scholarly journals Living quarters. A natural balanced ventilation system. Simulations part 1

2018 ◽  
Vol 49 ◽  
pp. 00025 ◽  
Author(s):  
Tomasz Gaczoł
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Comfort Level ◽  
Test Results ◽  
Pressure System ◽  
Ansys Fluent ◽  
Short Supply ◽  
Air Exchange Rate ◽  
Exhaust Duct

In the following article the author proposes the solution for a properly functioning natural ventilation system based on the use of supply and exhaust ducts, i.e. by designing a natural balanced ventilation system. The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the lower floor of the building. The simulations conducted in ANSYS Fluent software relate to such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of airflow through supplyexhaust ducts and in the analysed room. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney”. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. In the era of common building sealing, the presented ventilation system may be a good solution that guarantees proper functioning of natural ventilation. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (first part) describes test results concerning the room located on the lower floor of the building, i.e. with a short supply duct and a 12-meter long exhaust duct.

scholarly journals Natural balanced ventilation. Simulations part 2

2018 ◽  
Vol 49 ◽  
pp. 00026
Author(s):  
Tomasz Gaczoł
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Air Flow ◽  
Ventilation System ◽  
Flow Analysis ◽  
Comfort Level ◽  
Test Results ◽  
Pressure System ◽  
Exhaust Duct ◽  
Flow Through

The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the upper floor of the building that were conducted in ANSYS Fluent software. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney” that is usually a glass superstructure, located on the roof of the building above the ventilation ducts. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. The simulations concerned such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of air flow through supply and exhaust ducts and in the room. Tests conducted using a computer method of air flow analysis in ducts and in the analysed room indicate that the developed natural balanced ventilation system is a good solution, especially when building sealing is so common. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (second part) describes test results concerning the room located on the upper floor of the building, i.e. with a long 9-meter long supply duct and a short 3-meter long exhaust duct.

scholarly journals ANALYSIS OF AIR FLOW DISTRIBUTION IN RESIDENTIAL ROOMS WITH SUPPLY WINDOW VALVES BY MATHEMATICAL MODELING IN ANSYS FLUENT

2019 ◽  
Vol 4 (10) ◽  
pp. 67-73
Author(s):  
О. Симбирев ◽  
O. Simbirev
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Flow Distribution ◽  
Ansys Fluent ◽  
Airflow Distribution ◽  
Standard Values ◽  
Technical Solutions

The main problem highlighted in the article is the deviation of the microclimate parameters from the standard values due to the improper organization of airflow in the residential rooms of apartment buildings. The objective is to obtain a working mathematical model of the natural ventilation system, its study for optimization or modernization. The analysis of the normative literature, scientific works of domestic and foreign scientists, developments in the field of natural ventilation and ventilation of residential buildings is carried out. A mathematical model of air exchange of a residential room with convection is presented and analyzed. The flow rate and air temperature, the temperature on the surface of the heater are set as boundary conditions when creating a mathematical model. The features and regularities of airflow distribution in the room obtained as a result of mathematical modeling are revealed. The distributions of air velocity in the room are given. Difficulties of the organization of effective natural inflow of air and the problems with design of valves of infiltration are designated. Technical solutions aimed at improving the quality of indoor microclimate and energy saving are proposed.

scholarly journals Evaluation of Thermal Comfort in the Traditional Bourgeoisie Houses in Beirut

2020 ◽  
Vol 3 (1) ◽  
pp. p1
Author(s):  
Jad Hammoud ◽  
Elise Abi Rached
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Heat Waves ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Electricity Consumption ◽  
Comfort Level ◽  
Climate Zones

