scholarly journals Spatial distributions of airborne dust in a cows barn exposed to influence of different ventilation rates

2013 ◽  
Vol 29 (2) ◽  
pp. 373-383
Author(s):  
G. Topisirovic ◽  
D.V. Petrovic ◽  
R. Maletic
Keyword(s):  
Flow Rate ◽  
Indoor Air ◽  
Rotation Rate ◽  
Natural Ventilation ◽  
Electronic Control Unit ◽  
Air Flow ◽  
Control Unit ◽  
Dust Particles ◽  
Airborne Dust ◽  
Stability And Instability

Information on the concentration of dust particles is an important microclimate parameter that characterizes the local environmental quality of each livestock building. Increased concentration of dust particles primarily affects the indoor air quality and, consequently, the animal and workers health. Among many others, ventilation rate is a vital parameter that controls the spatial distribution of airborne dust particles in livestock buildings. This was the main motive for authors of this paper to research the influence of rotation rate of under-roof axial fans (i.e. the air flow rate) on airborne dust particles distribution crossover the barn specified for tied cows breeding. During a series of performed experiments, six different air flow rates have been maintained in the range between 0 m3?h-1 and 48000 m3?h-1. Flow rate has been controlled by special electronic control unit, which provided six different rotation rates of two under-roof fans, including the neutral regime (natural ventilation only). Measurements have been performed at four typical height levels (0,5 m; 1,0 m; 1,5 m and 2,0 m), cross-over the three lateral and four longitudinal characteristic building sections. Consequently, 48 measuring points were appropriately selected, in order to cover the indoor space in adequate way. Comparative analysis of air flow velocities and dust concentrations showed that this fan setup may give satisfactory results under adequate operational regime. Certain working regimes were recommended for use, and the third rotation rate step, generating the airflow of 37300 m3?h-1 or indoor air exchange level of approximately 25 h-1, has been found as the most suitable. Projekat Ministarstva nauke Republike Srbije, br. TR31086: Optimization of technological procedures and zoo-technical resources on farmsin purpose of milk production sustainability improvement, br. TR 31051: Improvement of biotechnological procedures as a function of rational utilizationof energy, agricultural products productivity and quality increase, br. III46009: Improvement and development new technological procedures in production ofanimal products, to achieve high quality and safe competitive products inmarket i br. OI 174011: Dynamical stability and instability of mechanical systems exposed to stochasticdisturbances

scholarly journals Indoor Air Quality (IAQ): Accuracy of Natural Ventilation for Temperature, Air Flow Rate and Relative Humidity (RH) in School Building Classrooms

2018 ◽  
Vol 7 (3.9) ◽  
pp. 42
Author(s):  
Norsafiah Norazman ◽  
Adi Irfan Che Ani ◽  
Nor Haslina Ja’afar ◽  
Muhamad Azry Khoiry
Keyword(s):  
Air Quality ◽  
Relative Humidity ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Air Flow ◽  
Weather Conditions ◽  
Potential Health ◽  
The Hours ◽  
Hot Weather

Indoor Air Quality (IAQ) is an essential matter in achieving students’ satisfaction for the learning process. Building’s orientation is a factor that may encourage sufficient natural ventilation for the classroom occupants. Inadequate ventilation is an issue for most existing classrooms. The purpose of this paper is to analyze the accuracy of natural ventilation in classrooms. Therefore, experimental on 20 classrooms has been conducted by using Multipurpose Meter at secondary school buildings in Malaysia. The findings indicated that the accuracy of natural ventilation testing was below the permissible limits throughout the hours monitored, thus this may cause potential health hazards to the students. Temperature and air flow rates were lower than 23 °C and 0.15 m/s respectively, it fulfilled the basic requirements as a standard learning environment. However, measurements taken showed the overall relative humidity (RH) in the classrooms can be categorized as acceptable with 40% to 70% range. On the basis of these findings, it is evident that naturally ventilated classrooms are important especially due to energy efficiency, whereas mechanical ventilation should only be installed as an alternative under extremely hot weather conditions.   

Large Eddy Simulation of Single-Sided Ventilated Room With Different Location of Windows

2014 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh
Keyword(s):  
Large Eddy Simulation ◽  
Flow Pattern ◽  
Flow Rate ◽  
Natural Ventilation ◽  
Air Flow ◽  
Navier Stokes ◽  
Eddy Motion ◽  
Eddy Simulation ◽  
Continuity Equations ◽  
Large Eddy

The natural ventilation contributes the improvement of internal thermal comfort and internal air quality when applied properly. An investigation of single-sided double opening was performed to a 3-dimensional rectangular-box room using a commercial Computational Fluid Dynamics (CFD) software package of ESI group. Sixteen models with different location of double-openings were investigated. The large eddy simulation (LES) turbulence model was used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion was obtained by filtering the Navier-Stokes and continuity equations. From the overall results, the lowest and the highest air flow rates were obtained to be 1.14 × 10−3 m3/s and 2.12 × 100 m3/s respectively. The location & arrangement of opening influences the air flow rate and air flow pattern.

scholarly journals Natural ventilation for office building retrofit in dense urban context under hot and humid climate

2021 ◽  
Vol 21 (2) ◽  
pp. 67-87
Author(s):  
Marilia Ramalho Fontenelle ◽  
Leopoldo Eurico Gonçalves Bastos ◽  
Sylvie Lorente
Keyword(s):  
Thermal Comfort ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Air Flow ◽  
Office Building ◽  
Temperate Climate ◽  
Humid Climate ◽  
Adaptive Comfort ◽  
Hot And Humid Climate ◽  
Indoor Air Flow

Abstract Recent studies underline that simple and non-invasive retrofit solutions can recover natural ventilation potential in existing buildings under temperate climate. Nonetheless, the efficiency of these solutions in dense urban contexts under hot and humid climate remains unclear. This paper aims to evaluate the thermal comfort gains caused by natural ventilation when retrofitting an office building in downtown Rio de Janeiro. Computational Fluid Dynamics (CFD) and thermal simulations are carried out on Ansys CFX and Design builder to assess indoor air flow before and after retrofit. The diagnosis of the current scenario indicates that the surrounding buildings block a significant part of the wind flow, and occupants experience only a few hours of thermal comfort during the year, especially on lower floors. To increase indoor air flow, the fixed upper windows were transformed into pivot windows and kept open permanently. This measure increases the annual hours of thermal comfort by 0.5-35%, depending on the floor and the adaptive comfort model. These findings suggest that natural ventilation itself may not be sufficient to ensure occupants' comfort throughout the year under the investigated context.

scholarly journals Naturally ventilated industrial sheds: an investigation about the influence of wind direction in flow rate efficiency in continuous roof vents

2021 ◽  
Vol 36 (4) ◽  
Author(s):  
B. Carmagos ◽  
H. De Souza ◽  
A. Gomes ◽  
A. Ladeira ◽  
R. Dos Reis ◽  
...  
Keyword(s):  
Flow Rate ◽  
Indoor Air ◽  
Wind Direction ◽  
Natural Ventilation ◽  
Climatic Conditions ◽  
Internal Source ◽  
Internal Temperature ◽  
Healthy Environment ◽  
Belo Horizonte ◽  
Roof Vents

Natural ventilation portrays an effective technique for lowering the internal temperature, without spending electricity, and directly contributes to the renewal of indoor air by establishing a healthy environment for workers. Given this, it is usual to have air vent openings located at the top of the roof (continuous roof vents), in addition to those present on the facades of sheds. In naturally ventilated buildings, it is recommended to give due importance to the provision of these openings, since depending on the proposed arrangement, the wind may or may not help in the effectiveness of this strategy. In this work, it is evaluated via computer simulation (EnergyPlus, version 8.7.0), for the climatic conditions of the city of Belo Horizonte/Brazil, the influence of the wind direction in the flow rate of indoor air through the ridge vents, of the longitudinal and transversal type, present in industrial sheds endowed with an internal source of high-intensity heat release. The results obtained show that the flow rate has a symmetrical behavior in the openings of the longitudinal continuous roof vent, that is, when an opening is with the maximum outflow of the internal air, the opening opposite the predominant wind direction is acting as an entry point for the air external. The transverse continuous roof vents are more sensitive about the wind direction since they are positioned perpendicular to the building. The best result found is for the wind situation occurring parallel to the shed, obtaining a reduction in the internal temperature of up to 1°C, an increase in the rate of air changes per hour, in the internal environment, at 1acph, and an increase of up to 10,7% in the volume of air infiltrated into the shed.

Field Investigation of the Small House with the Ventilated Roof Tiles

2014 ◽  
Vol 931-932 ◽  
pp. 1233-1237 ◽  
Author(s):  
Onvalee Amornleetrakul ◽  
Withaya Puangsombut ◽  
Jongjit Hirunlabh
Keyword(s):  
Flow Rate ◽  
Natural Ventilation ◽  
Air Flow ◽  
Field Investigation ◽  
Air Flow Rate ◽  
Heat Gain ◽  
Average Temperature ◽  
Roof Tile ◽  
Small House ◽  
North And South

This paper investigates the thermal performances and heat gain reduction of a new roof tile design referred as Ventilated Roof Tile (VRT) compared with an ordinary corrugated concrete roof tiles (CCR). The outside dimension of each small house was 1.70 x 1.70 x 2.85 m3 (W x L x H) and inside dimension was 1.50 x 1.50 x 2.20 m3. The volume of each room was 4.95 m3. The gable roofs slope were 25o and surface area of VRT was 2.58 m2 per each side facing north and south. The VRT tile composed of upper cement plate 40 × 40 cm2 and lower cement plate 30 x 40 cm2. Between plates was 3 cm thickness air gap. The experimental results showed that the top surface of VRT was lower than CCR about 2.10°C for average temperature (from 6:00 18:00) and made VRT room temperature lower than CCR about 1.41°C for average temperature. VRT could reduce heat gain with air flow rate through the roof tiles gaps varied following the solar radiation, during time 8:00-17:00 the natural ventilation varied from 0.003-0.014 m3/s (10.6-50.0 m3/hr.). Observed that, during 17:00-18:00, the air flow rate is about 0.003 m3/s (10.8 m3/hr.) due to heat accumulated in the attic space and roof tiles.

Determining the Ventilation Rate inside an Apartment House on the Basis of Measured Carbon Dioxide Concentrations – Case Study

2017 ◽  
Author(s):  
Peter Kapalo ◽  
Silvia Vilčeková ◽  
Florin Domnita ◽  
Ciprian Bacotiu ◽  
Orest Voznyak
Keyword(s):  
Carbon Dioxide ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Flow Rate ◽  
Indoor Air ◽  
Residential Buildings ◽  
Air Flow ◽  
Air Flow Rate ◽  
Apartment House ◽  
Carbon Dioxide Concentrations

In the construction process of modern residential buildings the aim is to achieve maximum comfort within minimum energy consumption. One of the ways to achieve this requirement is the accurate determination of the volumetric air flow rate necessary to ensure the required indoor air quality. The aim of the paper is to present a methodology for determination the volumetric air flow rate on the basis of the results obtained from experimental measurements of carbon dioxide concentrations, which were carried out inside an apartment house lived by a standard family. Based on the measured values, the mass flow rate release of carbon dioxide was calculated. Consequently, the volumetric air flow rate was calculated in two situations, during the day and during the night. The main goal of the paper is to determine the required fresh air flow rate in an occupied room, based on carbon dioxide concentration measurement, in order to maintain a comfortable level of indoor air quality. The calculated air flow rate should optimize a future investment in ventilation equipment in order to choose the proper air handling unit with low operating costs. The aim is not only to improve the energy efficiency of the ventilation system, but also to ensure a healthy indoor environment. Based on the presented research it can be stated that during the sleeping of four family members there is necessary to ensure the fresh air flow rate of 104 m3 per hour.

scholarly journals Regulation of the air cushionat a sewer network of the siphon type

2021 ◽  
Vol 18 (4) ◽  
pp. 91-99
Author(s):  
S. V. Fedorov ◽  
◽  
V. M. Vasilyev ◽  
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Control Unit ◽  
Environmental Safety ◽  
Jet Stream ◽  
Air Flow Rate ◽  
Model Calculations ◽  
Sewer Network ◽  
Ansys Cfx ◽  
Air Cushion

