment in a Single-Family House Equipped with Demand Controlled Mechanical Ventilation

Ecological Chemistry and Engineering S ◽

10.2478/eces-2020-0025 ◽

2020 ◽

Vol 27 (3) ◽

pp. 387-402

Author(s):

Jarosław Müller ◽

Maciej Dębowski

Keyword(s):

Carbon Dioxide ◽

Mechanical Ventilation ◽

Meteorological Data ◽

Ventilation System ◽

Operating Cost ◽

Carbon Dioxide Concentration ◽

Contamination Level ◽

Internal Source ◽

Single Family ◽

Family House

AbstractThe paper presents the results of modelling airflow for ventilation of a single-family house with an area of 180 m2. The building was equipped with mechanical ventilation with the possibility of varying the airflow. The airflow was calculated as a function of carbon dioxide concentration. The presence of people in selected rooms was an internal source of carbon dioxide. In order to properly design of a ventilation system and then model the contamination level, ContamW software was used. The year-long cost analysis was carried out for the installation working with variable airflow (day, night). The analysis took into account the price of the electricity used by the fans of Air Handling Unit and meteorological data to estimate the power input to the heater of the Unit. Different scenarios of system operation were included as an input data in order to find a difference in energy consumption. The calculations were to answer the question of whether it is necessary to apply expensive and advanced system that enables individual control of the airflow in every room or use the simple control of the central unit to vary the airflow in the ventilation system of single-family houses. The difference in operating cost between the system that maintains 800 and 600 ppm reaches 100 % and demonstrates the need of simple demand controlled ventilation system.

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Numerical Model Development of the Air Temperature Variation in a Room Set on Fire for Different Ventilation Scenarios

Applied Sciences ◽

10.3390/app112411698 ◽

2021 ◽

Vol 11 (24) ◽

pp. 11698

Author(s):

Marius Dorin Lulea ◽

Vlad Iordache ◽

Ilinca Năstase

Keyword(s):

Numerical Model ◽

Air Temperature ◽

Residential Buildings ◽

Ventilation System ◽

Model Development ◽

Carbon Dioxide Concentration ◽

Sprinkler System ◽

Rate Variation ◽

Cfd Model ◽

Specific Point

Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements’ dimensions, burner heat release rate variation) were imposed to the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model. Besides the air temperature, at this point, other essential parameters were determined in the entire experimental space: indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. We found that if the ventilation rate increases, the indoor temperatures in that specific point decrease, and the sprinkler is activated later or, in some cases, it might never be activated. However, this conclusion is not valid for the entire analyzed space, as the ventilation system alongside the natural air movement imposes specific air speed and specific temperature distribution inside the analyzed space.

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Communication: Photoinduced Carbon Dioxide Binding with Surface-Functionalized Silicon Quantum Dots

10.26434/chemrxiv.5944273.v1 ◽

2018 ◽

Author(s):

Oscar A. Douglas-Gallardo ◽

Cristián Gabriel Sánchez ◽

Esteban Vöhringer-Martinez

Keyword(s):

Carbon Dioxide ◽

Quantum Dots ◽

Atmospheric Carbon Dioxide ◽

Density Functional ◽

Tight Binding ◽

Carbon Dioxide Concentration ◽

Research Area ◽

Silicon Quantum Dots ◽

Dependent Model ◽

Photoinduced Charge

<div> <div> <div> <p>Nowadays, the search of efficient methods able to reduce the high atmospheric carbon dioxide concentration has turned into a very dynamic research area. Several environmental problems have been closely associated with the high atmospheric level of this greenhouse gas. Here, a novel system based on the use of surface-functionalized silicon quantum dots (sf -SiQDs) is theoretically proposed as a versatile device to bind carbon dioxide. Within this approach, carbon dioxide trapping is modulated by a photoinduced charge redistribution between the capping molecule and the silicon quantum dots (SiQDs). Chemical and electronic properties of the proposed SiQDs have been studied with Density Functional Theory (DFT) and Density Functional Tight-Binding (DFTB) approach along with a Time-Dependent model based on the DFTB (TD-DFTB) framework. To the best of our knowledge, this is the first report that proposes and explores the potential application of a versatile and friendly device based on the use of sf -SiQDs for photochemically activated carbon dioxide fixation. </p> </div> </div> </div>

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