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How To Accurately Judge Whether There Is Non Condensable Gas In Refrigeration System

Refrigeration system vacuum is not completely exhausted, it is easy to cause the air to exist in the system; today we will try to accurately determine whether the presence of non-condensable gas refrigeration system.

    In refrigeration systems, the non-condensable gases are mainly nitrogen, oxygen, hydrogen and moisture in the air. Since these refrigerants do not condense, these refrigerants generally accumulate in the condenser or accumulator.

    As the non-condensable gas occupies part of the condensing space, it will cause the condensing pressure (exhaust pressure) increases, so that the pointer of the compressor jitter, reducing the cooling effect and the compressor power consumption;

    Therefore, most of our refrigeration workers are judging the presence of air inside the refrigeration system based on the jitter of the high pressure gauge.

    However, for Freon systems, it is unscientific to judge the non-condensable gas by high-pressure pressure gauge jitter alone, because there are many reasons for the jitter of high pressure gauges, for example:

    1, the exhaust valve deformation (piston compressor)

    2, the system flash, resulting in throttle shocks, condensation pressure may occur shock;

    3, expansion valve failure

    Therefore, high-pressure jitter jitter, can not be identified on the system there is non-condensable gases exist.


    Second, determine the principle

    According to Dalton's law of partial pressure of gas, the absolute pressure in a closed container is equal to the sum of the partial pressure of each existing gas, so we assume that the pressure inside the condenser and accumulator is equal to the condensing pressure of the refrigerant plus the non-condensable gas The sum of the pressure. Therefore, if there is non-condensable gas in the system, the pressure will inevitably be high. We can also determine whether there is non-condensable gas in the system by measuring the temperature and pressure.

    Here we divided air-cooled and water-cooled condenser to introduce how to determine the existence of non-condensable gas system

  

  Third, air-cooled

    Connect a thermometer to the exit of the air-cooled condenser and stop the compressor. Close the exhaust valve and the supply valve. Wait quietly. When the degree of this thermometer is the same as the number of thermometers in another measured air temperature Very close), please record the pressure in the condenser at this time, and the temperature corresponding to the ambient temperature under the saturation temperature, if the former is higher than the latter, you can basically determine the existence of non-condensable gas inside the system.

  

   Fourth, water-cooled

 Take a thermometer at the outlet of the water-cooled condenser, stop the compressor and close the exhaust valve and the liquid supply valve. At this time, the cooling water is normally on and running.

    In the cooling water import and export respectively, then the thermometer, measuring the water temperature, quietly waiting; when the inlet and outlet water temperature is equal, please record the pressure inside the condenser and water-cooled condenser exit temperature, if the condenser condensing pressure is high At the saturation pressure corresponding to the outlet temperature, we can determine that there is a non-condensable gas in the system, and the greater the difference between the two, the more non-condensable gases.

 

    Fifth, the actual case

    Read the above so much, but you have not understood, take a look at the following actual examples:

    E.g:

    The measured condensing pressure of R22 system is 13.2kg / cm2 (gauge pressure), when the ambient temperature is 35 degrees.

    Check the "R22 refrigerant temperature and pressure table", the corresponding temperature of 35 degrees when the pressure is 12.81kg / cm2 (gauge pressure), lower than the measured condensation pressure, indicating the presence of non-condensable gases in the system. The pressure of non-condensable gases is:

    13.2-12.81 = 0.39 kg / cm2 (gauge pressure).

    This method of discrimination and detection is very simple, very practical and practical.


    Six, the system has non-condensable gas separator

    For large ammonia refrigeration systems, there is usually a non-condensable gas separator;

    Noncondensable gas easily at low temperatures, the system standing state and natural separation of refrigerant, its specific gravity than the refrigerant small, gathered in the system after the high (above), so you should choose the lowest temperature in the period, The longest system downtime, the highest point of discharge system emissions. You can also open the valve directly from the top of a container in the system to discharge, or sub-container discharge one by one line.


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