Air renewal times and ventilation rate calculations for underground workings using radioactive measurement

Double skin ventilated roof is one of the important passive cooling techniques to reduce solar heat gain through roofs. In this research, an experimental study was performed to investigate the thermal behaviour of a double skin roof model. The model was made of two parallel galvanized steel plates. Galvanized steel has been used in the roof construction of industrial buildings and storehouses in Iraq. The effect of inclination angle (ϴ) from the horizontal and the spacing (S) between the plates was investigated at different radiation intensities. It is found that using a double skin roof arrangement with a sufficient air gap (S) can reduce the heat gain significantly. The higher the inclination angle (ϴ) the higher the ventilation rate, the lower the heat gain through the roof. In this study, increasing the air gap from 2 cm to 4 cm reduced the heat gain significantly but when the gap was further increased to 6 cm, the reduction in the heat flux was insignificant. A dimensionless correlation was also reduced between Nusselt number () and the single parameter where L is the channel length. This correlation can be handily utilized for designing of engineering applications dealing with high temperature difference natural convection heat transfer.

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Ventilation Rate and End -- Tidal Steady State Pulmonary Diffusing Capacity (DLCOss2) at Rest

Scandinavian Journal of Clinical and Laboratory Investigation ◽

10.3109/00365517409082509 ◽

1974 ◽

Vol 33 (4) ◽

pp. 379-386

Author(s):

G. Sundström

Keyword(s):

Steady State ◽

Ventilation Rate ◽

Diffusing Capacity ◽

Pulmonary Diffusing Capacity ◽

End Tidal

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Estimation of the Inhaled Dose of Pollutants in Different Micro-Environments: A Systematic Review of the Literature

Toxics ◽

10.3390/toxics9060140 ◽

2021 ◽

Vol 9 (6) ◽

pp. 140

Author(s):

Francesca Borghi ◽

Andrea Spinazzè ◽

Simone Mandaglio ◽

Giacomo Fanti ◽

Davide Campagnolo ◽

...

Keyword(s):

Systematic Review ◽

Residence Time ◽

Low Cost ◽

Pulmonary Ventilation ◽

Personal Exposure ◽

Ventilation Rate ◽

Atmospheric Pollutants ◽

Active Commuting ◽

Review Of The Literature ◽

Future Studies

Recently, the need to assess personal exposure in different micro-environments has been highlighted. Further, estimating the inhaled dose of pollutants is considerably one of the most interesting parameters to be explored to complete the fundamental information obtained through exposure assessment, especially if associated with a dose-response approach. To analyze the main results obtained from the studies related to the estimation of the inhaled dose of pollutants in different micro-environments (environments in which an individual spends a part of his day), and to identify the influence of different parameters on it, a systematic review of the literature was performed. The principal outcomes from the considered studies outlined that (i) exposure concentration and residence time are among the most important parameters to be evaluated in the estimation of the inhaled dose, especially in transport environments. Further, (ii) the pulmonary ventilation rate can be of particular interest during active commuting because of its increase, which increases the inhalation of pollutants. From a methodological point of view, the advent of increasingly miniaturized, portable and low-cost technologies could favor these kinds of studies, both for the measurement of atmospheric pollutants and the real-time evaluation of physiological parameters used for estimation of the inhaled dose. The main results of this review also show some knowledge gaps. In particular, numerous studies have been conducted for the evaluation (in terms of personal exposure and estimation of the inhaled dose) of different PM fractions: other airborne pollutants, although harmful to human health, are less represented in studies of this type: for this reason, future studies should be conducted, also considering other air pollutants, not neglecting the assessment of exposure to PM. Moreover, many studies have been conducted indoors, where the population spends most of their daily time. However, it has been highlighted how particular environments, even if characterized by a shorter residence time, can contribute significantly to the dose of inhaled pollutants. These environments are, therefore, of particular importance and should be better evaluated in future studies, as well as occupational environments, where the work results in a high pulmonary ventilation rate. The attention of future studies should also be focused on these categories of subjects and occupational studies.

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Odour, dust and non-methane volatile organic-compound emissions from tunnel-ventilated layer-chicken sheds: a case study of two farms

Animal Production Science ◽

10.1071/an12343 ◽

2013 ◽

Vol 53 (12) ◽

pp. 1309 ◽

Cited By ~ 3

Author(s):

Mark Dunlop ◽

Zoran D. Ristovski ◽

Erin Gallagher ◽

Gavin Parcsi ◽

Robin L. Modini ◽

...