The increasing of energy demands has considerably increased the requirements for new and traditional buildings in different climate zones. Unprecedented heat waves have increased climate temperature, in particular, in moderate climate zones such as Lebanon. In Beirut, only the residential sector consumes 50% of total electricity consumption. HVAC (Heating, Ventilation and Air conditioning) systems are used to reach acceptable thermal comfort levels in the new residential buildings. In case of the traditional bourgeoisie houses in Beirut, there are no discussions about the use of HVAC systems to achieve the required thermal comfort level. Thus, to reach an acceptable thermal comfort level, these houses which already contain natural ventilation system shall adapt the modern thermal comfort requirements and thermal comfort strategies and technologies where their architectural features and existing materials condition the available solutions. In order to identify the best options within the possible intervention lines (envelopes, passive strategies, equipment, renewable energy systems), it is necessary to perceive the real performance of this type of houses. In this context, the article presents the results of the study of thermal performance and comfort in a three case studies located in Beirut. Detailed field data records collected are analyzed, with a view to identify the indoor thermal environment with respect to outdoor thermal environment in different seasons. Monitoring also included measurement of hygrothermal parameters and surveys of occupant thermal sensation.

scholarly journals The negative and positive pressure system of natural balanced ventilation

2020 ◽  
pp. 1-10
Author(s):  
Tomasz Gaczoł
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Positive Pressure ◽  
Pressure System ◽  
Ansys Fluent ◽  
Exhaust Duct ◽  
Basement Floor ◽  
Air Intake ◽  
Flow Through ◽  
Vector Direction

This paper discusses the results of research conducted with the Ansys Fluent programme on the air flow through natural ventilation supply and exhaust ducts of rooms located on the ground and upper floor of a building. A scenario with air inflow to a room through an air intake located on the basement floor level was selected for the tests. All simulations were performed for outdoor temperatures of +3,+12, and -15°C (simulations run for an outdoor air temperature of +12°C are discussed in detail). The temperature inside the room is +20°C, i.e. at the minimum temperature level for thermal comfort. The simulations address such issues as the pressure system inside the room and in the exhaust duct, the distribution of air temperature in the room and the vector direction of airflow through the supply and exhaust ducts.

scholarly journals Three-Dimensional Simulation of Wind-Driven Ventilation Through a Windcatcher With Different Inlet Designs

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. Phuoc Huynh
Keyword(s):  
Wind Speed ◽  
Average Velocity ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Wind Velocities ◽  
Dimensional Simulation ◽  
Convergent Inlet

Abstract Windcatcher is an effective natural ventilation system, and its performance depends on several factors including wind speed and wind direction. It provides a comfortable and healthy indoor environment since the introduced fresh air decreases the moisture content and reduces the pollutant concentration. Since the wind speed and its direction are generally unpredictable, it is important to use special inlet forms and exits to increase the efficiency of a windcatcher. In this study, computational fluid dynamics (CFD) modeling is implemented using ansys fluent to investigate the airflow entering a three-dimensional room through a windcatcher with different inlet designs. Three designs are studied which are a uniform inlet, a divergent inlet, and a bulging-convergent inlet. The airflow pattern with all inlets provided adequate ventilation through the room. With all the applied wind velocities (1, 2, 3, and 6 m/s) at the domain's inlet, the divergent inlet shape has captured the highest airflow through the room and provided higher average velocity at 1.2 m high enhancing the thermal comfort where most of the human occupancy occurs. With 6 m/s wind velocity, the divergent inlet has captured 2.55% more flow rate compared to the uniform inlet and 4.70% compared to the bulging-convergent inlet, and it has also provided an average velocity at 1.2 m high in the room of 7.16% higher than the uniform inlet and 8.44% higher than the bulging-convergent inlet.

Numerical analysis of local thermal comfort in a plan office under natural ventilation

2019 ◽  
Vol 29 (7) ◽  
pp. 972-986 ◽  
Author(s):  
Xiang Deng ◽  
Zijing Tan
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Meteorological Data ◽  
Ventilation System ◽  
Comfort Level ◽  
Open Plan ◽  
Computational Fluid Dynamics Cfd ◽  
Internal Volume ◽  
Local Thermal Comfort ◽  
Primary Focus

