scholarly journals Improvement of the Chimney Effect in Stack Ventilation

2021 ◽  
Vol 11 (19) ◽  
pp. 9185
Author(s):  
Romana Antczak-Jarząbska ◽  
Krzysztof Pawłowski ◽  
Maciej Niedostatkiewicz
Keyword(s):  
Natural Ventilation ◽  
Ventilation System ◽  
Common Denominator ◽  
Air Inlet ◽  
Transparent Barrier ◽  
Scale Experiment ◽  
Stack Ventilation ◽  
Chimney Effect ◽  
Rotary Type ◽  
Made In

The article is focused on the airflow in a ventilation system in a building. The work examines the methods which enhance the chimney effect. In this paper, three cases with different chimneys were analyzed for the full-scale experiment. These cases were characterized by different geometrical and material parameters, leading to differences in the intensity of the ventilation airflow. The common denominator of the cases was the room with the air inlet and outlet to the ventilation system. The differences between the experimental cases concerned the chimney canal itself, and more precisely its part protruding above the roof slope. The first experimental case concerned a ventilation canal made in a traditional way, from solid ceramic brick. The second experimental case concerned the part that led out above the roof slope with a transparent barrier, called a solar chimney. In the third experimental case, a rotary type of chimney cap was installed on the chimney to improve the efficiency of stack ventilation. All these cases were used to determine the performance of natural ventilation—Air Change per Hour (CH). Additionally, the paper presents a technical and economic comparison of the solutions used.

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.

scholarly journals Application of the Chimney Cap as a Method of Improving the Effectiveness of Natural Ventilation in Buildings

2020 ◽  
Vol 27 (3) ◽  
pp. 168-175
Author(s):  
Romana Antczak-Jarząbska ◽  
Maciej Niedostatkiewicz
Keyword(s):  
Natural Ventilation ◽  
Transition Period ◽  
Physical Phenomenon ◽  
Ventilation System ◽  
Cost Savings ◽  
Change Rate ◽  
Indoor Pollutants ◽  
Air Change Rate ◽  
Chimney Effect

AbstractAdequately designed natural ventilation is the cheapest and easiest way to effectively remove indoor pollutants and keep the air inside a building fresh. A prediction of the performance and effectiveness of ventilation in order to determine the design of a ventilation system can provide real and long-term cost savings. The worst time in terms of the efficiency of natural ventilation is the spring-autumn transition period [7]. In order to improve the efficiency of natural ventilation, chimney caps are used, among others. They are designed to improve the chimney effect described in colloquial language as a chimney draft. The chimney effect is a physical phenomenon of the formation of a spontaneous flow of a warmer gas, e.g. air, from the bottom up in stem channels [12]. The article analyses the influence of the chimney cowl on the improvement of the chimney effect in an apartment of a multi-family building with natural ventilation. Long-term tests of the chimney draft were carried out for the case without and with a chimney cap. The paper presents the results of the performance (air change rate, ACH) of natural ventilation for a building with an inlet gap measured for the transitional season (between the heating and the summer season). The measurements were performed during a windy period.

Effect of Combining Buoyancy Driven and Winddriven Ventilation in a Two Dimensional Room Fitted With a Windcatcher

2017 ◽  
Author(s):  
Peter Abdo ◽  
B. P. Huynh
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Windward Side ◽  
Two Dimensional ◽  
Efficient Design ◽  
Indoor Space ◽  
Air Stream ◽  
Stack Ventilation ◽  
Natural Means

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 ventilation, 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 winddriven 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 two dimensional room fitted with a windcatcher based on the winddriven ventilation alone and on the combined buoyancy and winddriven ventilation.

scholarly journals Application of Ventilation Technology of Bamboo Houses in Modern High-Rise Buildings

2020 ◽  
Vol 2 (2) ◽  
pp. 42
Author(s):  
Zijie Zhou ◽  
Yiqiang Xiao
Keyword(s):  
Power Plant ◽  
Experimental Method ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Office Building ◽  
Actual Measurement ◽  
High Rise ◽  
Air Inlet ◽  
Humid Area

<p>The principle of L-shaped natural ventilation system of bamboo houses, traditional buildings in the hot-humid area of Lingnan, China, is now widely applied in the design of modern high-rise buildings. Taking the typical building case, the office building of Guangzhou Zhujiang Power Plant as an example, this article studies the natural ventilation system by the experimental method of combining actual measurement and simulation. It is concluded that the application benefits of the natural ventilation system in high-rise buildings can be improved by forming a complete ventilation path, increasing the area of air inlet and the distance between air inlet and air outlet.</p><p> </p>

scholarly journals RESEARCH OF APARTMENTS’ AIR REGIME IN THE PROCESS OF OPERATION AND RECONSTRUCTION

2019 ◽  
Vol 4 (10) ◽  
pp. 53-59
Author(s):  
О. Тирон ◽  
O. Tiron ◽  
Е. Попов ◽  
E. Popov
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Operating Mode ◽  
Cold Season ◽  
Air Permeability ◽  
Normal Operation ◽  
Scale Experiment ◽  
Comparison Of The Results ◽  
Air Exchange

Insufficient air exchange of apartments in gasified apartment residential buildings, as well as an apartment’s air balance when using mechanical ventilation can cause the formation and accumulation of carbon monoxide. This work is aimed at studying the air exchange of apartments when installing kitchen hoods in apartment buildings, as well as insufficient air permeability of windows in PVC (Polyvinyl chloride) bindings during the cold season. Analytical calculations and a full-scale experiment are carried out in two apartments with and without kitchen hood. The calculated air exchanges, actual air exchanges are determined: in normal operation by tenants and in conditionally maximum operating mode with open windows. The comparison of the results of analytical calculations with experimental data shows insufficient air permeability of PVC windows to maintain the necessary air exchange of natural ventilation. It becomes obvious that there are two ways to increase air exchange: regulated - opening vents and non-normative - installation of mechanical hoods. At the same time, the use of mechanical hoods can disrupt the operation of the natural ventilation system.

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.

scholarly journals In vitro growth of Cattleya nobilior Rchb. f.: culture media, sealing systems and irradiance

2021 ◽  
Vol 51 ◽  
Author(s):  
Kaliana Gottschalk de Freitas ◽  
José Carlos Sorgato ◽  
Jackeline Schultz Soares ◽  
Luan Marlon Ribeiro
Keyword(s):  
Plant Height ◽  
Natural Ventilation ◽  
Culture Medium ◽  
Culture Media ◽  
Ventilation System ◽  
Light Condition ◽  
Leaf Length ◽  
In Vitro Growth ◽  
Randomized Design

ABSTRACT Some factors may influence the in vitro culture of native orchids, especially the culture medium, sealing system and light condition. This study aimed to evaluate the addition of banana pulp and peel in the formulation of culture media, sealing system and irradiance, in the in vitro growth of Cattleya nobilior Rchb. f. A completely randomized design was used in a factorial scheme with five culture media [Murashige & Skoog supplemented or not with banana pulp or peel (100 or 200g L-1)], two light conditions [3,000 K LED lamps (43 µmol m-2 s-1 or 86 µmol m-2 s-1)] and two sealing systems (natural and conventional ventilation), with six replicates of one vial each. The plant height, diameter of the largest pseudobulb, length of the largest root and of the largest leaf, fresh weight and number of leaves, roots and shoots were evaluated. The use of both the banana pulp and peel as additives in the culture medium formulation promoted the C. nobilior growth. The natural ventilation system increased the plant height, pseudobulb diameter and leaf length, while the conventional system promoted tillering.