Keyword(s):

Dust Emission ◽

Ventilation Rate ◽

Gas Chromatography Mass Spectrometry ◽

Emission Rates ◽

Layer Chicken ◽

Volatile Organic ◽

Different Seasons ◽

Odour Emissions ◽

Cleaning Cycle ◽

Study Sites

An observational study was undertaken to measure odour and dust (PM10 and PM2.5) emission rates and identify non-methane volatile organic compounds (NMVOCs) and odorants in the exhaust air from two tunnel-ventilated layer-chicken sheds that were configured with multi-tiered cages and manure belts. The study sites were located in south-eastern Queensland and the West Gippsland region of Victoria, Australia. Samples were collected in summer and winter on sequential days across the manure-belt cleaning cycle. Odour emissions ranged from 58 to 512 ou/s per 1000 birds (0.03–0.27 ou/s.kg) and dust emission rates ranged 0.014–0.184 mg/s per 1000 birds for PM10 and 0.001–0.190 mg/s per 1000 birds for PM2.5. Twenty NMVOCs were identified, including three that were also identified as odorants using thermal desorption–gas chromatography–mass spectrometry/olfactometry analysis. Odour emission rates were observed to vary with the amount of manure accumulation on the manure belts, being lowest 2–4 days after removing manure. Odour emission rates were also observed to vary with diurnal and seasonal changes in ventilation rate. Dust emissions were observed to increase with ventilation rate but not with manure accumulation. Some NMVOCs were identified at both farms and in different seasons whereas others were observed only at one farm or in one season, indicating that odorant composition was influenced by farm-specific practices and season.

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Enhancing Air Quality for Embedded Hospital Germicidal Lamps

Sustainability ◽

10.3390/su13042389 ◽

2021 ◽

Vol 13 (4) ◽

pp. 2389

Author(s):

Jung-Shun Chen

Keyword(s):

Air Quality ◽

Hospital Staff ◽

Ventilation Rate ◽

Hospital Environment ◽

Design Stage ◽

Flow Noise ◽

Air Ventilation ◽

Air Disinfection ◽

Type 3

The indoor air of a hospital is always full of bacteria and viruses due to patients with different diseases. These bacteria and viruses could be highly infectious to the people in the hospital irrespective of their health conditions, and could be hazardous to the patients, their care takers, and hospital staff. Thus, keeping a good hospital air quality is very essential to the operation of the hospital. This study aims at enhancing ventilation of the interior lighting of hospitals with germicidal capabilities. Air disinfection is accomplished by adding the specially designed disinfecting filters and fans to existing embedded lamps in the hospitals. The embedded lamp has a square shape of 601 mm in width and 112 mm in thickness. In the design stage, the air flow inside the embedded lamp with the added filters and fans was investigated by numerical simulation using a computational fluid dynamics (CFD) tool. Three designs, referred to as Types 1, 2, and 3, were evaluated using steady-state CFD flow simulations. The ventilation rate of the Type 1 design was about 251.9 CMH, and 348.3 CMH for the Type 2 design by increasing the fan outlet area. However, even though the ventilation was increased by 34%, the flow field of the Type 2 design was not uniform, resulting in flows being circulated around the side locations. Thus, the Type 3 design further treats this aspect by streamlining the outlet geometry and adding flow guiding vanes to reduce flow resistance and flow unsteadiness; the corresponding air ventilation rate reached 376.3 CMH. Hence, the Type 3 design was fabricated and tested. The test results confirm that the design not only has a higher ventilation rate but also operates under a smaller pressure drop, thus accomplishing the goal of providing good air quality in the hospital environment efficiently. Moreover, the associated flow noise is reduced by about 8 dBA. Hence, both an increase in the air ventilation rate and a reduction of noise are achieved simultaneously by the present method.

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Numerical Simulation of the Mechanical Behavior of Fiber-Reinforced Cement Composites Subjected Dynamic Loading

Applied Sciences ◽

10.3390/app11031112 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1112

Author(s):

Nikita Belyakov ◽

Olga Smirnova ◽

Aleksandr Alekseev ◽

Hongbo Tan

Keyword(s):

Numerical Simulation ◽

Reinforced Concrete ◽

Dynamic Loading ◽

Fiber Reinforced Concrete ◽

Cement Composites ◽

Fiber Reinforced ◽

Lab Experiments ◽

Reinforced Cement ◽

Underground Workings ◽

Concrete Damaged Plasticity

The problem of damage accumulation in fiber-reinforced concrete to structures supporting underground workings and tunnel linings against dynamic loading is insufficiently studied. The mechanical properties were determined and the mechanism of destruction of fiber-reinforced concrete with different reinforcement parameters is described. The parameters of the Concrete Damaged Plasticity model for fiber-reinforced concrete at different reinforcement properties are based on the results of lab experiments. Numerical simulation of the composite concrete was performed in the Simulia Abaqus software package (Dassault Systemes, Vélizy-Villacoublay, France). Modeling of tunnel lining based on fiber-reinforced concrete was performed under seismic loading.

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Simultaneous Monitoring of Particle-Bound PAHs Inside a Low-Energy School Building and Outdoors over Two Weeks in France

Atmosphere ◽

10.3390/atmos12010108 ◽

2021 ◽

Vol 12 (1) ◽

pp. 108

Author(s):

Céline Liaud ◽

Sarah Chouvenc ◽

Stéphane Le Calvé

Keyword(s):

Particle Size ◽

Air Quality ◽

High Performance ◽

Sampling Period ◽

Temporal Variations ◽

Ventilation Rate ◽

Low Energy ◽

Total Particle ◽

Polycyclic Aromatic ◽

Individual Pahs

The emergence of new super-insulated buildings to reduce energy consumption can lead to a degradation of the indoor air quality. While some studies were carried out to assess the air quality in these super-insulated buildings, they were usually focused on the measurement of gas phase pollutants such as carbon dioxide and volatile organic compounds. This work reports the first measurements of Polycyclic Aromatic Hydrocarbons (PAHs) associated with particles as a function of time and particle size in a low-energy building. The airborne particles were collected indoors and outdoors over three to four days of sampling using two three-stage cascade impactors allowing to sample simultaneously particles with aerodynamic diameter Dae > 10 µm, 2.5 µm < Dae < 10 µm, 1 µm < Dae < 2.5 µm, and Dae < 1 µm. The 16 US-EPA priority PAHs were then extracted and quantified by high-performance liquid chromatography (HPLC) coupled to fluorescence detection. The resulting total particle concentrations were low, in the ranges 3.73 to 9.66 and 0.60 to 8.83 µg m-3 for indoors and outdoors, respectively. Thirteen PAHs were always detected in all the samples. The total PAH concentrations varied between 290 and 415 pg m−3 depending on the particle size, the environment (indoors or outdoors) and the sampling period considered. More interestingly, the temporal variations of individual PAHs highlighted that high molecular weight PAHs were mainly associated to the finest particles and some of them exhibited similar temporal behaviors, suggesting a common emission source. The indoor-to-outdoor concentration ratios of individual PAH were usually found close to or less than 1, except during the event combining rainy conditions and limited indoor ventilation rate.

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Proposing Alternative Solutions to Enhance Natural Ventilation Rates in Residential Buildings in the Cfa Climate Zone of Rasht

Sustainability ◽

10.3390/su13020679 ◽

2021 ◽

Vol 13 (2) ◽

pp. 679

Author(s):

Roya Aeinehvand ◽

Amiraslan Darvish ◽

Abdollah Baghaei Daemei ◽

Shima Barati ◽

Asma Jamali ◽

...

Keyword(s):

Natural Ventilation ◽

Residential Buildings ◽

Residential Building ◽

Ventilation Rate ◽

Humid Climate ◽

The Sustainable Development ◽

Passive Strategies ◽

Development Goals ◽

Ventilation Rates ◽

Ventilation Systems

Today, renewable resources and the crucial role of passive strategies in energy efficiency in the building sector toward the sustainable development goals are more indispensable than ever. Natural ventilation has traditionally been considered as one of the most fundamental techniques to decrease energy usage by building dwellers and designers. The main purpose of the present study is to enhance the natural ventilation rates in an existing six-story residential building situated in the humid climate of Rasht during the summertime. On this basis, two types of ventilation systems, the Double-Skin Facade Twin Face System (DSF-TFS) and Single-Sided Wind Tower (SSWT), were simulated through DesignBuilder version 4.5. Then, two types of additional ventilation systems were proposed in order to accelerate the airflow, including four-sided as well as multi-opening wind towers. The wind foldable directions were at about 45 degrees (northwest to southeast). The simulation results show that SSWT could have a better performance than the aforementioned systems by about 38%. Therefore, the multi-opening system was able to enhance the ventilation rate by approximately 10% during the summertime.

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