Hello all,
Does anyone know of a method to model an air-source heat pump that uses the air handler exhaust stream rather than ambient air? The intent here would be to model an energy recovery that uses a heat pump (rather than a traditional HX) for energy recovery between the exhaust and supply streams. This is a lab building in climate zone 6 (central Vermont).
Any suggestions for workarounds or approximations are appreciated.
Thanks,
Ari
Ari Greenberg, LEED AP BD+C
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Ari,
You could model it as a water-to-air heat pump attached to a lake/well loop with a ground loop heat exchanger of type "Lake/Well". Then set the LOOP-TEMP-SCH to match the expected exhaust air temperatures, which I would think are predictable for a laboratory application. Zero out your pump energy but use the appropriate air-source EIR and HIR and consider changing the performance curves as an additional step. Be sure the heat pump coils are included in the fan energy on both the supply and exhaust sides. My first suggestion was going to be to model it as a heat recovery portion of another system, but your design probably has colder and/or hotter supply air temperature capability compared to the limitations of an air-to-air heat recovery system.
Regards,
Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
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I had a draft response to this but didn't send yet, so I'll jump in here...had some questions about whether the heat recovery coil will be the only coil in the supply AHU, or if there will also be hydronic coils so that the heat recovery is only a preheat/precool configuration?
David
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates