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 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 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.

Enhancement of Gravity Ventilation in Buildings

2017 ◽  
Author(s):  
Magdalena Nakielska ◽  
Krzysztof Pawłowski
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Electrical Energy ◽  
Climatic Conditions ◽  
Demand Systems ◽  
Solar Chimney ◽  
Correct Operation ◽  
Research Results ◽  
Heat Demand ◽  
Flow Through

Nowadays, people are looking for solutions related to ventilation, cooling or heat demand systems, which would be energy efficient and, at the same time, would not cause the degradation of the surrounding environment. As far as ventilation is concerned, an good solution is a natural ventilation, which improves thermal comfort rooms without increasing the consumption of electrical energy in the building. In order to improve the mode of action of the natural ventilation in the building, one can mount various elements supporting the air flow. One of them is a solar chimney. In order to check the correct operation of a gravity ventilation installation in Poland’s climatic conditions, the measurements was carried out on a test stand on the 3.1 building of UTP University of Science and Technology in Bydgoszcz. The received results show the intensification of the air flow through the room the value between 50% and 150%, depending on a measuring hour (Chen et al. 2003). These research results were compared with the research results received before the installation of the solar chimney on the ducts of the gravity ventilation.

Air Flow Modelling of a Multi-Storey Office Building

2013 ◽  
Vol 361-363 ◽  
pp. 833-844
Author(s):  
Chong Jie Wang ◽  
Wei Wei Liu
Keyword(s):  
Temperature Distribution ◽  
Natural Ventilation ◽  
Air Flow ◽  
Comfort Level ◽  
Office Building ◽  
Temperature Stratification ◽  
Air Distribution ◽  
Flow Modelling ◽  
Ventilation Strategies

Indoor fresh air distribution, temperature stratification and temperature distribution are consider to be the essential indicators when comes to evaluation of the comfort level for internal ventilation environment, particularly for natural ventilated space as target office building. It can be identified that the targeting building has been well designed in the respect of natural ventilation strategies where both cross and stack strategies have been adopted, but it is also obvious that under combined buoyancy and wind driven mode alternative problems appears.

Three Dimensional Simulation of Ventilation Flow Through a Solar Windcatcher

2019 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation System ◽  
Three Dimensional ◽  
Windward Side ◽  
Efficient Design ◽  
Indoor Space ◽  
Wind Speeds ◽  
Air Stream ◽  
Stack Ventilation

Abstract Natural ventilation is the process of supplying and removing air through an indoor space by natural means. There are two types of natural ventilation occurring in buildings: winddriven ventilation and buoyancy driven or stack ventilation. The most efficient design for natural ventilation in buildings should implement both types of natural ventilation. Stack ventilation which is temperature induced is driven by buoyancy making it less dependent on wind and its direction. Heat emitted causes a temperature difference between two adjoining volumes of air, the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. Combining the wind driven and the buoyancy driven ventilation will be investigated in this study through the use of a windcatcher natural ventilation system. Stack driven air rises as it leaves the windcatcher and it is replaced with fresh air from outside as it enters through the positively pressured windward side. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the winddriven ventilation alone, buoyancy driven ventilation alone, and combined buoyancy and winddriven ventilation. Different wind speeds between 0 up to 2.5 m/s are applied and the total air flow rate through the windcatcher is investigated with and without temperature of 350 K applied at the windcatcher’s outlet wall. As the wind speed increased the efficiency of the solar windcatcher decreased.

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 Design Methodology for Street-Oriented Block Housing Considering Daylight and Natural Ventilation

2018 ◽  
Vol 10 (9) ◽  
pp. 3154 ◽  
Author(s):  
Ho-Jeong Kim ◽  
Jin-Soo Kim
Keyword(s):  
Path Planning ◽  
Design Methodology ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Air Flow ◽  
Small Scale ◽  
Exterior Space ◽  
Housing Design ◽  
Continuous Access ◽  
Prevailing Wind Direction

This study presents a design methodology for street-oriented block housing, as a model for gradual small-scale block-unit development, that can secure two hours of continuous access to daylight on the winter solstice at azimuth angles of 0° and 60° in Seoul, South Korea, and, in addition, developed a methodology for wind path planning for existing types of developed housing. The results of this study have confirmed the feasibility of a housing design that can secure two hours of continuous access to daylight along with no less than 200 percent of development density, achieved through the elimination of self-shadows by using distances between residential buildings and shadow characteristics according to azimuth angles. In addition, the study identified an air flow stagnation section by assessing the air flow of the exterior space of street-oriented block housing in consideration of day-lit environments, and examined a planning model that can enhance natural ventilation potential by activating the air flow of the exterior space. Wind path planning was conducted for 24 alternatives that were produced based on the developed design methodology, and the wind velocity ratio of street-oriented block housing ranged from 0.34 to 0.59. In terms of disadvantages of street-oriented block housing in securing wind paths, this study confirmed that air flow could be strengthened by adjusting the form of the lower-part opening, which is open in the direction of incoming wind, designing a staggered mass layout in high-rise masses, and combining building floor heights. The above findings of this study suggest that a performance-based approach is necessary for the improvement of environmental performance in street-oriented block housing, in consideration of azimuth angles and the prevailing wind direction from the initial phase of planning.

scholarly journals Influence of Wind on Air Movement in a Free-Stall Barn During the Summer Period / Wpływ wiatru na ruch powietrza w oborze wolnostanowiskowej w okresie letnim

2013 ◽  
Vol 13 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Piotr Herbut ◽  
Sabina Angrecka ◽  
Grzegorz Nawalany
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation System ◽  
Air Velocity ◽  
Summer Period ◽  
Air Masses ◽  
Air Movement ◽  
Microclimatic Conditions ◽  
Hot Weather ◽  
Different Levels

Abstract Use of natural ventilation in the barn should lead to optimal microclimatic conditions over the entire space. In the summer, especially during hot weather, higher air velocity cools cows, which helps to avoid heat stress. The paper presents the results of studies on the evolution of air movement in a modernized free-stall barn of the Fermbet type with the natural ventilation system during the summer period. Based on measurements of velocity and direction of air flow (inside and outside the barn) and observations of smoke indicator, the movement of air masses in different parts of the barn was identified. Significant variations of air flow at different levels of the barn were found. These differences deviate from the accepted patterns of natural ventilation, which can be found in the literature. The range of a draught and stagnant air along with the conditions in which they are built was determined. On this basis, recommendations regarding the location of barns on the plots and the improvement of ventilation in summer were made.

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.

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