Hello everyone, satellite temperature?

[Phase8]

I need a lamens definition for what a satellite temperature is and why it would be needed.
Thank you.

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[jpsmith1cm]

A satellite is an additional portion of the machine that runs at a slightly higher or lower suction pressure.

Typically, the idea is to save energy by only using the capacity that is required to maintain the colder temps or by grouping the higher temperature circuits together and running them at a higher pressure.

[Phase8]

So the freezer in a rack would be a separate circuit from the coolers?

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[jpsmith1cm]

So the freezer in a rack would be a separate circuit from the coolers?

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Actually, the freezers would typically be a different rack.

Think ice cream cases vs frozen food cases.

Ice cream runs a bit colder, but there is typically only a few of them as opposed to frozen.

So, we'd set up a satellite to keep the ice cream at a lower suction temperature.

[Phase8]

So in terms of diagnosis satellite means nothing it technically is its own system?

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[mspanky]

So in terms of diagnosis satellite means nothing it technically is its own system?

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No, a satellite runs it's own suction pressure but shares a common discharge line, condenser, and receiver with other compressors. (rack)

[Joe Harper]

In smaller stores you would have one rack, with low and med tem circuits. The med circuits are controlled by an evap pressure regulator. Could be a sorit, stepper valve, or an ORI.

Since the frame pressure on a 404 low remp rack is around 17-20 psi, you can run a med temp circuit at 60 psi by regulating the applied suction pressure.

[Phase8]

Wow, now I think I can understand it enough to explain it. Thanks everyone.

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[jpsmith1cm]

In smaller stores you would have one rack, with low and med tem circuits. The med circuits are controlled by an evap pressure regulator. Could be a sorit, stepper valve, or an ORI.

Since the frame pressure on a 404 low remp rack is around 17-20 psi, you can run a med temp circuit at 60 psi by regulating the applied suction pressure.

A lot of times, we install a split rack for this application. Loop the liquid line and suction lines and put steppers at the cases.

The little stores LOVE 'em. Save them a ton of money over a dozen singles.

[bunny]

I'm sure you understand compression ratio: The ratio of absolute discharge to absolute suction (with absolute being gauge pressure + 14.7, if at sea level).

The higher the compression ratio, the less efficient the compressor is. This has to do with the amount of piston travel needed to re-expand the vapor that is trapped in the clearance between the top of the piston and the bottom of the valve plate.

So, if you can isolate the system operating at the lowest saturated suction temperature by piping it to its own compressor (the satellite compressor), the remainder of the compressors on the rack can operate at a higher saturated suction temperature, meaning more efficiently. No need to operate the entire rack at -25 SST to satisfy the 24' of ice cream cases. Use a satellite for this, and operate the rest of the rack at whatever the FF cases require...say -15 SST. This translates into less $$ on the power bill at the end of the month.

Here's an example:

A 3D compressor operating at -25 SST and 105 SCT has a capacity of 46,300 Btu. The same compressor operating at a -20 SST and 105 SCT has a condenser 50,500 Btu. That's a 10 increase in capacity, simply by operating at a higher SST.

This is why satellite compressors are employed.

[Jonnyb]

Never see that ? Run a complete low temp rack for medium circuit. For dual temp case ok but not fresh meat.

[Phase8]

Why not fresh meat, why would there be a difference?

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[Jonnyb]

For the post #7
If you have a rack with medium and low temp, you will have to succion group with low temp compressor and medium temp compressor