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[Video] How High Ambient Temps Affect a Sealed System


Son of Samurai

1,699 views

In this video, we give a comprehensive answer to this question: "Why is it that high ambient temps cause high side and low side pressures to rise?"

This simple question about one specific sealed system problem scenario is a great opportunity to take a deeper dive into how sealed systems work, how they're affected by their environment, and how an issue in one area of a sealed system has ramifications for every other area.

Topics covered include:

  • The temperature/pressure relationship at saturation
  • Compression ratios
  • Volumetric efficiency
  • Starved evaporator symptoms

...and more!

Click here to watch the video -- available only to tech members at Appliantology.

Screenshot 2023-06-17 at 1.13.32 PM.png

 

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Koi Guy

Posted (edited)

Awesome Sam-san. I'm starting to catch a little bit of it. :) 

Question: I'm wondering what passive condenser units would look like on the PH chart. The case I'm thinking of would be something like an upright freezer with condenser built into the cabinet. I was initially thing that it would just have low efficiency in the valve chamber- but that can't be right. So then I thought maybe compressor design or btu, but just not sure. Or maybe there's nothing done and it's just inefficient. None of my answers seem right. 

To add to my thoughts, I know that Whirlpool under the counter ice machines 15" and 24" use the same evaporator coil, same condenser, yet have different compressors and charge weight. So I know there's a btu relationship, but don't know how it applies. 

Domo!

Edit: Oh I was just thinking- Frigidaire has built in units that are separate freezer and refrigerator (knock off SubZ's). They use the same evap, same heat exchanger, and same condenser- just a different compressor and charge weight. So it's like the WPL IM- same guts but different heart.

Edited by Koi Guy
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Son of Samurai

Posted

On 6/21/2023 at 9:13 AM, Koi Guy said:

Question: I'm wondering what passive condenser units would look like on the PH chart. The case I'm thinking of would be something like an upright freezer with condenser built into the cabinet. I was initially thing that it would just have low efficiency in the valve chamber- but that can't be right. So then I thought maybe compressor design or btu, but just not sure. Or maybe there's nothing done and it's just inefficient. None of my answers seem right. 

You've pretty much got your finger on it. The P-H chart wouldn't really look different on a passive condenser unit, because the engineers would adjust factors to compensate for the slower heat dissipation. Specifically, they can adjust the capacity of the compressor or the amount of refrigerant in the system.

It all comes down to how many BTUs/hour the system can move. And that's directly affected by how much refrigerant is in the system. More refrigerant = more capacity to absorb heat, since heat is just molecular vibration. The more molecules you have that can vibrate, the more heat you can store.  BTUs/hour is also affected by how much of the refrigerant gets moved through the system with each stroke of the compressor.

There's a lot of math involved here that we don't need to get into. It's enough that we can understand in general terms that engineers can adjust one or both of these parameters to make the system meet their needs.

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Good stuff...Excited to learn more about this will re-watch this many times!!!

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