Why do we use Cascade Refrigeration Systems?

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Discussion Overview

The discussion revolves around the efficiency of Cascade Refrigeration Systems compared to traditional refrigeration systems. Participants explore the reasons behind the perceived efficiency gains, focusing on phase changes and the thermodynamic principles involved.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that Cascade Refrigeration Systems are more efficient due to the multiple phase changes from gas to liquid, suggesting that having two phase changes (or "bumps") is beneficial for efficiency.
  • One participant elaborates that the efficiency gain occurs because the phase change from gas to liquid involves a significant heat absorption, while the transition from gas to a thinner gas is less effective, leading to a preference for using different gases in the system.
  • Another participant expresses confusion regarding the initial explanation, indicating a need for clearer communication about the efficiency mechanisms at play.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the efficiency of Cascade Refrigeration Systems, with some agreeing on the role of phase changes while others seek clarification on the explanations provided. The discussion remains unresolved with multiple viewpoints presented.

Contextual Notes

Some assumptions about the efficiency mechanisms and the specific temperature and pressure ranges that contribute to the effectiveness of the systems remain unaddressed, leading to potential gaps in understanding.

Yousef Dajani
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I know that the Cascade Refrigeration Systems are more efficient than the normal Refrigeration Systems, but I still don't know why?
 
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My thought is that you have an effective bump in efficiency at phase change from gas to liquid and the farther you get from the bump the less efficient... So two bumps is better
 
Andy SV said:
My thought is that you have an effective bump in efficiency at phase change from gas to liquid and the farther you get from the bump the less efficient... So two bumps is better
I don't understand your opinion
 
Big sigh ... Yea I get that a lot
 
Ok so I will try to rephrase with more clarity.
Change from let's say liquid propane to a gas eats heat. But a change from gas to a thinner gas does to just not as much. Compression of that gas to a denser gas forces out the heat but not as much as compression of the propane to a liquid. So the temperature pressure range closer to where it changes phase is more efficient at moving heat. But that is not a wide range. So you get a different gas like carbon dioxide and cool it with the propane now it's a lot easier to concentrate condense into a liquid and you can stay in the temperature band that it is efficient in.
I hope that is better
 

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