another major environmental concern (Figure 3-2). Do not confuse ozone depletion with global warming. These are two entirely different environmental problems. When compared to ozone depletion, the use of refrigerants contributes very little to the overall global warming problem.
Global warming occurs as a result o f the pollutants present within the Earth’s troposphere. Included among the pollutants are elements o f refrigerants, tropospheric ozone or smog, fog, carbon dioxide, carbon monoxide, and sulphur oxide. Refrigerants have little direct effect on the global warming process. It is carbon dioxide which is considered to be the most harmful element contributing to global warming. Sulphur oxide and carbon monoxide are also major contributors.
Global warming occurs because the pollutants in the troposphere absorb heat and act as reflectors. Infrared radiation emitted from the Earth is reflected back to the Earth instead o f passing through the troposphere and stratosphere, then into outer space. The result is a gradual increase in the average temperature levels on Earth. As the levels of pollution in the troposphere increase, global warming also increases.
Scientists are concerned that increased global warming will cause the polar ice caps and glaciers to melt, substantially increasing water levels on the Earth. Global warming can also result in decreased crop yields, added smog levels, and changes in climatic patterns.
A measure of the ability of a refrigerant to directly contribute to global warming is called its Global Warming Potential (GWP). The GWP values of ail refrigerants are compared to CFC-11, which has a GWP of 1. Again, the lower the number, the less harmful the refrigerant is to the environment. Some common GWP values for refrigerants are:
Some newer alternate and replacement refrigerants can contribute indirectly to global warming. Typically, these refrigerants are less efficient than the older, environmentally-harmful refrigerants. This means the equipment that uses the newer refrigerants consumes more electrical power in order to provide the same amount of cooling capacity.
T h e increased demand for e le c tric ity caused by the equipment’s inefficiency means that more fossil fuels are burned by the utility companies in order to generate the electricity (Figure 3-3). More carbon dioxide is being generated and released into the troposphere as a by-product of the combustion process- Th is further increases the pollution in the troposphere, thereby causing an increase in global warming. In HVAC applications, it is this indirect pollution resulting from equipment inefficiency that has the greatest effect on global warming.
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