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    high discharge temperature



    Hello
    Among some causes of too high discharge temperature in many articles there is mentioned low suction pressure. Among some causes of the LSP are named : low evaporator heat loads; frosted evaporator coils; evaporator fan out. How can the latter ones lead to increase of the discharge temperature ?



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    Re: high discharge temperature

    Quote Originally Posted by Yuri B. View Post
    Hello
    Among some causes of too high discharge temperature in many articles there is mentioned low suction pressure. Among some causes of the LSP are named : low evaporator heat loads; frosted evaporator coils; evaporator fan out. How can the latter ones lead to increase of the discharge temperature ?

    Yuri,
    Possibly higher compression ratio as well as suction gas not cooling cylinders due to high superheat.
    The suction gas is also less dense.
    Mainly an issue with reciprocating compressors.

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    Re: high discharge temperature

    Hi, Yuri B

    Quote Originally Posted by Yuri B. View Post
    Hello
    Among some causes of too high discharge temperature in many articles there is mentioned low suction pressure. Among some causes of the LSP are named : low evaporator heat loads; frosted evaporator coils; evaporator fan out. How can the latter ones lead to increase of the discharge temperature ?
    See this... link within passandscore answer .. a good article

    http://www.refrigeration-engineer.co...rge-temprature


    Best regards, Josip

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    Re: high discharge temperature

    Thank you for your answers !
    But, the suction SH cannot be high, the returning gas is cool, with a capillary expansion device the gas is dense, the motor does less work and is less loaded, why the DT should increase ? The article does not explain this .

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    Re: high discharge temperature

    Quote Originally Posted by Yuri B. View Post
    Thank you for your answers !
    But, the suction SH cannot be high, the returning gas is cool, with a capillary expansion device the gas is dense, the motor does less work and is less loaded, why the DT should increase ? The article does not explain this .
    I think it suggests compression ratio & volumetric efficiency. YOu say cool gas returning, but what is superheat & pressures at that time. Every situation is different so these are basic reasons. If you have a real life scenario we could be able to anylize things better. Leaking valves is another option.

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    Re: high discharge temperature

    Quote Originally Posted by Yuri B. View Post
    Thank you for your answers !
    But, the suction SH cannot be high, the returning gas is cool, with a capillary expansion device the gas is dense, the motor does less work and is less loaded, why the DT should increase ? The article does not explain this .
    Have you check your system is perfect vacuum? Non condensable (air) will cause to increase the discharge temperature.

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    Re: high discharge temperature

    Cpillar tube based systems shoud have the exact amount of refrigerant.

    Air in the system, partialy blocked drier, over charged system will raise the discharge pressure\temperature.

    you should recover the gas, replace drier, weigh the righe amount of refrigerant in.

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    Re: high discharge temperature

    I should say I did not mean a particular case to resolve.
    Last edited by Yuri B.; 04-08-2013 at 06:19 PM.

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    Re: high discharge temperature

    Hi, Yuri B.

    Quote Originally Posted by Yuri B. View Post
    I should say I did not mean a particular case to resolve.
    In attached document, please, try to find your case ....


    Troubleshooting Mollier chart.pdf


    Best regards, Josip

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    Re: high discharge temperature

    If the discharge temperature elevates without rise the inlet superheat, this would indicate the problem of compressor mechanical trouble.

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    Re: high discharge temperature

    Yes, and the efficiency - already mentioned here - drops in this case. However, worn out valves and what else is something different than "low load".
    Last edited by Yuri B.; 09-08-2013 at 07:00 PM.

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