Experimental Investigation of Ventilation Effectiveness in an Airliner Cabin Mockup

2016 ◽  
Author(s):  
Jignesh A. Patel ◽  
Byron W. Jones ◽  
Mohammad H. Hosni ◽  
Ali Keshavarz
Keyword(s):  
Distribution System ◽  
Ventilation Rate ◽  
Mean Value ◽  
Tracer Gas ◽  
Flight Duration ◽  
Factors Affecting ◽  
Aircraft Cabin ◽  
Local Ventilation ◽  
Effective Ventilation ◽  
Ventilation Effectiveness

Frequent air travel and long flight duration makes the study of airliner cabin environmental quality a topic of utmost importance. Ventilation effectiveness is one of the more crucial factors affecting air quality in any environment. Ventilation effectiveness, along with the overall ventilation rate, is a measure of the ability of the air distribution system to remove internally generated pollutants or contaminants from a given space. Because of the high occupant density in an aircraft cabin, local variations in ventilation are important as a passenger will occupy the same space for the duration of the flight. Poor ventilation in even a small portion of the cabin could impact multiple people for extended time periods. In this study, the local effective ventilation rates and local ventilation effectiveness in an eleven-row, full-scale, Boeing 767 cabin mockup were measured. These measurements were completed at each of the 77 seats in the mockup. Each seat was occupied by a heated mannequin. In order to simulate the thermal load inside the cabin, the mannequins were wrapped with a heating wire to generate approximately 100 W (341 BTU/hour) of heat. Carbon dioxide was used as a tracer gas for the experiments and the tracer gas decay method was employed to calculate the local effective ventilation rate and local ventilation effectiveness. The overall ventilation rate, based on total supply air flow, was approximately 27 air changes per hour. Local ventilation effectiveness ranged from 0.86 to 1.02 with a mean value of 0.94. These ventilation effectiveness values are higher than typically found in other indoor applications and are likely due to the relatively high airspeeds present in the aircraft cabin and the high degree of mixing they provide. The uniformity is also good with no areas of particularly low ventilation effectiveness being identified. No clear patterns with respect to seat location, window versus center versus aisle, were found.

Improving local ventilation prediction by accounting for inter-segmental ventilation

2016 ◽  
Vol 87 (5) ◽  
pp. 511-527 ◽  
Author(s):  
Nagham Ismail ◽  
Nesreen Ghaddar ◽  
Kamel Ghali
Keyword(s):  
Wind Velocity ◽  
Ventilation Rate ◽  
Air Permeability ◽  
Statistical Correlation ◽  
Accurate Estimation ◽  
Thermal Manikin ◽  
Tracer Gas ◽  
Local Ventilation ◽  
Wind Velocities ◽  
Ventilation Rates

The inter-segmental ventilation rate at clothing inter-connection of arms and trunk affects the estimation of local ventilation rates of these clothed segments. The accurate estimation of the inter-segmental ventilation rate is based on the integration of a connected clothed cylinders model with a bio-heat model to predict a realistic segmental skin temperature. This integration is validated with experiments on a thermal manikin using the tracer gas method. The results show that accounting for the inter-segmental ventilation rate improves the estimation of the segmental ventilation of the arm and the trunk for different garment apertures at external wind velocities less than 4 m/s. For a wind velocity of 1 m/s, the inter-connection increased the trunk ventilation by up to 12% and heat loss by up to 5.46%. A statistical correlation is established for the inter-segmental ventilation rate in terms of the influencing parameters: air permeability, wind velocity, mean air gap size between skin and clothing, and the upper clothing aperture design. Furthermore, a local ventilation rate correction factor equation is developed as a function of the inter-segmental ventilation rate to correct for local ventilation rates when derived from values of isolated/unconnected clothed segments.

