Correct Answer - Option 2 : high viscosity
Explanation:
Secondary refrigerants:
Usually, liquids and air are used to transfer heat from the substance being cooled to a heat exchanger where the heat is absorbed by a primary refrigerant. In an air conditioning system, it could be said that air is acting as a secondary refrigerant.
Properties of Refrigerants:
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Low freezing point: When the refrigerant goes through the expansion valve in the refrigeration cycle, it experiences a tremendous pressure drop and hence a tremendous decrease in temperature as well. It is therefore important that the refrigerant has a low freezing point than the normal operating conditions.
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Low viscosity: For the easy flow of refrigerants.
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Good stability: It should be chemically stable for the operating ranges of temperature. Also, it should not react with the materials of the refrigeration system or with which it comes into contact.
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Low vapor pressure: Condenser pressure of the refrigerator should be moderate and the evaporator pressure of the refrigerator should be around atmospheric pressure.
Other Important Properties of Refrigerants:
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Thermodynamic Properties
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Chemical Properties
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Physical Properties
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High Critical Temperature
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Non-Toxic
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Low Viscosity
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Specific heat of vapor should be high.
Specific heat of liquid should be low.
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Non-Flammable
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Leak detection
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Freon leaks is detected by Halide Torch Test
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Ammonia leaks is detected by sulpher stick method.
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SO2 detected by ammonia swab Test.
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High enthalpy of Vaporization
Lower compression Ratio is Required
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Action with the material of construction
Wrought Iron is favorable with ammonia
Copper is favorable with Freon.
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Low Cost
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Freezing Point should be low.
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Miscibility with oils.
Oil separator is installed between the compressor and condenser.
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Conductivity should be high
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