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Evaluation Tools and Techniques
Published in David W. Bearg, Indoor Air Quality and HVAC Systems, 2019
Air current tubes, or “smoke sticks” or “smoke pencils” as some people may call them, function by creating a visual plume in the air which then permits the direction and relative velocity of any air movement to be visually detected. One such device, the Dräger Air Current Kit, uses glass tubes filled with fuming sulfuric acid. They work by pulsing room air through the tube to create a visible acid vapor cloud from the reaction of the moisture in the air with the acid. Appropriate caution should therefore be employed when using this otherwise very useful tool because the contents are highly corrosive. Another similar device uses titanium tetrachloride, the visible cloud from which contains hydrochloric acid. Again, an appropriate amount of caution is indicated to keep the fumes away from people’s breathing zones, especially your own. Although these devices involve small releases of acid, I still consider them more appropriate to use than a burning punk or cigarette. Not only does the smoke from a cigarette contain 4,000 compounds, several of which are carcinogenic, but also its smoke is heated, is thermally buoyant, and will tend to create its own rising air currents. The air current tubes, which rely largely on the moisture already in thermal equilibrium with the space, will be thermally neutral and can show evidence of downward motion where it exists.
How we experience indoor and outside climates
Published in Karl H.E. Kroemer, Fitting the Human, 2017
A convenient way to assess the existent climate is to combine a set of special measurement instruments in one device, which weighs the separate measurement results according to their effects on the human body and from there derives a single index. The currently used version is the so-called Wet Bulb Globe Temperature, abbreviated WBGT. It primarily applies to warm environments and weighs the effects of several climate parameters: WB is the wet bulb temperature of a sensor with a wet wick exposed to natural air current.GT is the globe temperature at the center of a black sphere of 150 mm diameter.DB is the dry bulb air temperature.
Sewage sludge disposal on land – impacts on surface water quality
Published in R. Hranova, Diffuse Pollution of Water Resources, 2005
In attached growth systems (Fig. 8.1) the biological culture, known as “biofilm”, is attached to a fixed media, which could consist of natural material – stone or gravel, or plastic blocks with a high specific surface area. The reactor, where the process takes place is known as trickling filter (biofilter). The wastewater is spread over the filter media and on its way through it, gets in contact with the biofilm. The air current, formed due to the temperature difference between the reactor and the surrounding environment, supplies oxygen for the process. Figure 8.1 shows a treatment scheme commonly used in the region.
Effect of physical and subsequent processing parameters of glass fiber felts on sound insulation
Published in The Journal of The Textile Institute, 2018
Yong Yang, Zhaofeng Chen, Yingxin Chen, Lei Zhang, Hongwei Lu
Glass fiber felts which made from pure glass fiber and phenol resin adhesive were produced by centrifugal-spinneret-blow system (CSBS). The schematic diagram of CSBS process is shown in Figure 1. Vitreous fluid flows out from the leak board and forms a vitreous fluid stream; then the vitreous fluid stream will fall vertically into a centrifuge pan which rotates in high speed. The primary glass fibers are formed through pores on pan’s surrounding wall by making use of centrifugal force. These high-temperature primary fibers are immediately affected by air current jetted from ring-form combustion nozzles arranged concentrically with the centrifugal pan, and then further split and stretch into secondary fibers, namely, glass fiber (Liu, 2002; Yang et al., 2015). Glass fibers with phenol resin adhesive sent into curing oven to form glass fiber felts.
Energy performance enhancement of PV system through proposed back cooling techniques and natural air draft: an experimental study
Published in International Journal of Green Energy, 2023
Ahmed Osama Mahmoud Bedair, Ahmed S. Shehata, Mostafa S. Hamad, Adel Tawfik
The basic configuration consists of three PV modules placed side by side with a system of pipes on the rear that inject water from top to bottom. In an alternative method, two air blowers with respective ratings of 50 and 90 watts are used to provide the forced air current at the tunnel (the rear of the panel assembly). Water will be fed into the Panel’s topside through its topside, which will be packed with foam fabric to allow it to absorb water. The wet foam will directly interact with the driven air current produced by the air blower as it passes through the air tunnel, which will lower the temperature of the panel’s backside. The entire panel will begin to cool down gradually. The output of solar panels is determined using a straightforward formula.
Small-angle measurement in laser autocollimation based on a common-path compensation method
Published in Journal of Modern Optics, 2019
Yan Guo, Haobo Cheng, Yongfu Wen, Hengyu Wu, Yumin Wu
Among the many air parameters leading to the beam drift, the temperature is dominant according to the Edlen formula (25). A heat source can generate a circular temperature gradient field around itself. The closer the heat source is, the faster the refractive index of the air medium changes. When a light beam passes near a heat source, the direction of the beam will bend with the change of the refractive index, and then the drift will occur. To test the compensation effect for the temperature-induced drift, the electric fan was turned off and replaced by a soldering iron. The experiment was performed as soon as the soldering iron was energized. The soldering iron was slowly heated to 200°C in the first 40 min, and then a fluctuation range of ±1°C was maintained over the next hour. The compensation results are presented in Figure 8. In the first 40 min, the red drift curves shown in Figure 8(a) and (b) significantly increased or decreased by approximately 3 arcsec, and then changed in a relatively gentle manner by less than 2 arcsec. Throughout the measurement process, the PV values of the angular drift of the TM in the x- and y-directions were 3.581 and 5.137 arcsec before compensation, while 0.154 and 0.193 arcsec after compensation, respectively. It can be seen that the angular drift caused by temperature was more severe than that caused by the air current, particularly in the y-direction. With compensation, the measurement stability was increased by 95.7% and 96.2% in the x- and y-directions, respectively. In this experiment, the compensation rates were higher than those in the air current experiment.