Factors Affecting the Achievement of Students in Economic Subject

2021 ◽  
Vol 12 (3) ◽  
pp. 1330-1336
Author(s):  
Siti Hadijah Che Mat Et.al
Keyword(s):  
Teaching Methods ◽  
Teaching And Learning ◽  
Mean Value ◽  
General Interest ◽  
Factors Affecting ◽  
Teaching And Learning Environment ◽  
Learning Techniques ◽  
Economic Program ◽  
The Subject ◽  
High Level

There are various factors influencing a student’s academic achievement at any level, either primary, secondary or tertiary. These factors include attitudes, learning techniques, general interest in the subject matter, factors related to teacher, family or friends, previous achievements, teaching and learning environment and facilities, infrastructure, and teaching methods. This article explores factors affecting the achievement of student of a course offered in the economic program of universitiutaramalaysia. For this article, a total of 220 students who registered for macroeconomics course at universitiutaramalaysia were randomly selected to be the study sample. of the 220 responses, only 211 were analysed because some questionnaire forms was returned with incomplete information. these students consist of second, third and fourth year students. The study found that among the items in the lecturer preparation factor which came with high mean scores is the item "lecturer shows dedication in teaching". There is no denying that teaching and learning methods incorporating the latest technology and trends are desirable but the study shows that teaching using longstanding approach like using whiteboards is still preferable among students and gives the highest mean value of 7.44, which is a high level score. In terms of learning techniques, the study found that students are not consistent between the goals to achieve excellence with the appropriate effort taken by them. although they want to achieve high excellence in this subject but their efforts and actions are not inclined to that desire

scholarly journals Drinking Water Fluoride Levels for a City in Northern Mexico (Durango) Determined Using a Direct Electrochemical Method and Their Potential Effects on Oral Health

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Nelly Molina Frechero ◽  
Leonor Sánchez Pérez ◽  
Enrique Castañeda Castaneira ◽  
Anastasio Oropeza Oropeza ◽  
Enrique Gaona ◽  
...  
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Water Distribution ◽  
Dental Fluorosis ◽  
Fluoride Concentration ◽  
Mean Value ◽  
National Standard ◽  
Preventative Measures ◽  
The Government ◽  
The City

Fluoride is ingested primarily through consuming drinking water. When drinking water contains fluoride concentrations >0.7 parts per million (ppm), consuming such water can be toxic to the human body; this toxicity is called “fluorosis.” Therefore, it is critical to determine the fluoride concentrations in drinking water. The objective of this study was to determine the fluoride concentration in the drinking water of the city of Durango. The wells that supply the drinking water distribution system for the city of Durango were studied. One hundred eighty-nine (189) water samples were analyzed, and the fluoride concentration in each sample was quantified as established by the law NMX-AA-077-SCFI-2001. The fluoride concentrations in such samples varied between 2.22 and 7.23 ppm with a 4.313 ± 1.318 ppm mean concentration. The highest values were observed in the northern area of the city, with a 5.001 ± 2.669 ppm mean value. The samples produced values that exceeded the national standard for fluoride in drinking water. Chronic exposure to fluoride at such concentrations produces harmful health effects, the first sign of which is dental fluorosis. Therefore, it is essential that the government authorities implement water defluoridation programs and take preventative measures to reduce the ingestion of this toxic halogen.

scholarly journals Practical Evidence-Based Evaluation of a Combined Heat Reduction Technique for Power Transformer Buildings

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2127
Author(s):  
İlker Dursun ◽  
Sıtkı Güner ◽  
İbrahim Şengör ◽  
Ayşe Kübra Erenoğlu ◽  
Ozan Erdinç ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Power Transformer ◽  
Reduction Technique ◽  
Evidence Based ◽  
Ambient Conditions ◽  
Factors Affecting ◽  
Operational Conditions ◽  
Effective Operation ◽  
Main Factors

Transformer buildings are at the heart of the effective operation of distribution systems, and heating problems of transformers under severe operational conditions are among the main factors affecting the lifetime, efficiency, technical losses, etc., of such important power system assets. It is crucial that the inside temperature of transformer buildings is higher than the outside temperature due to the operation of the transformer and the effect of ambient conditions. This issue may cause several problems such as additional transformer aging, losses, and moisture. The main purpose of this study is to decrease the inside temperature of transformer buildings; in other words, to prevent the inside temperature from being higher than the outside temperature. To realize this, it is recommended to apply a combined heat reduction technique by covering the outer surface with a reflective surface and use a low-emitting material on the inner surface. The relevant results of the practical evidence in this manner are presented in detail at a distribution system in Turkey with different climate and loading conditions in the summertime.

