Heat pumps: Questions about compressor pump refrigerant gas and evaporator

[GreenWombat]

TL;DR Summary

A heat pump is a sealed unit that contains the refrigerant within a constant volume. How does the compressor increase the pressure within the high-pressure compressor and condensation spaces? Does it do this by pumping refrigerant gas from the evaporator and into the high-pressure space? Is this part of why the refrigerant in the evaporator gets cold?

A heat pump is a sealed unit that contains the refrigerant within a constant volume. How does the compressor increase the pressure within the high-pressure compressor and condensation spaces? Does it do this by pumping refrigerant gas from the evaporator and into the high-pressure space? Is this part of why the refrigerant in the evaporator gets cold?

I am retired from work and exploring hot-water heat pumps using propane as a refrigerant. I have many questions. Is it best to pose these questions individually in this thermodynamics forum?

 

[berkeman]

I am retired from work and exploring hot-water heat pumps using propane as a refrigerant. I have many questions. Is it best to pose these questions individually in this thermodynamics forum?

It's probably best to start with this question and see how the thread goes. These questions can go either here in the Thermo forum or in the Mechanical Engineering forum. PM a Mentor if you want a thread moved.

It would also help if you could post more about where you are in understanding heat pumps, and give links to the reading you've been doing about them. Thanks.

 

[GreenWombat]

I completed 4 years of science, including a thermodynamics unit, but that was way back. I am refamiliarising myself with things like latent heat and specific heat capacity.

I’ve found Wikipedia helpful and have questions about the Wikipedia pressure-volume diagram. The temperature-entropy diagram is beyond me just now.
https://en.wikipedia.org/wiki/Vapor-compression_refrigeration

 

[russ_watters]

A compressor compresses the gaseous refrigerant, causing it to heat up. Then it goes to a condenser where it is cooled and condenses at constant pressure. Then it goes through the throttling valve where the pressure drops and it cools. The diagram on that wiki page should make it clear what the four devices are that are associated with the processes in the p-v diagram: