Refrigeration in aeroplanes usually employs the following refrigerant___________________?
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Answer: D. Air
Explanation
Air conditioning and refrigeration systems in aeroplanes use plain air as the working refrigerant due to safety and weight. Using air eliminates the hazards associated with toxic or flammable chemical refrigerants inside pressurized passenger cabins. Bleed air extracted from aircraft gas turbine compressors provides a readily available source for the air-cycle cooling system. Aircraft environmental control systems require lightweight, highly reliable cooling equipment operating in extreme flight conditions. Air cycle machines combine compressors, heat exchangers, and expansion turbines in a compact, highly integrated assembly. The high pressure of jet engine bleed air makes it an ideal medium for expanding and cooling passenger cabin air.
Option A carbon dioxide is rarely used in standard aircraft air conditioning due to high operating pressure requirements. Option B Freon-11 is a chemical refrigerant restricted in modern aviation due to environmental ozone depletion regulations. Option C Freon-22 is utilized in stationary commercial air conditioning rather than lightweight aircraft environmental control loops.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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