Ventilation inhomogeneity during controlled ventilation. Which index should be used?

1988 ◽  
Vol 65 (5) ◽  
pp. 2030-2039 ◽  
Author(s):  
A. Larsson ◽  
C. Jonmarker ◽  
O. Werner
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Mean Value ◽  
Mixing Ratio ◽  
Tracer Gas ◽  
Ventilation Inhomogeneity ◽  
Pulmonary Clearance ◽  
Significant Difference ◽  
Uneven Ventilation ◽  
Spontaneously Breathing

Six indexes for diagnosing uneven ventilation by tracer gas washout were studied. The indexes were lung clearance index, mixing ratio, Becklake index, multiple-breath alveolar mixing inefficiency, moment ratio, and pulmonary clearance delay, all of which increase with impaired pulmonary gas mixing. In model lung tests, indexes that compared the actual washout curve with a calculated ideal curve (mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay) were unaffected by changes in tidal volume and series dead space, whereas the others varied markedly. In both spontaneously breathing and mechanically ventilated patients all indexes showed a significant difference between smokers and nonsmokers (P less than 0.002), but the indexes were somewhat different in their assessment of different ventilatory patterns. However, the mean value for all indexes, with the exception of mixing ratio, was smallest with a fast insufflation followed by an end-inspiratory pause. Any of the indexes may be useful if its limitations are recognized, but mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay seem preferable, because they are not affected by changes in tidal volume and dead space fraction.

Ventilation of Wind-Permeable Clothed Cylinder Subject to Periodic Swinging Motion: Modeling and Experimentation

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
N. Ghaddar ◽  
K. Ghali ◽  
B. Jreije
Keyword(s):  
Cotton Fabric ◽  
Current Model ◽  
Ventilation Rate ◽  
External Pressure ◽  
Motion Modeling ◽  
Tracer Gas ◽  
Wind Speeds ◽  
Air Speed ◽  
Local Thermal Comfort ◽  
Ventilation Rates

Abstract A theoretical and experimental study has been performed to determine the ventilation induced by swinging motion and external wind for a fabric-covered cylinder of finite length representing a limb. The estimated ventilation rates are important in determining local thermal comfort. A model is developed to estimate the external pressure distribution resulting from the relative wind around the swinging clothed cylinder. A mass balance equation of the microclimate air layer is reduced to a pressure equation assuming laminar flow in axial and angular directions and that the air layer is lumped in the radial direction. The ventilation model predicts the total renewal rate during the swinging cycle. A good agreement was found between the predicted ventilation rates at swinging frequencies between 40rpm and 60rpm and measured values from experiments conducted in a controlled environmental chamber (air velocity is less than 0.05m∕s) and in a low speed wind tunnel (for air speed between 2m∕s and 6m∕s) using the tracer gas method to measure the total ventilation rate induced by the swinging motion of a cylinder covered with a cotton fabric for both closed and open aperture cases. A parametric study using the current model is performed on a cotton fabric to study the effect of wind on ventilation rates for a nonmoving clothed limb at wind speeds ranging from 0.5m∕sto8m∕s, the effect of a swinging limb in stagnant air at frequencies up to 80rpm, and the combined effect of wind and swinging motion on the ventilation rate. For a nonmoving limb, ventilation rate increases with external wind. In the absence of wind, the ventilation rate increases with increased swinging frequency.

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