How do I simulate a heat pipe in the Baseline case?
The proposed case has two split DX AHUs serving 22 & 15 zones respectively. A wraparound heat pipe is installed in each AHU to pre-cool RA & reheat SA with no energy use. The baseline case is composed of 37 type 4, PSZ-HPs per table G3.1.1A. I added a pressure drop correction to the Baseline case (0.65"wg estimated by manufacturer's software) to account for HP coils. LEED rejected this approach confusing the dehumidification function for heat recovery. Building is in climate zone 1a. Software is HAP ver4.6.
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
March 5, 2013 - 9:42 am
In our experience a heat pipe does not result in a coil placed in the air stream. So perhaps there is some confusion on the part of the reviewer about what it is you are doing.
With that said you don't model it in the baseline. If there is a fan power penalty you pay for using a heat pipe in the proposed, this penalty needs to be accounted for in the savings as well. Many energy recovery devices result in a fan power penalty and basically you cannot eliminate this with a baseline fan power adjustment.
The function of the coil, dehumidification, is the end use of recovered energy it sounds like to me but again maybe it is an issue of understanding what you are actually doing.
Kai Andrade
4 thumbs up
March 6, 2013 - 3:12 pm
As a follow-up question regarding the heat pipes: Since the wrap-around heat pipes in the proposed system function as “dehumidifiers,” would it make sense to model them in the Baseline system as a separate pre-cool coil and a separate electric reheat system located on either side of the main AHU coil?