A Recuperator

[hacknslash]

I was looking at the basic heat pump flow. What I'm understanding:
Vapor temperature returning to the compressor is at ~45 deg F after absorbing heat from the Ground Loop.
Compression raises the temp to about 135 deg F and the hydronic floor loop pulls the heat out and drops it to about 90 deg.
Vapor has probably condensed or is doing so as it cools waiting to run through the expansion valve where it dramatically drops in temperature to something like ~-35.
Then back to the Geothermal ground loop exchanger.

I think the whole idea behind geothermal is to get a better lift in the vapor temperature returning to the compressor than what you would see with air-source during the winter season. Is there a reason we can't do some of that lifting from transferring the heat from the condensing vapor in the condensor to the vapor returning to the compressor before all that heat is lost at the expansion valve? The values in the sketch are for indication only and not of actual performance.

My project would only require a heat pump in heating mode and no cooling.

Downsides I can think of:
There would be additional cost in heat exchangers.
Over-heat the compressor?

HacknSlash

[AC_Hacker]

Originally Posted by hacknslash

My project would only require a heat pump in heating mode and no cooling.

Would it be possible to re-draw your diagram using one color for the refrigerant flow, another color for the ground loop flow and a third color for the radiant floor loop flow?

It is confusing me, what your idea actually is.

I do know that in most situations, the de-super heat exchanger is meant to extract a comparatively small amount of system heat for the purpose of heating DHW. In your diagram, the radiant floor loop is the main heat load.

Otherwise, if you think it is a good idea, you should build it and let us know how it works out.

Nothing beats experimentation.

-AC_Hacker

[BradC]

Originally Posted by hacknslash

Over-heat the compressor?

^^^^^ This too.

If I get what you are trying to do, you want the vapor leaving the evaporator to absorb some of the heat from the condenser to lower the condensation temp.
The bit you are missing is the condensation process is where you draw the heat out for your hydronic heating, not the desuperheater. The heat available from the desuperheater is a very small percentage of the available heat from the system. So much so that you will find most people don't use a desuperheater and just dump that heat into the condenser.

If you want to lower the condensing temperature for less power consumption, use a bigger hx to bring the Td between your water and refrigerant down.

Have a look at a suction line heat exchanger (SLHX). In some cases good for cooling COP, but not really for heating.