In order to improve the energy efficiency and environmental safety of the main sewerage system, it is recommended to use the air cushion effect. This effect will allow flushing the system, removing the air to the air purification unit in an orderly manner, lifting the sewage due to the pressure in the air cushion. For provision of reliable operation of the sewer network, it is necessary to maintain the required level of wastewater in the conditions of constantly changing gas-air flow rate. The paper proposes the design of the air cushion control unit, which operates on the basis of a triangular spillway. This design allows making the system self-regulating, automatically removing excess gas-air environment. The jet stream on the spillway moves under the condition of a changing cross-section of the outlet orifice. This condition fundamentally distinguishes the outflow of the air from the existing research in the field of underwater air and gas jets. Therefore, this is the basis for conducting our own research to assess the capacity of a triangular shaped spillway. The study of the jet stream was performed using the ANSYS CFX program. Model calculations were carried out for the range of air flow rate from 0.0078 to 1 l / s. There was used the π-theorem to evaluate the operation of the spillway in a different flow range and at different values of the inclination angle of the edge α. The results of the study can be used in practice to develop a control unit and implement a sewage system operating in the air cushion mode.

scholarly journals Naturally ventilated industrial sheds: an investigation about the influence of wind direction in flow rate efficiency in continuous roof vents

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
B. Camargos ◽  
H. De Souza ◽  
A. Gomes ◽  
A. Ladeira ◽  
R. Dos Reis ◽  
...  
Keyword(s):  
Flow Rate ◽  
Indoor Air ◽  
Wind Direction ◽  
Natural Ventilation ◽  
Climatic Conditions ◽  
Internal Source ◽  
Internal Temperature ◽  
Healthy Environment ◽  
Belo Horizonte ◽  
Roof Vents

Natural ventilation portrays an effective technique for lowering the internal temperature, without spending electricity, and directly contributes to the renewal of indoor air by establishing a healthy environment for workers. Given this, it is usual to have air vent openings located at the top of the roof (continuous roof vents), in addition to those present on the facades of sheds. In naturally ventilated buildings, it is recommended to give due importance to the provision of these openings, since depending on the proposed arrangement, the wind may or may not help in the effectiveness of this strategy. In this work, it is evaluated via computer simulation (EnergyPlus, version 8.7.0), for the climatic conditions of the city of Belo Horizonte/Brazil, the influence of the wind direction in the flow rate of indoor air through the ridge vents, of the longitudinal and transversal type, present in industrial sheds endowed with an internal source of high-intensity heat release. The results obtained show that the flow rate has a symmetrical behavior in the openings of the longitudinal continuous roof vent, that is, when an opening is with the maximum outflow of the internal air, the opening opposite the predominant wind direction is acting as an entry point for the air external. The transverse continuous roof vents are more sensitive about the wind direction since they are positioned perpendicular to the building. The best result found is for the wind situation occurring parallel to the shed, obtaining a reduction in the internal temperature of up to 1°C, an increase in the rate of air changes per hour, in the internal environment, at 1acph, and an increase of up to 10,7% in the volume of air infiltrated into the shed.

scholarly journals Air preheating potential with high Opaque Ventilated Façade under natural and forced convection

2021 ◽  
Vol 2069 (1) ◽  
pp. 012023
Author(s):  
T Colinart ◽  
H Noel ◽  
M Batard ◽  
A Fuentes ◽  
A Magueresse ◽  
...  
Keyword(s):  
Forced Convection ◽  
Flow Rate ◽  
Natural Ventilation ◽  
Positive Impact ◽  
Air Flow ◽  
Thermal Flux ◽  
Building Envelope ◽  
Design Parameters ◽  
Building Energy Efficiency ◽  
Air Flow Rate

Abstract Opaque ventilated façades (OVF) are increasingly used in building envelope because of their positive impact on building energy efficiency. Usually, air flow is driven by natural ventilation. Recently, there were some attempts to drive air flow mechanically to preheat or precool air in combination with HVAC, Heat pump or Latent Heat Thermal Energy Storage (LHTES) systems. In this framework, an experimental real-scale module of an OVF was built (1.9 m width and 3.5 m height). In this study, OVF is tested during autumn under natural and under forced convection by means of ventilator placed at cavity outlet. Inlet air flowrate are changed from day to day or during the day. For each test, temperature, air velocity, air flow rate and thermal flux are monitored at different locations of OVF. Their analysis shows that collector efficiency and amount of collected energy depend mainly on cavity air flow rate. The measurements are compared to simulation results obtained from two thermal models describing OVF: Trnsys Type 1230 and home-developed pseudo 2D. A good agreement is found for air temperature at cavity outlet while differences are observed in opaque layers due to modelling assumptions. Last, sensitivity analysis on two design parameters is carried out.

Sign in / Sign up

Export Citation Format

Share Document