Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations The Obturator on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

ERV with added Refrigeration heat recovery

Status
Not open for further replies.

EnergyProfessional

Mechanical
Jan 20, 2010
1,279
I have that idea to enhance a regular ERV wheel with a refrigeration heat recovery (or rejection in summer). I drew up (attached) how that could look like and wonder if the best and brightest have come across that or have an opinion. Basic idea is:
1. Use ERV wheel to recover some energy and precondition OA
2. Add reversible heatpump to extract heat in EA and warm up OA (Winter operation) or do the opposite in summer (re-cool OA and reject heat to EA).

Potential advantages:
1. potentially better COP of heatpump in cooling since it rejects heat to the EA that is colder than OAT.
2. Potentially high COP to heat OA in winter since we extract heat from relatively warm EA.

Possible issues are:
1. added pressure drop due to condenser/evaporator coils. Obviously an energy simulation needs to determine if there is a net benefit.
2. potential freezing of EA coil if we extract too much heat (I'm in WI)
3. A small heatpump may have less overall efficiency than using a larger more efficient chiller for cooling OA.

Any opinions appreciated. Right now this is a very schematic concept without having done actual calculations for a real-world design.
 
 http://files.engineering.com/getfile.aspx?folder=c3d3d6ac-1b41-47c8-8b5d-34f677260d31&file=ERV_Refrigeration.PNG
Replies continue below

Recommended for you

So it looks like you are using the heat pump as an amplifier. If you can get a real gain it may be worth while.
I am adding a link to a similar project in Sweden without the heat wheel.
B.E.


You are judged not by what you know, but by what you can do.
 
 http://www.energy.kth.se/proj/Projects/ANNEX31/Workshop_Annex_31_Zurich_2008_Sweden_Jaime_Arias_2.pdf
So what do you see as the benefit to linking as you have? An ERW is useful for recovering energy from exhaust air where ventilation is required. It will not heat or cool by itself. A heat pump is is for actually heating or cooling to obtain a desired indoor temperature. There is no direct linkage between the ventilation air flow and the heating or cooling loads so I do not think your proposal is a great idea.
 
The heatpump would enhance the ERV wheel recovery, basically increasing effectiveness. Similar could be done by having 2 wheels in a row. so with one wheel 70% recovery, with 2 wheels 90%. Obviously the law of diminishing returns will bite us. The reversing heatpump would do something similar.

But now that I think about it more, 2 wheels probably would be more efficient without compressor, but similar pressure drop.

I wouldn't do a heatpump only, since the ERV will decrease EA humidity and recover humidity for OA. that also would decrease likelihood of freezing EA when the EA coil is in evaporator mode in winter.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor