2014-02-17
357
Replacing ozone-depleting refrigerants
Exercise 3. Read and translate the text.
TEXT 2
Exercise 11. Speak about chilling and refrigeration as the most effective methods of fish preservation nowadays.
Exercise 1. a) Read and translate international words without a dictionary:
ozone, equivalent, unique, protocol, influence, to influence, absolutely, engineer, category, classify, toxicity, toxical, compressor, economizer, operation, risk, to risk, to initiate, initiative, limit, to limit, technical, system, coefficient, project, substance, hygroscopic.
b) Check if you remember the meaning of these words:
mixture, layer, discovery, replacement, obvious, pure, media, odour, compound, chlorine, carbon.
c) Read and translate the following word combinations:
the scientific magazine, chemical composition, the long-term solution, an extensive programme, absolutely free from, the ozone layer, global warming, chlorine-free refrigerants.
Exercise 2. a) Read and memorize the abbreviations from the text below:
| CFC | фреон (от chlorofluorocarbon) |
| HCFC | от hydrochlorofluorocarbon |
| HFC | от hydrofluorocarbon |
| R | хладагент (от refrigerant) |
| ASHRAСE | the American Society of Heating, Refrigeration andAir Conditioning Engineers |
| STAL | an extensive programme initiated by the Air Conditioning and Refrigeration Institute in the USA participating actively in the European part of that programme |
b) Read and memorize the words from the text below:
| rate, v | считать; расценивать; рассматривать |
| flammability, n | воспламеняемость |
| explosive, adj | взрывчатый |
| achieve, v | добиваться, достигать |
| solution, n | решение |
| performance, n | выполнение |
| depletion, n | уменьшение, истощение |
| substitute, n | заместитель, заменитель |
| convert, v | превращать |
The scientific magazine "Nature" reported that the ozone layer over the Antarctic – an area equivalent to the size of the United States – had been reduced by 50 to 60 per cent during the winter. This discovery led to a unique international drive against ozone layer depletion. The first step was the signing of the Montreal Protocol with the aim of reducing CFC production by 50 per cent and then stopping production completely by 2010. However, depletion of the ozone layer was faster than foreseen.
What are the alternatives? It is obvious that CFC replacements based on HCFC compounds are only temporary solutions, likely in exist for a 10 year period. Instead, refrigerants with no influence on the ozone layer at all will be the long-term solution. Their chemical composition must thus be absolutely free from chlorine. The American Society of Heating, Refrigeration andAir Conditioning Engineers (ASHRAСE) recently classified the refrigerant R134a in the category chlorine-free refrigerants: HFCs. Like R12 and R22, R134a is rated in the lowest risk class regarding toxicity and flammability. R134a is primarily a substitute for R12 and R500, and is now an established alternative. Its coefficient of performance is close to – or the same as – that of a circuit process with R12. Sub-cooling is favourable with R134a and plants using, for instance, screw compressors with economizer operation can be converted advantageously from R12 to R134a.
