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St1cks t1_j190ivz wrote

Reply to comment by zebediah49 in Why do we use phase change refrigerants? by samskiter

The compressor doesn't cause the lower pressure side on its own. We use a type of metering device to achieve a flash off within the suction line. Ideally a 25/75 mix of liquid and gas should be present at the start of the evaporator coil. Metering devices can be fixed or adjusting, which generally use a sensing bulb attached at the inlet of the evaporator.

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zebediah49 t1_j191who wrote

This is true; you need some type of pressure drop device.

I give disproportionate credit to the compressor, due to it being the part that does the Work.

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exbm t1_j19rjrr wrote

You need to use a compressor some types of systems use external heat but all systems need a flow restricting device

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zebediah49 t1_j1a0qqf wrote

Strictly speaking many external-heat systems don't. They use an absorption refrigeration cycle, and while the partial pressure of the refrigerant components changes around, the total pressure of the system is approximately constant.

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