Noise reduction of enhanced acoustic balconies on a high-rise building block

2021 ◽  
Vol 263 (1) ◽  
pp. 5327-5334
Author(s):  
SK Tang ◽  
Rudolf YC Lee
Keyword(s):  
Noise Reduction ◽  
Natural Ventilation ◽  
Traffic Noise ◽  
Elevation Angle ◽  
Noise Levels ◽  
Indoor Space ◽  
New Device ◽  
Air Inlet ◽  
The Difference ◽  
The Impact

A new device called 'enhanced acoustic balcony' is installed in a new housing estate in Hong Kong. It is intended to help reduce the impact of traffic noise on the residents. This balcony is basically an enlarged form of a plenum window and with three openings. Apart from the outdoor air inlet, there is the balcony door and a side-hung window on the interior balcony wall for natural ventilation of the indoor space. Sound absorption of NRC 0.7 is installed on the balcony ceiling and its sidewall facing the incoming traffic noise and an inclined panel is installed outside the balcony to provide noise screening. A site measurement of its noise reduction is carried out in the present study in a newly completed housing block. A 28 m long loudspeaker array is used as the sound source. The indoor noise levels are measured according to ISO standard. The results show that the difference between indoor and outdoor noise levels in the presence of this balcony form varies over a relatively narrow range between 10 to 13 dBA for an elevation angle from 25 to 60 deg. There is a weak increase of the noise level difference with elevation angle.

An Attempt to Improve Air Quality in Primary Schools

2017 ◽  
Author(s):  
Marek Telejko ◽  
Ewa Zender-Swiercz
Keyword(s):  
Air Quality ◽  
Primary School ◽  
Indoor Air ◽  
Primary Schools ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Co2 Concentration ◽  
School Buildings ◽  
Maximum Value

Most primary school buildings in Poland rely on natural ventilation. This fact is attributed to the age of these buildings constructed more than dozen or even several tens of years ago. Few of them were fitted with a mechanical ventilation system allowing for the adjustment of microclimate parameters. The national requirements for gravity ventilation provide general guidelines, specifying strict description only for the airtightness of windows and doors and the minimum airflow to be supplied to the rooms. The minimum airflow supplied is independent of the number of occupants and purpose of the room. Low indoor air quality (IAQ) can impact occupants’ health and lead to poor productivity or low academic performance. Therefore the provision of good IAQ in classrooms and laboratories is very important. This paper presents the results of the investigation devoted to the quality of indoor air in classrooms of selected Polish primary school. Six primary school in a town with a population of 200 000 inhabitants were involved in the investigations. The participating school buildings were built between 1976 and 1994 and had gravity ventilation systems. The variability of basic IAQ parameters, i.e., temperature, relative humidity and carbon dioxide level, was analysed and the assessment of the classrooms in terms of microbiological purity was performed. The outcomes confirmed the low quality of the indoor air in these buildings. The maximum value of CO2 concentration amounted to more than 4000 ppm. Certain modifications aimed at improving IAQ were proposed during the investigations. Two solutions were implemented. The results of this study indicate that the proposed solution offers the potential to improve IAQ within classrooms.

Efficiency of Natural Ventilation in Central Greenhouse of Botanical Garden in Kosice

2017 ◽  
Author(s):  
Martin Kovac ◽  
Katarina Kovacova ◽  
Anna Sedlakova
Keyword(s):  
Indoor Environment ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Botanical Garden ◽  
Simulation Tool ◽  
Summer Period ◽  
Radiation Level ◽  
Glass Panels ◽  
The Right ◽  
Calculated Model

The object of paper is analysis of natural ventilation system in central greenhouse of Botanical garden in Kosice. The greenhouse was refurbished in 2015. The existing greenhouse covering from glass panels was replaced for polycarbonate panels. The ventilation system of central greenhouse is natural and there are used openings in covering (wall, roof). It is combination of thermally and wind driven ventilation. The main aim of contribution is to analyse different modes of natural ventilation during summer period mainly. The important factors that influence efficiency of natural ventilation in greenhouse are location and area of openings, temperature stratification in greenhouse, solar radiation level, wind speed and direction too. If the greenhouse is ventilated naturally only through external windows (roof windows are closed) the efficiency of ventilation is very poor. The defined modes of natural ventilation search the right location and size of opened windows in order to achieve the most efficiency ventilation of indoor environment. For this purpose the progressive dynamic simulation tool DesignBuilder is used where the geometrical and specific calculated model of whole central greenhouse was created.

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