Refrigeration 101

[Fett]

In order for the subcooling to be 15F/8.5K the liquid must travel through an area where the temperature is at least 15F/8.5K below the SCT or the desired subcooling cannot be achieved.

If the receiver outlet is directly in the path of the air leaving the condenser, then the surrounding air is not cool enough to sufficiently subcool the liquid.

In this case, the liquid line temperature must be measured further downstream where the surrounding air is cooler.

Hey Gary,

Would it be incorrect to measure the liquid line temperature a few inches upstream from the TXV/TEV?

It would seem to me that area would be a good spot to measure, but I could be wrong.

[Gary]

Hey Gary,

Would it be incorrect to measure the liquid line temperature a few inches upstream from the TXV/TEV?

It would seem to me that area would be a good spot to measure, but I could be wrong.

No, it would not be incorrect, but it may not tell you what you need to know.

The ideal is to have solid liquid at the TXV inlet, but to not back liquid up into the condenser.

Since there is solid liquid at 10-15F/5.5-8.5K SC, we can tell where along the liquid line there is solid liquid and where there is excess SC.

Excess SC is fine at the TXV inlet, but if there is excess SC at the receiver outlet, then we start backing liquid up into the condenser, which drives up the high side pressure.

Measuring SC at the TXV inlet can tell you if there is sufficient refrigerant to feed the coil, but it doesn't tell you if the system is overcharged. That's why I want to check it closer to the receiver.

[nike123]

Some terminology clarification:
http://sporlan.jandrewschoen.com/Col...erminology.pdf

http://sporlan.jandrewschoen.com/Col...00%20Terms.pdf