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 ?

Quote:

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Originally Posted by Yuri B.

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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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.

Hi, Yuri B

Quote:

---

Originally Posted by Yuri B.

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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See this... link within passandscore answer .. a good article

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


Best regards, Josip :)

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 :confused:.

Quote:

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Originally Posted by Yuri B.

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 :confused:.

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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.

Quote:

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Originally Posted by Yuri B.

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 :confused:.

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Have you check your system is perfect vacuum? Non condensable (air) will cause to increase the 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.

I should say I did not mean a particular case to resolve.

Hi, Yuri B. :)

Quote:

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Originally Posted by Yuri B.

I should say I did not mean a particular case to resolve.

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In attached document, please, try to find your case ....


Attachment 10612


Best regards, Josip :)

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

Yes, and the efficiency - already mentioned here - drops in this case. However, worn out valves and what else is something different than "low load".