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Sources of Air Pollution
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
Ozone in the stratosphere protects the earth from the UV fraction of solar radiation. Certain chemicals such as chlorofluorocarbons (CFCs) can bind the ozone in an atmospheric reaction and deplete this protective layer.
Future Power Generation And the Environment
Published in Anco S. Blazev, Power Generation and the Environment, 2021
Thermoelectricity is the new process that can convert heat directly into electric energy in a device with no moving parts. Although the device is still on the computer desktops, it can be built with the characteristics that are seen in our simulations. When built, this device will use waste heat to generate electric power, which has multiple advantages. It will eliminate ozone-depleting material by increasing the efficiency of cars, power plants, factories, and solar panels, thus making ozone-depleting chlorofluorocarbons, or CFCs, outdated.
Optical Liquids
Published in Marvin J. Weber, and TECHNOLOGY, 2020
At one time PCB (polychlorinated biphenyl) materials were common in optical liquids because of their high stability. Due to government and academic concerns, PCB-containing optical liquids were discontinued. For example, all PCB materials were replaced in all Cargille Optical Liquids by 1978. CFCs (chlorofluorocarbons) of low molecular weight commonly used as refrigerants and aerosol propellents are considered a threat to the ozone in the atmosphere and are to be phased out of use. Some commercial optical liquids contain CFC. A few Cargille liquids contain CFCs, but they are CFCs of high molecular weight, are not a hazard to the ozone layer, and are not subject to the phase out. In general, optical liquids are used in such small quantities that they do not threaten the environment.
Performance analysis in the design of thermoacoustic refrigeration system: review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Sajid Hameed Siddiqui, Akash Langde
Although various techniques have been used to improve the standard of thermoacoustic refrigeration systems, there is always a need to reduce the time consumption and cost and increase the COP of the system. In the future, thermoacoustics refrigeration has the potential to replace the current vapor compression refrigeration technique. Furthermore, it minimizes the release of hazardous chemicals into the environment, such as chlorofluorocarbons (CFCS) and hydrofluorocarbons (HFCS), which contribute to global warming and ozone depletion. In the future, the researchers should enhance the components of TAR like resonator tubes, stack, and medium fluid. Additionally, the influence of gases with high adiabatic index (k) and specific gas constant (R) on acoustic velocity must be examined in future research. Also, to enhance the cooling load and the COP of the system, the rate of heat transmission between the stack and the heat exchangers can be increased. There are some limitations, the produced cooling power in existing techniques is extremely low, and this technology requires more exploration in several areas. Lesser coefficient of performance in COP and vapor compression cycle (VCR). Aforementioned inherent dependability, the lack of moving components, and the use of working fluids that is not detrimental to the environment, such as Argon, Helium, and others. Moreover, the acoustic velocity may be enhanced by utilizing a convergent-divergent section, resulting in a reduction in sound intensity, input power, and an increase in the COP of the system.
Electron ionisation cross sections of CF3Cl and CF2Cl2 molecules
Published in Molecular Physics, 2022
Pawan Kumar Sharma, Rajeev Kumar
Worldwide industrial use of freons (Chlorofluorocarbons) like CF3Cl, CF2Cl2 etc. as refrigerants, solvents, agents used for foam blowing and aerosol propellants has drawn serious attention due to catalytic decomposition of atmospheric ozone resulting in depletion of the ozone layer in the stratosphere. The ozone layer acts as a shield for the earth’s environment from UV solar radiation known for disastrous effects [1–3] causing various skin hazards. Dissociation of chlorine from freons due to UV solar radiation sets off a chain reaction that changes ozone into oxygen more readily than fluorine radicals which causes a chain ending reaction for ozone depletion and hence can be considered less destructive [3]. The study of electron ionisation cross-section becomes a significant tool to understand the direct and dissociative ionisation behaviours of freons and also has remarkable use in industry and study of low-temperature plasma similar to as produced by solar winds in the stratosphere due to low energy electron release.
Short-term variability of total column ozone from the Dobson spectrophotometer measurements at Belsk, Poland, in the period 23 March 1963–31 December 2019
Published in Tellus B: Chemical and Physical Meteorology, 2021
J. W. Krzyścin, B. Rajewska-Więch, J. Borkowski
In response to the threat of ozone destruction, the Montreal Protocol (MP) was signed in 1987, which established restrictions on the production of the most ozone depleting substances (ODS) (e.g. chlorofluorocarbons – CFC) containing chlorine and bromine, which are involved in the catalytic destruction of the stratospheric ozone shield against the UV radiation. Ground-based monitoring of the ozone layer with Dobson spectrophotometers played a decisive role in the discovery of the Antarctic ozone hole and led to the identification (in the beginning of 1990s) of significant long-term ozone depletion in winter and spring over extratropical regions (Staehelin et al., 2018 and the references therein). Establishing a world standard for the Dobson instrument (Dobson spectrophotometer No. 83) was decisive for maintaining the high quality of the global Dobson network (Komhyr et al., 1989).