The utilisation of automatic controlled natural wind in office buildings to maintain indoor thermal comfort has gained wide attention in recent years. Generally, it is not necessary to ensure that the whole internal volume of a building with large open spaces meets thermal comfort requirements. Primary focus should be on occupied areas. Accordingly, the local thermal comfort in an open-plan office with automatic controlled natural ventilation system was investigated numerically and experimentally. A computational fluid dynamics (CFD)-based method was presented for indoor environment and thermal comfort prediction. Long-term in situ measurement was conducted during summer and transition seasons. The meteorological data were collected by a mini weather station located on the roof of the target building. Meanwhile, indoor air velocity, temperature, turbulence intensity and wall temperatures were recorded locally. Three thermal comfort indices, i.e. thermal stratification represented by percentage dissatisfied (PD), the extended predicted mean vote (PMVe) and draught rate were employed to evaluate the thermal comfort level of the interested areas during natural ventilation period. The numerical results revealed a risk of local thermal dissatisfaction under low outdoor temperature and strong windy conditions.

scholarly journals The Influence of the Permeability of the Fractures Zone Around the Heading on the Concentration and Distribution of Methane

2019 ◽  
Vol 12 (1) ◽  
pp. 16 ◽  
Author(s):  
Magdalena Tutak
Keyword(s):  
Ventilation System ◽  
Organizational Factors ◽  
Primary Objective ◽  
Test Results ◽  
Ansys Fluent ◽  
New Approach ◽  
Model Based ◽  
Coal Beds ◽  
Air Stream ◽  
Fluent Software

One of the main problems related to the excavation of dog headings in coal beds is the emission of methane during this process. To prevent the occurrence of dangerous concentration levels of this gas, it is necessary to use an appropriate ventilation system. The operation effectiveness of such a system depends on a number of mining, geological, technical and organizational factors. One of them includes the size and permeability of the fractures zone formed around the excavated dog heading. The primary objective of the paper is to determine the influence of this zone on the ventilation parameters, including the concentration and distribution of methane in the excavated dog heading. In order to achieve the assumed objective, multivariate model-based tests were carried out, which reproduce a real-world dog heading. Literature data and test results in actual conditions were used to determine the size and permeability of the fractures zone around the excavated heading. These data served as the basis to develop a model of the region under analysis and adopt boundary conditions. The analyses were carried out for four permeability values of the fractures zone and for two volumetric flow rates of the air stream supplied to the heading. The results were used to determine the influence of the fractures zone on the distribution and concentration of methane in the heading under analysis. The model-based tests were performed using ANSYS Fluent software. The idea to take into account the fractures zone around the heading represents a new approach to the analysis of ventilation parameters in underground mine headings. The results clearly indicate that this zone affects the ventilation parameters in the heading, including the distribution and concentration of methane. The knowledge obtained from the tests should be used to optimize the ventilation process of dog headings. All authors have read and agreed to the published version of the manuscript.

scholarly journals Air Exchange Rate in Air Quality Assurance – A Case Study

2018 ◽  
Vol 8 (1) ◽  
pp. 13-18
Author(s):  
I. L. Cîrstolovean ◽  
M. Horneț ◽  
Ana Diana Ancas ◽  
M. Profire
Keyword(s):  
Exchange Rate ◽  
Air Quality ◽  
Heat Load ◽  
Natural Ventilation ◽  
Mechanical Energy ◽  
Ventilation System ◽  
Time Interval ◽  
Indoor Temperature ◽  
Air Exchange Rate ◽  
Air Exchange

Abstract The goals of this paper are to estimate some parameters – indoor temperature and ventilation rate - necessary to determine the heat load demand for ventilation in the amphitheatre named ‘A TALPOSI’-Faculty of Buildings Engineering- with a number of at the most 120 occupants. The study presented in this paper is made when in the amphitheatre it is necessary to assure a comfortable temperature by a permanent functioning of the heating system. The number of air exchanges necessary in the amphitheatre in the natural ventilation process, more exactly, to assure a minimum air exchanges, is imposed by the requirements for the assurance of physiologic comfort in the amphitheatre for the time interval when it is occupied by students. The inner air debit should cover the harmful emissions in the amphitheatre. By the help of these calculated (measured) parameters we have calculated the heat load for ventilation. In the end, with the data obtained from calculations and measurements we find ourselves in the situation of establishing the size of the heat exchanger corresponding to the room, to heat the fresh air taken from outside and send it inside the amphitheatre. The measurements are made with the TESTO apparatus of the faculty. The minimum requirements to assure the thermal comfort are: to achieve a minimum internal temperature θi (t) higher than (or equal to) the normal indoor temperature associated to this space and to assure the air quality, the air exchange rate. The authors want to highlight by this study the necessity and importance of the control on the number of air exchanges in rooms with a high number of occupants and overall, the control of the fresh air debits. The fact that the focus is more and more on heat loss cuts in rooms by tightening closing elements gives birth to the necessity of control of the ventilation system with effects on the consumption of mechanical energy.

