A Tracer Gas Decay System for Monitoring Air Infiltration and Air Movement in Large Single Cell Buildings

2008 ◽  
pp. 266-266-21 ◽  
Author(s):  
R WatersJohn ◽  
GV Lawrance ◽  
N Jones
Keyword(s):  
Single Cell ◽  
Tracer Gas ◽  
Air Infiltration ◽  
Air Movement

Computational fluid dynamics evaluation of the furniture arrangement for ventilation efficiency

2018 ◽  
Vol 39 (5) ◽  
pp. 557-571 ◽  
Author(s):  
Susana Hormigos-Jimenez ◽  
Miguel Ángel Padilla-Marcos ◽  
Alberto Meiss ◽  
Roberto Alonso Gonzalez-Lezcano ◽  
Jesús Feijó-Muñoz
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Efficiency ◽  
Indoor Air ◽  
Tracer Gas ◽  
Steady State Method ◽  
Air Movement ◽  
Ventilation Efficiency ◽  
State Method ◽  
Furniture Arrangement

People spend most of their time indoors; therefore, maintaining a good indoor air quality and meeting the requirements of comfort and energy efficiency are essential. One of the most widespread strategies to achieve this objective is improving ventilation efficiency; therefore, the main aim of this study was to show an optimization of the ventilation efficiency, in a specific room, considering 47 variations (case studies) in the furniture arrangement. For this purpose, a numerical analysis using computational fluid dynamics techniques, validated by the tracer gas decay technique, was used to assess the distribution of the age of air within the space. The concept of “age of air” was implemented in the computational fluid dynamics code through user-defined functions, using the steady-state method based on the resolution of a transport equation for an additional scalar. Variations up to 5.75% in the ventilation efficiency between the cases studied have been achieved. It is concluded that an improvement up to 1.65% can be obtained when the elements of the study are introduced in a way that facilitates the air movement towards the exhaust; therefore, improvement of the ventilation efficiency through specific furniture distributions is possible, although not significant, according to the outcomes.

scholarly journals Evaluating methods for estimating whole house air infiltration rates in summer: implications for overheating and indoor air quality

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ben M. Roberts ◽  
David Allinson ◽  
Kevin J. Lomas
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Infiltration Rate ◽  
Estimation Methods ◽  
Tracer Gas ◽  
Content Type ◽  
Infiltration Rates ◽  
Air Infiltration ◽  
Fan Pressurisation

PurposeAccurate values for infiltration rate are important to reliably estimate heat losses from buildings. Infiltration rate is rarely measured directly, and instead is usually estimated using algorithms or data from fan pressurisation tests. However, there is growing evidence that the commonly used methods for estimating infiltration rate are inaccurate in UK dwellings. Furthermore, most prior research was conducted during the winter season or relies on single measurements in each dwelling. Infiltration rates also affect the likelihood and severity of summertime overheating. The purpose of this work is to measure infiltration rates in summer, to compare this to different infiltration estimation methods, and to quantify the differences.Design/methodology/approachFifteen whole house tracer gas tests were undertaken in the same test house during spring and summer to measure the whole building infiltration rate. Eleven infiltration estimation methods were used to predict infiltration rate, and these were compared to the measured values. Most, but not all, infiltration estimation methods relied on data from fan pressurisation (blower door) tests. A further four tracer gas tests were also done with trickle vents open to allow for comment on indoor air quality, but not compared to infiltration estimation methods.FindingsThe eleven estimation methods predicted infiltration rates between 64 and 208% higher than measured. The ASHRAE Enhanced derived infiltration rate (0.41 ach) was closest to the measured value of 0.25 ach, but still significantly different. The infiltration rate predicted by the “divide-by-20” rule of thumb, which is commonly used in the UK, was second furthest from the measured value at 0.73 ach. Indoor air quality is likely to be unsatisfactory in summer when windows are closed, even if trickle vents are open.Practical implicationsThe findings have implications for those using dynamic thermal modelling to predict summertime overheating who, in the absence of a directly measured value for infiltration rate (i.e. by tracer gas), currently commonly use infiltration estimation methods such as the “divide-by-20” rule. Therefore, infiltration may be overestimated resulting in overheating risk and indoor air quality being incorrectly predicted.Originality/valueDirect measurement of air infiltration rate is rare, especially multiple tests in a single home. Past measurements have invariably focused on the winter heating season. This work is original in that the tracer gas technique used to measure infiltration rate many times in a single dwelling during the summer. This work is also original in that it quantifies both the infiltration rate and its variability, and compares these to values produced by eleven infiltration estimation methods.

Comparison of Blower Door and Tracer Gas Testing Methods for Determination of Air Infiltration Rates Through Building Envelopes at Normal Operating Conditions

2011 ◽  
Author(s):  
Tapan Patel ◽  
Constandinos Mitsingas ◽  
James P. Miller ◽  
Ty A. Newell
Keyword(s):  
Building Envelope ◽  
Leakage Rate ◽  
Operating Conditions ◽  
Air Leakage ◽  
Tracer Gas ◽  
Annual Average ◽  
Normal Operating ◽  
Infiltration Rates ◽  
Air Infiltration ◽  
Air Leakage Rate

Tracer gas and blower door testing are two widely used methods to determine the rate of air infiltration through a building envelope. Blower door testing is performed at elevated pressure differentials across the building envelope whereas tracer gas testing is conducted at near zero differential pressures, better reflecting the air leakage rate at near normal building operating conditions. The primary objective of this study was to determine whether extrapolation of blower door test data to normal building operating conditions provides a good estimate of annual average air infiltration at those conditions. Two methods were used to extrapolate the data and were then compared to the baseline tracer gas tests. A secondary objective was to determine the ventilation rate of a residential facility using tracer gas tests. Tracer gas testing seems to be more reliable in determining the air leakage rate at normal operating pressures, but is sensitive to the tracer gas and ambient weather conditions. Regardless, for the subject facility, the ACH50/20 rule and Sherman’s ACH50/N correlation, extrapolated from the blower door tests, are within 6%–33% and 4%–38% of the tracer gas results, respectively. However, these errors are dependent on the assumptions used. Nevertheless, it appears that simple blower door testing can provide a reasonable measure of a building’s annual average air infiltration rate regardless of ambient conditions, whereas the more expensive and complex tracer gas tests may better reflect seasonal variations in air infiltration rates.

Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

1992 ◽  
Vol 50 (2) ◽  
pp. 1104-1105
Author(s):  
Debby A. Jennings ◽  
Michael J. Morykwas ◽  
Louis C. Argenta
Keyword(s):  
Electron Microscopy ◽  
Cell Suspension ◽  
Single Cell ◽  
Chronic Wounds ◽  
Mechanical Stability ◽  
Uv Light ◽  
Type I ◽  
Single Cell Suspension ◽  
Collagen Substrate ◽  
Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

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