scholarly journals Simulation of Naturally Ventilated Underground Car Park with CFD

2020 ◽  
Vol 3 (SI3) ◽  
pp. SI22-SI28
Author(s):  
Huong Mai Thi Nguyen ◽  
Trương Tích Thiện
Keyword(s):  
Fire Safety ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Urban Land ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Car Park ◽  
Effective Ventilation ◽  
Fire And Explosion ◽  
Cfd Method

Nowadays, the speed of urbanization is increasing rapidly, so the urban land area is fully utilized to build high-rise buildings, apartments, and commercial centers, and thus, the car tunnel parking and basement parking basements also become more popular. However, apartment fire and explosion, especially car fire and explosion is an extremely important issue that must be concerned in construction design. Therefore, it is essential to design an effective ventilation system in the parking basement when a fire occurs an effective ventilation system for the tunnel is really necessary for basement firefighting. When building up the car park, the importance is not only a reasonable architecture but also the ventilation and air quality of the tunnel because it directly affects human health. Decades ago, scientists had studied the solution to ventilate the car park. The computational fluid dynamics (CFD) method is also applied to determine the pressure and velocity intensity for buildings that detect residuals in architecture, thereby improving and providing a superior solution. More for this problem. Many studies related to this issue have been published internationally. Jiang (Jiang, Allocca, & Chen, 2004) also investigated natural ventilation by using Reynolds Averaged Navier - Stokes turbulence model (RANS). Khalil (Khalil, Shoukry, H.A, & Harridy, 2015) also examined the distribution of CO emissions from buses in a basement in Cairo using ANSYS FLUENT software.The basement car park is a popular solution to effectively use urban land, especially in commercial centers and apartments. However, the situation of apartment fire and explosion is a hot problem, partly due to the tunnel ventilation has not met the requirements of fire safety. Therefore, the design of the car park basement ensures fire safety as well as bring comfort to people. In this study, the problem of basement temperature and wind velocity by natural ventilation method will be analyzed and evaluated in accordance with ADPI standard and Carbon monoxide concentration with WHO standard to identify areas of unsatisfactory temperature and velocity to reasonably adjust and propose other suitable ventilation options.

scholarly journals Investigation of Ventilation Behaviors in Mechanically Ventilated Residential Buildings in China

2019 ◽  
Vol 111 ◽  
pp. 06048
Author(s):  
Yue Qi ◽  
Junjie Liu ◽  
Xilei Dai ◽  
Lei Zhao ◽  
Dayi Lai ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Energy Efficient ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Outdoor Air ◽  
Climate Zones ◽  
Mechanically Ventilated ◽  
Ventilation Duration ◽  
Site Monitoring

Mechanical ventilation system provides a more reliable, controllable, and comfortable way of ventilation than natural ventilation through an opened window. However, the operation of mechanical ventilation system cost energy. This study investigated the usage of natural and mechanical ventilation in 46 apartments in ten cities across five different climate zones in China by on-site monitoring and questionnaire survey. On average, the daily natural and mechanical ventilation durations were 11 hours and 7.2 hours, respectively. Large differences existed among climate regions and seasons. From north to south, as the climate became warmer, the usage of natural ventilation increased. From seasonal perspectives, natural ventilation duration was the longest in summer and the shortest in winter. The trend of mechanical ventilation usage was opposite to that of natural ventilation. Generally, as the outdoor air temperature increased, the duration of natural ventilation increased and the duration of mechanical ventilation decreased. This study proposed an outline to use thermal comfort, health, and energy saving as three motivations to analyze ventilation behaviors. Based on the obtained results, suggestions were made for achieving healthy, thermally comfortable, and energy efficient ventilation in residential buildings.

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